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See: Joint permeability coefficient.

abrasion resistance

The property of a material to resist mechanical abrasive effects. Abrasion resistance is especially important for floor finishes.


This is the portion of the radiation, e.g. from the sun, that remains in the pane and heats up the glass. Coloured glasses absorb more than normal clear glass. Additional coatings can absorb more or less depending on the configuration. The absorption, transmission and reflection components must always add up to 100%.

acceptance test certificate

A person – not from the production department – appointed by the manufacturer and a person appointed by the ordering party, or a person nominated in the official acceptance documentation, confirm the results of tests on the basis of specific tests.

accommodation expenses

When it is necessary to stay in a hotel, guest-house, etc. overnight, the costs are reimbursed and the full amount can be deducted before payment of tax and social security contributions. If meals (breakfast, lunch or dinner) are consumed in the accommodation, the costs of these are deducted because otherwise the expenses allowance cannot be paid. A lump sum is paid in the case of an overnight stay in a private household.


Formal recognition of the competence of a facility to perform certain tests or testing methods. Accreditation is a term used in DIN and ISO standards, e.g. in connection with testing centres or with the official authorisation of certification to ISO 9001.


A colourless, combustible, readily volatile liquid. Used as a solvent in paints, acetylene and plastics.


A reactive, colourless, highly explosive gas. Used as a fuel gas in welding and as a raw material for plastics.

acid-etched glass

Generally known as obscured glass. The etched surface does reduce reflections but at the same time has the effect of making all colours appear matt and pale. Today, this type of glass is therefore used only rarely for picture frames.


The application of a caustic substance enables lettering or motifs to be “engraved” on the surface of the glass. The ensuing etched surfaces have a matt finish, but the strength of the glass is not adversely affected. Highly aggressive, toxic hydrofluoric acid is used for etching glass surfaces.

acoustic glass

Various methods can be used to improve the sound insulation properties of glazing. These methods include the use of special interlayers (PVB foil), laminated safety glass with an asymmetric configuration, a large cavity between the panes of insulating glass, possibly filled with a heavy gas, and glass with a lower strength. The construction of the elements supporting the glass also have an influence on the sound insulation. The characteristic variable for sound insulation is the weighted sound reduction index R.

acoustic laminated safety glass

This type of glass consists of two or more glass plies bonded together by acoustically effective polyvinyl butyral sheets (PVB-Si).

acoustic sheet/foil

This product improves the sound insulation properties of glazing owing to its chemical composition, which is tuned to certain frequency ranges.

across flats (A/F)

This is the distance between two parallel faces, which are mostly used as an interlocking connection for transferring a torque.

acrylate adhesive joint

This is a highly transparent jointing technique for glass. Only a very thin layer of adhesive is required which is cured by being exposed to UV light. One problem is the loss of strength in the adhesive joint due to climate influences. Currently, acrylate adhesive joints are used mostly for subordinate joints.

acrylic sheet

Often referred to as Perspex, a trade name, this is a light-fast and weather-resistant synthetic material that can be bent by applying heat and resembles glass because of its transparency. It is available in all colours, is hard and resists breakage, but is easily scratched and is not resistant to solvents or fire.

acrylic sheet

Usually referred to by trade names such as Perspex or Plexiglass, polymethyl methacrylate (PMMA) is a synthetic, thermoplastic material with an appearance similar to glass.

actual size

The dimension on a workpiece or component that was actually measured.

actual size

A dimension measured on the building site or in the factory. It may deviate from the planned dimension or still lie within the permissible tolerances.

additional work, extra

Work that was not originally included in the construction contract.


Adhesion is a bonded connection between different substances. The effect is based on the different powers of attraction between the individual molecules of the substances (molecular interaction).

adhesion failure

A failure mode in a loadbearing adhesive joint. Here, the layer of adhesive breaks away from one of the items being bonded together. Mostly caused by inadequate preparation of the mating faces. An adhesion failure in an adhesive joint is not permissible according to current legislation.


Generic term for a bonding substance used for construction and other purposes for thousands of years.

adhesive tape

Adhesive tape is the generic term for backing materials coated with an adhesive on one or both sides.

adhesive transfer tape

This is an adhesive tape without a backing, merely a thin film of adhesive that is protected on both sides by a waxed or siliconised protective paper prior to use.

aerated concrete

A relatively lightweight highly porous mineral building material based on lime, lime-cement or cement mortar which becomes porous during a foaming process and is always autoclaved.

aerial/elevating work platform

This is a machine with a platform that can be raised and lowered with a hydraulic or electromechanical mechanism. The platform is surrounded by a safety barrier with a means of access/egress. These machines use different raising/lowering mechanisms depending on the particular functions, e.g. moving arm, scissors lift, telescopic mast.

agate glass

This was originally a colloquial term for an opaque type of glass in which the mixing of harmonious colours resulted in an appearance similar to marble. In Austria this type of glass was produced up until the 1960s.

ageing of steel

Nitrogen is usually an undesirable tramp element in steels. In cold-formed sections, nitrogen segregates to dislocations in the crystal lattice where it causes unfavourable discontinuous yielding. One disadvantage of this is embrittlement of the steel, but this can be rectified by adding aluminium to form harmless aluminium nitrides.


The densest component and the best thermal insulation are useless when poor workmanship or poor detailing results in a construction that is not airtight. This not only increases the U-value (rising energy costs), but the leaks trigger a chain reaction: the resulting condensation leads to mould, which leads to damage to the building fabric over the long-term.

alabaster glass

This is a milk glass that has been ground to give it a matt finish.

alarm foil

This is a self-adhesive, multi-ply sheet into which a network of wires has been embedded. The foil is retrofitted to the glass and acts as a glass breakage detector complying with the highest risk class.

alarm glass

Upon being damaged or broken, this type of glass sends a signal to an intruder alarm system. To do this, a network of very thin wires, forming part of an electric circuit, is embedded in the interlayer of laminated glass.

alarm wire inlay

The network of fine wires embedded in the interlayer of laminated glass to form alarm glass. If the glass is damaged or broken, an intruder alarm is triggered.


Also known as aluminography, this is a type of offset printing process. However, in this process an aluminium plate is used instead of a lithographic stone because of the former’s lower weight.

alkali-lime glass

A type of glass with a high silicon dioxide content and smaller amounts of alkali oxides, calcium oxide, magnesium oxide and aluminium trioxide.

all-glass corner

This is formed when two glazing elements meet an angle in an SSGS façade. The omission of vertical framing members at this point results in a corner detail with maximum transparency. Building physics requirements place considerable demands on the design of an all-glass corner.

all-glass design

A glass construction in which the edges of the panes are partly or completely without frames.

all-glass façade

In this type of façade with its large expanse of glass the loadbearing construction (e.g. of steel, aluminium, timber, etc.) is replaced by loadbearing glass members. This results in a further dematerialisation of the façade, an even more transparent, even lighter appearance.

all-glass look

A façade design principle in which the loadbearing parts are positioned internally and are therefore invisible from the outside. This effect is mostly achieved by using SSG. In contrast to true all-glass assemblies, there is still a loadbearing structure of timber, steel or aluminium.

all-glass roof

In this type of roof with its large expanse of glass the loadbearing construction (e.g. of steel, aluminium, timber, etc.) is replaced by loadbearing glass members. This results in a further dematerialisation of the roof, an even more transparent, even lighter appearance, and allows a large amount of daylight to enter the interior.

all-Héroult process

At the end of the 19th century the American chemist Charles Martin Hall and the French scientist Paul Héroult both independently developed a method of electrolysis for producing aluminium. In this method aluminium is obtained from aluminium oxide by means of an electrolytic smelting process. Carl Josef Bayer improved the method.

alloying element

This is a substance that is added to a metal in order to modify its material properties.


A thermochemical treatment for coating a workpiece with aluminium.


A chemical element with the symbol Al and atomic number 13. The abbreviation is derived from alumen, the Latin word for alum. In the periodic table of the elements aluminium belongs to the boron group, which was previously called the group of earth metals. Aluminium is the third most common element and the most common metal in the earth’s crust.

aluminium alloy

Aluminium alloys are produced by alloying aluminium with other metals. In most cases the base material is Al99,5 (EN AW-1050A).

aluminium facing

A thin aluminium foil covering to an insulating material. This covering of aluminium makes the insulating material impermeable to vapour and is primarily used as a vapour barrier (the aluminium facing must be on the side adjacent to the room requiring installation).

aluminium section

Aluminium is a light metal and, owing to the thin layer of oxide that forms very quickly upon exposure to the air, has a matt, silvery grey appearance. It can be formed into complex sections by way of extrusion, and this is a great advantage when manufacturing hollow sections.

amorphous metal

Colloquially known as metallic glass or glassy metal, this is a metallic material with a disordered structure at the atomic level. The arrangement of the atoms is very unusual for metals and results in a unique combination of physical properties. Amorphous metals are normally harder, more corrosion-resistant and stronger than normal metals, but they generally lack the malleability so characteristic of metals.

ampere-hour (Ah)

The unit of electric charge. 1 Ah is the quantity of charge that flows through a conductor in 1 h with a constant electric current of 1 A.


A component that is used for fixing a screw or object to masonry or concrete. The commonest form is the anchor made from polyamide, a thermoplastic. The first industrially manufactured anchors appeared in 1910.


Anchors are used to fix façade elements to the building structure, for instance.

anchor plate

Steel elements are used to anchor beams, brackets or other steel components to concrete elements. These consist of steel plates to which anchor bolts are welded which are cast into the concrete to improve the transfer of tensile and shear forces. The welded anchor bolts create an interlocking structural connection.

angle grinder, disc grinder

A hand-held electric power tool fitted with a fast-rotating circular abrasive disc. The angle grinder gets its name from the fact that the drive is at 90° to the abrasive disc.


An optical phenomenon that occurs with toughened safety glass. The stress zones that build up within the glass during cooling can lead to double refraction of the light, which manifests itself in the form of visible coloured rings. This phenomenon is clearly evident during certain lighting conditions and is also seen in vehicle windows.


This term embraces all heat treatment methods that are based on raising the temperature of a workpiece to a certain level (annealing temperature), holding it at that temperature for a certain length of time (short or long) followed by slow cooling. We distinguish between full, partial, recovery, recrystallisation and diffusion annealing, also inter- and self-annealing.

annealing defect

If annealing temperatures are not maintained, the result is an unintentional modification of the microstructure. Exceeding the annealing temperature substantially for an extended period of time will result in material that is damaged, possibly completely ruined.

anodised aluminium

Aluminium parts whose surfaces have been given a protective layer (consisting mainly of aluminium oxide) in an electrochemical process, the purpose of which can be primarily protective, decorative or functional.


A surface treatment method for creating a protective layer of oxide on aluminium by way of anodic oxidation.

anodising quality of aluminium

Alloys in anodising quality are used in order to guarantee particular decorative effects or an especially uniform appearance. Such alloys are produced according to special methods.


Abbreviation for Analysis System, an FEM program suite for solving complex problems in structural mechanics. It is ideal for analysing glazing components. Comprehensive knowledge of FEM and component testing for calibrating the FEM models are essential.

anti-bandit glass

A transparent or translucent product made from several plies of glass, with or without plastic plies, that prevents or at least delays a violent attack (glazing resistant to manual attack, bullet- and blast-resistant glazing).

anti-crack reinforcement

Generally, steel reinforcement is provided to strengthen a concrete component, i.e. to provide concrete, which has a good compressive strength, with a tensile strength. Another application of this principle is the provision of supplementary reinforcement designed purely to prevent cracking of the concrete at exposed edges.

anti-drumming coating

Raindrops falling on sheet metal cause noise. The anti-drumming coating is applied to the underside of the sheet metal; it cuts down the noise because it reduces the ensuing vibrations that cause the noise. This coating therefore has a sound-insulating effect.

anti-reflection glass

Compared with conventional glass, this type of glass exhibits a lower degree of reflection. This property is achieved by applying a special coating. Anti-reflection glass is used to avoid disturbing reflective effects caused by lighting.

anti-reflection glass

The high transparency of this type of glass permits an excellent view of objects behind the glass. The observer is hardly distracted by light reflections nor by reflections of the surroundings, and can perceive colours clearly and with excellent contrast.

anti-reflective glass

The residual reflection from this type of glass is < 0.1% (with anti-reflection coating both sides). Potential applications: display areas, showcases, picture frames, shop windows.

antique glass

A coloured, hand-crafted type of blown glass. It is primarily used for artistic purposes.


The intersection of three or more roof surfaces at one point.

AR glass

This is the abbreviation for alkali-resistant glass.


This can be produced as a film, but is mostly produced in the form of fibres. Aramid fibres are golden yellow organic polyamides. They are characterised by their very high strength, high impact toughness, high elongation at failure, good vibration attenuation and their resistance to acids and alkalis.

arc welding

A method of welding that uses coated wire electrodes. After initiating the electric arc, the molten wire is transferred to the main material in droplet form. The coating forms a slag that prevents the ingress of air and can introduce additional alloying elements. This method is often used on building sites and for welding root runs.

arched roof

An arched roof consists of a curved roof surface only. The cross-section corresponds to a circular arc with an included angle < 180°. An arched roof is therefore flatter than a barrel-vault roof.


In the broadest sense, humankind’s involvement with the built environment. The methodical design and organisation of structures is the key purpose of architecture. There are many definitions of this term which assign various tasks, topics and meanings to architecture.


This is a colourless, extremely inert, monoatomic noble gas. Owing to its low thermal conductivity, one of its uses is as a thermally insulating filling between panes of insulating glass.

arrissed edge

The sharp arrisses of a cut glass edge are ground to reduce the risk of injury; the simplest form of edge working in the glass industry.


Removing the sharp burrs from cut edges. The surface of the cut edge is not worked.

as-built dimensions

The dimensions of an existing component or one provided by another trade.


In industrial production this is the planned fitting together of components and/or subassemblies to form larger manufactured items.

attestation of conformity

This is a document issued for a construction product by a certification body. The construction product must comply with the relevant technical codes of practice, National Technical Approval, National Test Certificate or Individual Approval and be subjected to internal and external quality assurance measures during its manufacture.


A systematic, independent examination of an actual situation and comparison with a target requirement. This is carried out to assess the effectiveness of a quality assurance system or parts thereof.

Auroraglas (aurora glass)

This is an old name for milk glass with a pink sheen.


A ?-phase solid solution of iron. The term austenite is also applied to other face-centred cubic structures. One example is the shape memory alloys. Austenite is the primary structural component in many stainless steels.


A ?-phase solid solution of iron. The term austenite is also applied to other face-centred cubic structures. One example is the shape memory alloys. Austenite is the primary structural component in many stainless steels.


A closable pressure vessel for the thermal treatment of materials at pressures above atmospheric pressure. In the glass industry autoclaves are used for producing panes of laminated glass. Subjected to high pressure and elevated temperatures, the interlayer bonds with the individual panes of glass to form laminated glass.


German abbreviation for tender, award of contract, billing (Ausschreibung, Vergabe, Abrechnung).

aventurine glass

This is a type of glass with shimmering inclusions. It is given this name because of its similarity with goldstone, a gemstone, which is also known by the name of aventurine glass and which shimmers because it contains traces of iron oxide.

average oxide layer thickness after anodising

The average value of a predefined number of measurements at various points on the visible surface of an individual anodised component.

axonometric projection

A three-dimensional representation of an object in which all parallel lines remain parallel and to scale (unlike a perspective, the lines of which converge).


The so-called b-factor (= shading coefficient) is often specified as well as the g-value (= total energy transmittance) for an insulating glass unit.

Bach plate formula

Simple equations for manual calculations, based on linear plate theory, for determining stresses and deflections in plates subjected to bending (i.e. out-of-plane) action effects.

backing cord

This is made from a material that does not adhere to silicone so that it can be used in a silicone joint to ensure that the silicone does not adhere to three sides.


On a mortise lock, the distance from the centre of the handle-bar to the front face of the gain. This dimension is specified in millimetres and is important for ordering and installing mortise locks.

ball impact test

In this test a ball machine fires two types of ball at the glazing at angles of 45° or 90°. In order to pass the test, the glazing may not be damaged.

ball-drop test

The ball-drop test is a standardised testing procedure for assigning laminated safety glass to the classes A1 to A3. The test involves allowing a steel ball to fall onto the glazing from various heights.


A safety barrier to prevent persons falling from a higher to a lower level. With either infill panels made from a suitable material (including glass) or individual, possibly ornamented, posts (balusters) made from wood or stone.

barrel finishing

A process in which metal parts are placed in a rotating drum to improve the quality of the surface and/or remove burrs.

barrel-vault roof

A roof form in which the roof surface corresponds to a half-cylinder. As the roof pitch at the middle is equal to zero, waterproofing problems can occur at this point.

barrier-free building

Barrier-free building is a designation for the design and construction of buildings and external areas so that they may be used without limitation by all people, i.e. also those who have some disability.

base glass

This is the glass produced directly from the glass melt. Only after cutting to size, drilling, edge working and other processing is the glass suitable for its intended purpose. Also known as primary glass.

bath side

This is the side of a piece of float glass that was in contact with the molten tin during its manufacture. A special UV lamp is used to determine which side is the bath side; the surface of the glass appears milky in ultraviolet light. Experimental studies have revealed poorer strength values in loadbearing adhesive joins when the bath side is used.

bath side

The designation for that side of float glass that was in contact with the bath of molten tin during production. This side is characterised by lower mechanical strength but better chemical resistance. It can be detected by shining UV light onto the glass, which causes the bath side to fluoresce slightly.

Bauhaus style

A style in architecture and design that is equivalent to that of the modern movement. In this style the individual parts of a building were separated according to their function, e.g. the façade was no longer a loadbearing component and therefore could be designed as required. Such a design feature is known today as a curtain wall in modern buildings with glass façades.


Currently the economic extraction of aluminium on an industrial scale is only possible with bauxite. Bauxite is mainly obtained from open-cast mines. The most important producing countries are Australia, China and Brazil. In contrast to other raw materials, there are still adequate deposits of bauxite available.

Bayer process

Named after the Austrian chemist Carl Josef Bayer, this method of obtaining aluminium involves mixing the crushed bauxite with aqueous sodium hydroxide solution, which is caused to react at a temperature of approx. 150 °C in order to separate it from impurities such as iron oxide and silicon oxide.


This is a plastic or steel cable contained in a membrane pocket which, because it is thicker than the membrane, can be secured against pull-out in a retaining member. Membrane structures can therefore be secured in position.

Beinglas (bone glass)

This is a type of milk glass in which bone ash is added to the glass melt to achieve the milky appearance of the glass.

Belleville washer

This is a conical metal ring that can be loaded in the axial direction. Static and dynamic loads are possible. The advantage of a Belleville washer is that large forces can be accommodated in a very small space, for example.


Bending involves the plastic deformation of a material by way of bending forces. This process is used in order to shape sheets, tubes, sections, wires and bars.

bending radius

When forming steel by way of bending, crimping or folding, a minimum radius inherent to the particular material must be adhered to so that the steel does not tear at the surface.

bending strength

A strength characteristic that is especially important for brittle materials (grey cast iron). The specimen is supported at both ends and loaded in the middle. The bending strength is not necessary for approval.

bending strength

The ability of a building component to accommodate and transfer bending moments. The bending strength of a steel beam depends on its second moment of area. Several beams can meet at a node and it may be necessary to transfer a moment across the node.

bent glass

Pane of glass bent to a predetermined shape with the aid of heat. Also known as curved glass.

Berliner roof

A special pitched roof form in which one roof surface is at a steeper angle than the other.

bevel both sides

One chamfer along each side of the glass.


A substance that that bonds together finely distributed solids (e.g. powders) or bonds them to a substrate. Binders are usually added in liquid form to the fillers to be bonded.

bird screen

A mesh or grating that prevents the entry of birds.

bitumen paint

Bitumen paint is used to protect building components (e.g. external basement walls) against moisture, metals (e.g. iron, steel) against corrosion or timber against weathering.

blast/explosion resistance

Glass types with a blast resistance classification protect persons and property against the effects of explosives. Such glass types are in the form of multi-ply laminated glass. Explosion-resistant glazing is allocated to classes D1 to D3 in the DIN standard, classes ER 1 to ER 4 according to EN 13541.

blastfurnace slag

A by-product that ensues during the production of crude steel in a blastfurnace. It consists of the impurities in the ore (gangue), coke ash and additives (burden).

blind façade

As a rule, a façade traces, or rather reveals, the segmentation or the cross-sectional form of the building behind it. However, a blind façade conceals the constructional nature of the building.


This is the background colouring to a large area of glass. The blotch colour is applied with a brush. Afterwards the surface is dabbed with a wad of material. The intention of this process is to create a matt, uniform distribution of the colour.

blower-door test

This test enables an assessment of the airtightness of a residential building. With the windows and external doors closed, a fan is used to force air into or out of the building with a 50 Pa pressure difference. The amount of air that escapes is measured. The result is the number of air changes per hour (n50).


The removal of excess carbon from molten or red-hot iron through the introduction of oxygen. Blowing with pure oxygen accelerates the steelmaking process and results in better steel grades.

blowpipe, blow tube

A hollow steel pipe 100–150 cm long with one wide end for picking up the glass melt and a mouthpiece at the other end into which the glass-maker blows.

blue glass

The blue colour is created by adding iron oxide and/or cobalt. Blue glass is relatively common; besides products for the building industry, it is used for decorative household objects.

body-tinted glass

This type of coloured glass is produced by adding small amounts of metal oxides to the melt. These reduce the light transmission and also the solar gains through the glass. The energy absorption of body-tinted glass is relatively high, which makes this type of glass vulnerable to thermal stresses. The panes are therefore usually toughened in order to prevent breakage caused by thermal stresses.

borosilicate glass

This is a type of glass that is resistant to chemicals and high temperatures. It is used for glass apparatus in laboratories and in chemical processes.


Hand-made, circular pane of glass with a diameter of 5–15 cm. It is used for leaded lights (bull’s eye or bullion).

boundary samples

A pair of different samples that specify the limits between which a colour or texture is acceptable in order to satisfy the approval criteria for erection. Boundary samples are used for anodised finishes, for example.

bowing and dishing

A climate-induced effect that affects insulating glass units. Due to pressure and/or temperature differences, the volume of gas in the cavity of an insulating glass units either expands or contracts. The individual panes of glass therefore move closer together or further apart. This aspect must be considered in the structural design of insulating glass units.


In a framework a brace is a diagonal member that increases the stiffness.


This is required to stiffen and stabilise a loadbearing structure. It must transfer the horizontal loads to the foundations or to other components. We distinguish between horizontal bracing in roofs or floor structures, and vertical bracing in walls.


Brass is an alloy of copper and zinc. It is somewhat harder than pure copper and in contrast to steel and aluminium alloys heat treatment does not render it susceptible to age-hardening.

brass light

This is essentially the same as a leaded light, except that brass-covered lead cames are used instead of pure lead cames. This improves the appearance compared to standard leaded lights.


Building Research Establishment Environmental Assessment Method. A British evaluation system for certifying the total performance of a building relevant to the environment and the guidelines for design and management processes. BREEAM is the most common certification system on the international market and includes local adaptations for the Gulf region or the rest of Europe, for instance.

bridge packer

These are special raised setting blocks with a ventilation channel underneath which guarantees vapour pressure equalisation around the periphery of the glass.

bright steel

This is produced from hot-rolled, occasionally forged, steel through descaling and subsequent cold-forming. It has a shiny, smooth surface and much better dimensional accuracy than hot-formed steel products.

Brinell hardness

A hardness testing method developed in 1900 by the Swedish engineer Johan August Brinell. It is used for soft to medium-hard metals, e.g. unalloyed engineering steels or aluminium alloys, also timber and materials with an irregular microstructure, e.g. cast iron. The test involves pressing a hard steel ball into the surface of the material to be tested with a defined testing force.

brittle failure

A typical failure mode for glass. Local stress peaks lead to abrupt failure of the component without warning, e.g. in the case of severe deformations.


Bronze is an alloy of copper that usually contains tin, but sometimes other metals as well. It was one of the earliest alloys produced by mankind. Today, sieve meshes, bearing bushes, fittings and the screws of ships and boats are made from bronze.

bronze-tinted glass

The bronze colour is produced by adding selenium. Bronze-tinted glass is frequently used for attenuating brightness or in interior architecture for decorative purposes.


A computer program for viewing Internet pages or other documents and data.


German abbreviation for floor-mounted door closer (Bodentürschließer).


A loss of stability, right up to complete failure, of straight or minimally curved linear members or beams due to the effect of compressive forces, whose line of action coincides with the axis of the member, and/or bending moments. The slenderness of a component is critical for the risk of buckling.

building architecture

The discipline that deals with the architecture of buildings that rise above ground level.

building authority

In many countries a building authority is responsible for approving and monitoring certain construction projects that require approval/permission. The prime task is inspecting the execution of the construction approved according to an approval issued with corresponding stipulations.

building component

In architecture or construction the designation for a discrete part of a structure or building.

building envelope

This is the term for the outer “hull” of a building: the façades plus the roof. There are sometimes no distinct divisions, making it difficult to tell where a façade ends and the roof begins.

building physics

Building physics is a branch of physics that is concerned with the physical properties of building materials, components and buildings themselves. The building physics properties of materials and components are laid down in standards and regulations. Building physics can be subdivided into four main areas: fire protection, thermal insulation, moisture control and sound insulation.

bullet resistance

In a bullet-resistance test, appropriate weapons are used to fire suitable projectiles at the glass in order to establish to what extent the glass is penetrated. The test also involves checking whether splinters of glass are ejected from the rear surface of the glass even if a projectile does not penetrate the glass. Swiss standard SIA 331.511 applies, which is equivalent to EN 1063. There are five classes, C1 to C5.

bullet-resistant glass

Laminated safety glass that can withstand impacts, projectiles and blasts and is therefore suitable for protecting persons and property.


A mixture of iron ore, fluxes and possibly scrap that is fed through the throat into the blastfurnace.


Burnishing is used to create a protective layer on surfaces containing iron in order to reduce corrosion. Immersing the workpieces in acidic or alkaline solutions or salt baths causes the formation of jet black mixed iron oxide layers. Burnishing is not a coating treatment.

butt hinge

A door hinge that is mounted in the rebate so that from the outside only a narrow cylinder is visible when the door is closed.

butt joint

A butt joint is formed when two panes of glass are bonded together either in line or at an angle. The edge of one pane is therefore butted up against the edge or surface of the other.

butterfly test

A quality test for structural glazing silicone. This test has to be carried out upon starting up mixing equipment and after mixing two-part compounds. The purpose of this test is to check the quality of the mixing of the silicone.

butyl seal

The hermetic edge seal to an insulating glass unit.

cable bracket

A fitting that is attached to a wire rope with a fastener or held in place by tension. A rocker mechanism in the bracket enables vibrations in the wire rope to be accommodated.

cable net façade

In this type of construction for a glass façade the conventional loadbearing construction (e.g. of steel or aluminium) is replaced by a delicate net of wire ropes which results visually in an essentially dematerialised structure. The panes of glass are fixed to the wire ropes with special fittings. The great appeal of this type of façade is its lightness and transparency.

cable-supported construction

This type of construction can be used to construct delicate-looking roofs, façades and bridges. Extraordinary technical and aesthetic achievements are possible in this way.


Computer-aided design is the term used to describe the production of design documents with the help of suitable software.


Computer-aided engineering is the generic term for all computer-assisted working processes. Those processes include: CAD, FEM, CAM, CAQ. The networking of individual parts of a process increases the effectiveness of a project and helps to reduce costs. Computers are being required more and more in order to cope with the complexity of large projects.

calcium oxide

Also known as quicklime, this is a white powder that reacts with water and in doing so releases a large amount of heat. This reaction with water leads to the formation of calcium hydroxide (slaked lime). Calcium oxide is a fundamental constituent in the production of glass.


The comparison of measured values with those of a reference or normal condition. The work involves assessing the deviation between two values or whether this deviation lies within certain limits.


Computer-aided manufacturing is the term used to describe the control of production plants plus the associated transport and storage systems by means of suitable software.

cameo glass

This is a multi-layer coloured glass made from flashed glass. A layer of white glass is added to a layer of coloured glass. Afterwards, decoration is introduced with a copper engraving wheel. This decoration remains as a raised relief.


This special shaft controls the inlet and outlet valves of an engine and is driven by the engine itself via a toothed belt or chain. The camshaft is designed to open the valves at the right times, with the exact stroke and in a precisely predetermined sequence, and allow them to be closed by the valve springs.


A cantilever is an element that projects from a building and is therefore unsupported at its outer end, e.g. oriels, balconies, even whole storeys, which may be supported over part of their cantilevering length by corbels or cantilevering beams.


A form of construction supported at one end only.


A cantilevering component, e.g. beam, rafter, purlin, suspended floor slab, spans without support from walls or columns at some point.


A sheet metal covering to the top surface of a parapet, with a fall to the inside so that no water remains on the parapet.


When carbon in the form of an anion bonds with a metal in the form of a cation, the resulting reaction product is the chemical compound carbide.


This is a chemical element. It occurs in nature both in pure form and in chemical compounds. The amount of carbon added to iron determines whether the resulting steel is hard, brittle or malleable.

carbon (C)

The hardness and strength of a material are affected by the amount of carbon it contains. However, too much carbon in a material reduces its cold workability considerably.

carbon monoxide

A colourless, odourless, tasteless toxic gas. It is formed by the incomplete oxidisation of carbonaceous substances. This takes place, for example, during the combustion of such substances when there is not enough oxygen available or the incineration takes place at high temperatures.

carbon steel

The incorrect designation for an unalloyed steel, i.e. a steel without any further alloying constituents.


In construction the elements of a structure, including the roof, that give it its overall contours, but excluding the interior fitting-out.

cast glass

An erroneous term for rolled glass.

cast iron

Iron in cast form contains 2–4% carbon which is essentially in the form of graphite, or rather temper carbon, and is not subjected to any further forming work.

cast-in channel

This is a steel C-section that is cast into the concrete so that T-head bolts for attaching other items, e.g. ventilation ducts, pipes, etc., can be fixed at any position along its length at a later date.

cast-in part

This is a component that is fitted between the reinforcing bars of a reinforced concrete element so that it is cast into the concrete. The cast-in part is designed in such a way that the action effects to which it is subjected can be optimally transferred to the concrete.

cast-in part

A component that is cast into concrete, e.g. for the fixing of brackets or other similar components.

castellated beam

This is fabricated from a rolled I-section that is torch-cut into two parts along a trapezoidal line. The two halves are then welded together. The resulting beam section can carry considerably heavier loads because of the increased distance between the tension and compression zones.


Filling a pattern with molten glass.

casting resin

A synthetic resin that is worked in the liquid state to form the final product and solidifies to form the product or part thereof. Casting resin is used to bond panes of glass together. Better sound insulation values can be achieved with casting resin. In Germany the use of casting resin for overhead glazing is, however, only possible with an Individual Approval.

cat-slide roof

A pitched roof form in which one roof surface or part thereof projects beyond the eaves.

cathedral glass

This is a type of rolled translucent glass with an irregular, small or large hammer tecture. Also available in colours.

CE marking

A manufacturer who marks a product with the CE symbol confirms that it complies with the relevant European safety directives. The CE marking does not necessarily mean that the product has been inspected by independent bodies for compliance with directives and is also not necessarily a mark of quality.

cellular glass (CG)

Foam thermal insulation material with a closed cellular structure made from silicate glass. The basic properties such as expansion and chemical resistance correspond to those of silicate glass. Cellular glass is impermeable to water vapour diffusion.

cellular rubber

A porous, foam-like elastomer that is used as a seal, a soft backing pad, and for insulating, isolating, noise-attenuating, anti-drumming and many other purposes.


A hydraulic binder used in mortars and concretes.

cemented carbides

These are sintered carbides. They are characterised by their extreme hardness, abrasion resistance and especially their stability at high temperatures. Cemented carbides are used for the tips of tools and parts used in metal-cutting processes, non-cutting forming processes and where frictional abrasion is an issue.


A compound of iron and carbon, with the chemical formula Fe3C (an iron carbide), that occurs as a metastable state in steel and white cast iron.


Abbreviation for European Committee for Standardisation, a European standardisation body similar to DIN and ISO.

centrifugal casting

In centrifugal casting the molten metal is cast in a rotating tubular mould. The centrifugal force causes a compaction of the microstructure, which therefore increases the strength. Centrifugal casting is used to produce cylindrical and conical workpieces, e.g. pipes.

ceramic bead blasting

This is a method for smoothing and also finishing surfaces which achieves a consistent, uniform satin finish. The use of ceramic beads results in a much lower breakage rate than is the case with glass beads. This reduces the roughness which in turn decreases the chance of dust and dirt adhering to the finished surface.

ceramic certification stamp

This stamp is used to identify a type of glass. It is obligatory for thermally toughened glasses and is applied during the toughening process.

ceramic screen printing

This printing technique enables areas of colour and pictures to be printed. Slides or photographs can be digitalised for the motifs, which are exposed on a mesh screen and subsequently fired at a temperature of 700 °C. Ceramic screen printing is light-fast, solvent-resistant and abrasion-resistant. It also remains stable at temperatures of up to 200 °C.

certificate of compliance

In this document the manufacturer declares that the product supplied complies with the order. It does not contain any details about test results.

certificate of origin (CO or COO)

A document used in international trade for verifying the exact place where goods originated. This document enables import quotas or customs duties to be applied as required because such quotas and duties depend on the country of origin.

Charpy impact test, Charpy V-notch test

This test carried out according to DIN EN 10045 determines the brittle failure behaviour of materials depending on the temperature. For welded connections in particular, selecting a suitable notch position enables both the quality of the weld and also the heat affected zone (HAZ) to be investigated separately.

Chauvel glass

A type of sheet glass with a parallel wire inlay and flat surface achieved by working after rolling so that the view through and reflections are not distorted in any way.

chemical decolourisation

The aim of this process is to convert colouring oxides into other oxides so that the (dis)colouration is as light as possible. For example, in the melt, an iron oxide with a strong colorific effect is converted into an iron oxide with a reduced colorific effect by introducing oxygen. Another method of decolourising is physical decolourisation.

chemical resistance

Glass is very resistant to the majority of chemicals. This resistance increases with the SiO2 content and can be influenced by the composition of the glass. Hydrofluoric acid (HF) causes visible damage directly and reacts with the SiO2 to form gaseous silicon tetrafluoride which destroys the structure of the glass.

chemical toughening

This amounts to hardening and is used on thin panes of glass 2–3 mm thick. The glass is immersed in a potassium nitrate melt, which results in an exchange of ions. This causes a compressive stress to be generated at the surfaces, which improves the strength. The compressive stress is greater than that generated by thermal toughening.

cherry picker

A self-propelled work platform with an articulated telescopic boom. This is a flexible type of working platform that is easily operated and suitable for many different applications. Battery-driven, electric and diesel versions are available for internal and external deployment.


This is a flaw that often occurs on a cut glass edge. Damage to the surface, e.g. caused by a stone, often displays a similar form.


A surface treatment in which an electrogalvanic process is used to coat workpieces with a protective layer containing chromium. The resulting chromate layers are classed as passive coatings, i.e. they are inorganic non-metallic protective layers.

chromium (Cr)

This element increases the tensile strength through the formation of a solid solution, and reduces the critical cooling rate. It increases the depth of hardness and the resistance to scaling. Above a concentration of 13 % in ferritic and austenitic steels, chromium also helps to prevent corrosion through the formation of a resistant layer of chromium oxide.

chromium oxide

This is a chemical compound of chromium and oxygen. Chromium oxide is mixed with the glass during production, often in conjunction with iron oxide, to give the glass a green colouring.

chromium plating

Electroplating method for improving the surfaces of metals and plastics. The thin layer of chromium provides a shiny coating that protects against corrosion. Chromium plating requires a very high energy input and highly toxic electrolytic baths. Expensive pretreatment of workpieces is essential for a good result.

Chubb lock

A lock invented by Jeremiah Chubb. The stepped bit lifts several levers in such a way that the bolt can be moved. This type of lock was common in Germany until well into the 1960s.

clamp fixing

U-shaped clamp fixings to fit around the edge of the pane of glass. No holes need to be drilled through the glass. An elastomeric pad prevents contact between the glass and the metal fixing. The glazing edge cover must be guaranteed, even when loads are applied.

clamped membrane

In a clamped membrane design the loadbearing connection between the flexible membrane and rigid components is by way of clamping the beading at the edge of the membrane in a special rail, which is usually made from extruded aluminium.


The client is the person who prepares and carries out building works or has them prepared and carried out on his behalf.


Panes of glass with an acute angle, e.g. triangular panes, must be “clipped”, i.e. trimmed off, cut back, because otherwise there is a great risk of the corner being chipped and the whole pane spoiled.


Coatings are as different and versatile as the materials to which they are applied, e.g. a façade construction. Common to all coatings is the fact that they protect and affect the material to which they are applied.

cobalt (Co)

This element improves the resistance to tempering, also the heat resistance.

cobalt oxide

This is a chemical compound of cobalt and oxygen. Cobalt oxide is mixed with the glass during production to give it an intensive blue colour, but can also be used to remove colour.

coefficient of thermal expansion

Materials expand differently when exposed to high temperatures and this coefficient must be considered during the planning.


The inner strength of a substance that ensues through the interaction of forces of attraction between its individual components. In physics and chemistry we speak of the interaction between atoms or molecules, in soil mechanics the interaction between soil particles.

cohesion failure

A failure mode in a loadbearing adhesive joint. Here, the failure occurs within the layer of adhesive or within one of the items being bonded together. According to current approval procedures, a cohesion failure is the only type of failure permitted; adhesion failures are not permissible.


Steel strip, tube or wire wound up into a roll.

coil coating

This is a method for coating continuous strips of thin steel or aluminium on one or both sides. It represents an alternative to traditional coating techniques.


An apparatus for winding/unwinding strip, sheet or wire products into/from coils.

Colburn process

In this process the glass is drawn vertically out of the melt without the need for a die. The ribbon of glass is bent over a roller at a height of approx. 60?70 cm and then passes into a horizontal annealing lehr. Irving Wightman Colburn registered his invention in the USA in 1905


The abbreviated form of colloidal concrete, a method of concreting in which in contrast to conventional concreting the aggregates (e.g. gravel, ballast) are first placed in the formwork and then the ensuing voids injected or filled with grout (colloidal grout). The particular advantage of this concrete is its low shrinkage.

cold façade

This is a suspended, curtain wall-type external wall construction with a ventilation cavity. In contrast to a warm façade, all parts of the spandrel panel elements are exposed to the exterior climate. All parts of the construction can be designed without a thermal break because there is no connection to the warmer interior of the building.

cold-rolled strip

A flat metal product produced in widths of up to 650 mm and thicknesses of 0.1–6.0 mm. It is available in all steel grades and with any type of surface finish.

cold-rolled strip steel

Flat products manufactured by cold-forming from hot-rolled strip steel. The cold rolling reduces the cross-section by at least 25%, and after passing through the finishing roll, or rather after pickling or continuous annealing, the strip is wound up into a coil.

cold-warm façade

The cold and warm areas alternate in this type of façade. The components of the façade are mounted on loadbearing external walls built of masonry or concrete. In the warm zones fixed and moving window elements close off the openings in the structure by means of sections with thermal breaks and insulating glass. In the cold zones the surfaces of the structure are provided with a weatherproof glass skin.

colour rendering index

The colour rendering properties of a particular type of glazing are specified by the general colour rendering index Ra. The Ra scale extends up to 100. The optimum Ra value achievable with glazing is 99.

coloured anodising of aluminium

This is anodised aluminium that is coloured either during or after the anodising process.

coloured glass

We distinguish between body-tinted glasses and those with a coloured enamel or other coating.


We essentially distinguish between three types of products used for colouring glass: solvent dyes, temper colours and sulphur dyes.


A (mostly) vertical component that carries and transfers loads primarily in the direction of its longitudinal axis. DIN 1045-1, the standard for plain, reinforced and prestressed concrete, defines a column as a linear compressive member.

combination value

In order to be able to reflect the simultaneous application of several loads in a better way, the action affects are multiplied by factors (? 1). Combination values form part of the semi-probabilistic partial safety factor concept.

commencement of works

Construction works on site may only begin after the issue of the legally binding building permission to the client and after the building authority responsible has been notified in writing of the commencement of works.


The compatibility of laminated safety glass must be considered with respect to loadbearing adhesive joints, the hermetic edge seals of insulating glass and polyvinyl butyral (PVB) sheets. Incompatibility with adjacent materials can alter the material in such a way that it no longer fulfils its intended function. The result is failure of the adhesive joint, leaking edge seals or delamination phenomena in laminated safety glass products.


Many different materials and surface finishes come into contact in buildings and structures. It is therefore especially important to check that all materials in contact with one another are compatible or that they are separated by intermediate layers. seele checks the compatibility of the materials used for every construction project.


This is the amount, expressed as a percentage, by which a membrane bay has to be cut undersize because of its stretching behaviour so that the bay achieves the desired geometry after prestressing. Owing to the method of manufacture, compensation is usually greater in the weft direction than in the warp direction.

composite action

A term from structural analysis. In glass construction this is the possibility of transferring shear stresses across the interlayer or casting resin. However, according to German regulations any beneficial effects of composite action may not be taken into account for laminated safety glass.

composite construction

A composite construction results when the load-carrying capacity of an element is realised by the combination of different materials. Glass is ideal as a material for composite construction because it can accommodate enormous compressive forces, but quickly fails when subjected to tension. In such cases, steel can accommodate the tensile forces.

composite construction

In this form of construction at least two different, separate materials are joined together by means of fasteners in an interlocking way in order to combine the advantages of both materials. Generally, composite construction refers to the combination of concrete and steel. However, other combinations, e.g. with timber, are possible.

composite material

Such a material is made up of two or more materials that unite the positive properties of the individual materials in a new material. Often simply referred to as a composite.

compound angle cut

A timber or metal section cut at two angles simultaneously (sometimes referred to as jack rafter cut).

compression glazing

A method of glazing in which the sealing to the rebate for the pane of glass is achieved by a preformed gasket which is compressed in some way (screws, springs, cams, wedges, serrations) by a metal glazing bead.

compressive strength

The compressive strength of a material is its resistance to the effects of any compressive forces acting on it. An element will fail if the compressive stress induced is greater than its compressive strength. Most materials exhibit different compressive and tensile strengths, e.g. stone, steel.

compressive strength of float glass

Float glass has a compressive strength of 700–900 N/mm².


In optics a concave surface is a form that curves inwards.


This is a mix of cement, aggregates (sand, gravel, chippings) and water. When the cement reacts with the water (hydration), the aggregate is interlocked by the ensuing crystal lattice and can therefore transfer high compressive forces. Owing to its much lower tensile strength, concrete is often strengthened with steel reinforcement (reinforced concrete).


Water vapour condensing out of the air that collects on a cool surface. On external components with poor thermal insulation (e.g. single glazing) there is a risk of the temperature dropping below the dew point when the outside temperature is low, which leads to condensation collecting on the internal surfaces.


Condensation collects, e.g. on single or double glazing during the cold months of the year, when the surface of the glass is colder than the adjacent layer of air. Owing to the fact that the hermetic edge seal to the pane is less efficient in thermal terms, condensation always starts to collect at the lower edge of the pane.

condensed matter

In science this is the matter in a bonded state as opposed to a gaseous state.

conical roof

This is similar to a pavilion roof but circular on plan.


This is the colloquial term for a connecting rod, the connection between a rotating crankshaft and a component with a linear motion, e.g. a piston.

construction science

Knowledge of the theory and practice of the construction of buildings and structures.

continuous beam

A loadbearing member that is rigid over several spans. If floor beams or purlins are designed as continuous members, the span moments are reduced due to the relieving effect of the support moments. Deflections are also much smaller. Continuous beams are statically indeterminate systems and therefore require a more complicated analysis.

convection in the cavity

The air circulating in the cavity of an insulating glass unit transports heat quickly from one pane to the other, which leads to a worsening of the U-value.


A cylindrical vessel with a refractory lining which tapers towards the top.

copper oxide

Copper forms bivalent and trivalent copper oxide in the presence of oxygen. Copper oxide is mixed with the glass during production to give it a blue or red colouring, depending on the valency.


A steel alloy with a high weathering resistance because a protective layer of iron oxide (rust) prevents further corrosion media from attacking the steel. COR-TEN is suitable for welding and forging, and owing to its characteristic rusty brown appearance, is employed by architects for its aesthetics.

corner connector

For joining together mitred corners. They can be nailed, screwed or glued.

corner plate

The perimeter cable of a membrane roof is fixed to the corner plate via a special fitting at the end of the cable. The corner plate is in turn connected to another component, usually of steel, to which it transfers the load.


The topmost moulding on a building.

corridor façade

A double-leaf façade in which the cavity is divided horizontally and ventilated per storey. The cavity is normally accessible, hence the name.


This is the unwanted, undesirable reaction of a material with substances in its surroundings. It occurs most of all with metals.

corrosion protection

Corrosion protection prevents a material being damaged by external influences. Paints and coatings are typical corrosion protection systems. However, there are also materials that require no protection against corrosion, e.g. stainless steels.

corrosive medium

A substance that has a corrosive effect on a material. Corrosive media include, for example, indoor air, outdoor air with or without industrial pollutants, water, soils and chemicals.

corrugated sheet metal

This is sheet metal with a wave-type cross-section. The sheet metal is usually comparatively thin and so it is the wave-like form that gives this material its high rigidity and load-carrying capacity. Corrugated sheet metal can be flattened and also bent to form a cylinder.


A counternut is an additional nut used in a bolted connection which is tightened against the main nut. The nuts deform and this increases the friction force in the flanks of the thread which prevents the nuts from being turned, i.e. loosening. Also known as a lock or check nut.

countersunk fixing

A point fixing that holds glazing in place by means of a component fitted into a hole drilled through the glass. The hole for a countersunk fixing must be partly cylindrical, partly conical.

CR profiles

Chloroprene rubber profiles for sealing windows and ideal for using as the frame and overlap seals, but also for gasket glazing.

cranberry glass

This is a general term for delicate pink to dark red glasses that are coloured by dissolving gold chloride in the glass melt. Also known as gold ruby glass, it has been ousted from the market by the less expensive, more yellowish selenium ruby glass and the often somewhat brownish copper ruby glass.


A crane is a machine for lifting and transporting building materials and components on the building site.


This special shaft is a component in a reciprocating or piston engine which, with the help of conrods, converts the movement of one or more pistons into a rotation. Together, the components necessary for converting the movement are known as a crank drive.

crawler-mounted aerial work platform

These robust, compact elevating platforms mounted on long, wide, rubber crawler tracks are ideal for applications on unstable surfaces, e.g. on building sites. They have their own drive unit, are extremely manoeuvrable and can therefore adapt well to the given ground conditions.


The slow deformation of a material subject to a constant load. Polyvinyl butyral (PVB) sheets are very susceptible to creep at high temperatures, which can reduce the residual loadbearing capacity of a pane of glass. SentryGlas® (SG) has much better properties in this respect.

Cremona diagram

This is a method for the graphic determination of the forces in the members of statically determinate frameworks. It was invented by the Italian mathematician and structural engineer Antonio Luigi Cremona.

crew/bolt retainer

Such a fitting merely prevents a fastener from becoming completely undone. Some loosening may be possible and that may involve a loss of the preload required for the design. Methods include counternuts, special nuts and washers, wires, plates, etc.

crosshead screw

The screwdriver recess in the head of this type of screw is in the form of a cross. Crosshead screws have almost completely replaced slotted screws in industrial production.

crown glass

A large manually blown globe of glass is rotated to form a circular disc which, after annealing is cut into panes. This glass is characterised by its concentric structure. The thicker section, or boss, left in the centre where the pontil rod was attached is the bull’s eye or bullion sometimes seen in old windows and imitated today. This form of glass production is no longer common.

crude steel

A fluid or solid primary product used for steel castings or in the form of ingots.


Abbreviation for Common Understanding of Assessment Procedure, an approval procedure for obtaining a European Technical Approval when there is no guideline (ETAG) available. The object of the approval is submitted to all the European technical approval bodies in order that they can give their opinions. This process can be very lengthy.


This is scrap glass that is recycled by mixing it, in the form of fragments, into the glass melt. Hollow or pressed types of glass should not be used as cullet.

Culmann’s method

A graphical method for solving problems in structural analysis. In order to be able to use this method, four forces with known directions are required and the magnitude of at least one of these forces must be known.

currency safeguard

A precautionary measure against risks resulting from the fact that a business partner is located in a different currency zone or uses a different currency.

cut edge

An unworked straight edge.


This is the part of a biological cell that is enclosed within the cell membrane.

Dalle de Verre

This is a body-tinted, light-permeable glass. Mostly supplied in the form of small slabs with an irregular surface.

Danziger glass

A special type of true antique glass. It has a very streaky surface with incisions, scratches and air bubbles. (Danzig is the German name for the Polish city of Gda?sk.)


Sound pressure weighted according to frequency in line with weighting curve A (DIN 45633). This curve takes into account the fact that the perceived loudness depends on the frequency (pitch). Also used as a unit of measurement for sound level. Corresponds roughly to the phon value at 1000 Hz.


Delivery duty paid: the seller is responsible for making the goods available to the buyer at a named destination and also responsible for all import customs formalities and duty and for final delivery of the goods to the buyer at the destination.


Delivery duty unpaid: the seller is responsible for making the goods available to the buyer at a named destination but not cleared for import. The seller is also responsible for all costs involved in delivering the goods to the destination. The seller’s risk does not end until the goods reach the destination.

dead load

The effective weight acting on a building component due to the total mass of the building materials and any stored materials.


As even tiny impurities in the raw materials can cause undesirable discolouration of the glass, the glass can be either chemically or physically decolourised.

decorative hardware

Ornamental fittings made up of straps, strips and rosettes that look like metal fittings held in place by rivets. These are decorative items without any technical function.

deflection limit

A deflection limit guarantees the serviceability of a design. Loads acting on toughened glasses can cause very large deformations. These must be kept within reasonable limits. The deflection limit can also apply to the supporting construction in order to guarantee the durability of insulating glass, for instance.


The process of removing the glass from its frame or supporting construction, a process that can be made easier, for example, by using glazing beads that are merely clipped in place.

degree of reflection

This specifies the percentage of visible light that is reflected from the surface of a pane of glass.


The layer-by-layer breakdown in a laminated material composite, e.g. a PVB sheet becoming detached from the surface of the glass. In glass construction the main reason for delamination is incompatibility between the plasticisers in silicones and PVB sheets.

dense concrete

Concrete with a density of 2.8–4.5 kg/dm³. Dense concrete is a mix of cement, aggregates and water.


This is the mass of a body related to its volume.


The ratio of the mass of a body to its volume. This is specified, for example, in g/cm3 or kg/l. Considered as a descriptive term, it describes whether the body, for its weight, is as “light as a feather” or as “heavy as lead”.


The removal of mill scale (caused by rolling or annealing). Descaling can be carried out by mechanical, chemical or electrochemical means.

destructive test

A test that generally results in the destruction of the material. It is used to identify internal or external irregularities or to estimate mechanical or metallurgical properties by means of mechanical effects.

Deutsches Institut für Normung (DIN)

This is the national standardisation organisation for Germany and represents German interests in European and international standardisation work. The task of the organisation is to define standardisation efficiently, and to prepare standards as a service for industry, state and society.

dew point

The temperature at which water vapour in the air condenses on a building component. In its roof and façade designs, seele makes sure that the dew point lies in a layer that is ventilated by the outside air so that any condensation that might form dries out again and does not cause any damage.

dew point chart

The external temperature at which condensation forms on the inside face of a window pane can be determined from this diagram depending on the relative humidity of the air and the U-value of the glazing.

dew point temperature

The temperature at which water vapour changes to liquid form in the form of fine droplets. The higher the humidity of the air, the higher is the dew point temperature.


Deutsche Gesellschaft für nachhaltiges Bauen (German Sustainable Building Council). The task of the DGNB is to determine and promote measures and solutions for designing, constructing and using buildings in order to realise the aims of sustainable building. The DGNB awards a certificate for buildings certified as sustainable.


Deutsche Gesellschaft für Qualität e.V. (German Society for Quality)


Double glazing unit, i.e. insulating glass.


Deutsches Institut für Bautechnik (German Institute of Building Technology). The DIBt is the only German approval body for construction products and forms of construction.

dichroic glass

A glass product with a coating of thin layers of metal oxides with different light refraction characteristics which form a system of interference layers so that light is split into its spectral colours. These coloured effects vary depending on the sunlight, viewing angle and background.

diesel scissor lift

This type of elevating platform is characterised by its good operation on different terrains, especially loose, unstable surfaces. All-wheel drive and the option of using outriggers to compensate for uneven ground make such lifts ideal for outdoor uses.


This is a special epicyclic or planetary gear, e.g. between the driven wheels of a vehicle. As the wheels on one axle travel different distances when traversing a curve, this difference may not become excessive in the case of rigidly coupled wheels.


The process of mixing together two substances with different chemical properties. In construction this term is used for an exchange process, especially for water vapour being exchanged between the air and the surface of a wall or a porous material.

DIN 18008

German standard currently in preparation that will cover the use of glass in building. It is intended to bring together and replace the existing regulations (TRLV, TRAV, TRPV) and add further new ones. But the standardisation work cannot keep pace with the rapid developments in glass design, which is why Individual Approvals are necessary again and again.

DIN 276

This German standard regulates the estimation of costs in construction, especially for building and civil engineering works. It defines the procedure for estimating costs and is divided into five stages: cost framework, cost estimate, cost calculation, cost quotation and cost determination. The corresponding standard in Austria is ÖNORM B 1801-1.

direct reduced iron

Also known as sponge iron. The reduction of iron ore in the solid state produces a sponge-like product with a large pore volume which contains small amounts of oxygen and slag. Direct reduced iron is further processed in an electric arc furnace or can be used in powder metallurgy.


A glass defect that results from impurities in the raw materials. Even the tiniest impurities can lead to undesirable colour casts. The glass can be decolourised in order to overcome discolouration. We distinguish here between chemical and physical decolourisation.

distance between flanges

This is the clear internal distance between the flanges of a steel I-section. German HEA, HEB and HEM sections with the same section number have the same distance between flanges, which results in advantages for design and construction.


A dome is a hemispherical or similarly shaped roof over a building or part thereof. The glazed dome on top of Germany’s parliament building in Berlin, the “Reichstag”, is one prominent example.


A door is boundary component between rooms or between interior and exterior which still permits the passage of persons or goods. Doors can be locked to prevent the entry of unauthorised persons. Doors also perform other functions such as thermal and sound insulation and can also be designed to prevent the spread of fire or smoke or the passage of radiation.

door closer

A device for closing a door slowly, in some cases also locking it again. Special types of door closer enable the door to be held open at a certain position and also ensure that double-leaf doors close in the right sequence.

door closer delay mechanism

At an opening angle of about 70–120°, a valve reduces the closing speed in order to give disabled persons or those with bulky loads enough time to pass through the door. From about 70° onwards, the door returns to the preset closing speed.

door coordinator

A module in an automatic door mechanism for ensuring that the meeting stiles of a double door close in the right sequence. This prevents jamming of the door leaves.

door handle

A piece of door hardware used for opening and/or unlocking a door.

door pull

A horizontal or vertical rigid bar fitted to a door. Length, diameter, fixings and surface finish can be adjusted to suit the customer’s specification.


A rooftop structure that projects above a sloping roof surface and is usually finished with the same roof covering as the rest of the roof. Dormers permit the inclusion of vertical windows for rooms in the roof space.

double bevel

A type of edge working with two different chamfer angles along the edge of the glass.

double door with meeting stiles

In this type of double door the two side-hung leaves close against one another in the middle (there is no central mullion). Such double doors for traffic in both directions are frequently designed for right-hand traffic, with one leaf opening inwards, the other outwards.

double glass façade

Also known as double-skin façade. This is an additional transparent single-glazed glass envelope erected in front of an existing façade. The new outer leaf protects the building behind against wind, weather and overheating in the summer.

double thickness sheet glass

An old designation for glass 4 mm thick.

double window

An interim development between single glazing and insulating glass. The volume of air trapped between the two single-glazed windows functions as an additional layer of thermal insulation.

double-leaf façade

A façade with inner and outer leaves. The cavity between the two provides protection against the weather and solar radiation and ensures ventilation; if wide enough it can also be used for maintenance and as an escape route. Also referred to as a double-skin façade.

double-sided tape

An adhesive tape with adhesive on both sides which is used in assembly and erection.

double-skin façade

This is a double-leaf façade open to the outside. The sunshade in the cavity is protected by the outer leaf. Opening lights in the inner leaf enable the interior to be naturally ventilated.

downstand beam

This is a horizontal loadbearing member that projects below a suspended floor and transfers the loads to columns, walls or other loadbearing elements.

draft design

A presentation and visualisation of a project in the form of graphics, drawings and models which is used for checking and if necessary improving the quality, functions, etc., but also for detecting possible flaws in the design.


This is the collection and non-pressurised removal of rainwater, surface water or groundwater.

drawing agent

A grease, oil, soap or coating used to improve the surface properties of a workpiece and prevent tool wear.

drawn glass

A type of glass produced according to an industrial method employing electrical melting and mechanical, vertical drawing. Drawn glasses are fire-polished on both sides during the production process.

drilled hole

This is a standard process in the working of glass. A hole is drilled, or rather ground, in the glass with the help of special carbide-tipped drills or diamond-tipped crown drills. There is always a wasted disc of glass in the case of large diameters.

drilled hole in glass

It is possible to drill a hole of any diameter in glass, but the usual diameters are 4–6 mm. Drilled holes can be ground and polished internally for special applications. Minimum spacings and edge distances must be adhered to for safety and security glasses.

driving rain resistance

The ability of a window or façade construction to resist the infiltration of rainwater. DIN EN 12208 provides a resistance classification.

dry gasket glazing

The sealing of windows and façades by means of preformed elastic gaskets to prevent the passage of air and water.

dry lining/construction

Dry lining techniques do not use any building materials that contain water, e.g. concrete, plaster, for constructing components. Therefore, no drying times are necessary. All dry lining trades can follow each other in direct succession.

dual seal system

Effective and permanent sealing of insulating glass by providing a primary polyisobutylene seal and a secondary seal of polysulphide, polyurethane or silicone.


The capacity of a material to deform under load and dissipate stress peaks through yielding. Glass is not a ductile material. Local stress peaks, e.g. around drilled holes, are relevant for the design of the entire piece of glass.

duo-roof (plus-roof)

Existing conventional flat roofs can be refurbished by improving the waterproofing and adding a second layer of thermal insulation made from extruded polystyrene (inverted roof) to the existing roof finishes.

duopitch roof

The duopitch roof is the most common roof form in cold and temperate climate zones. It consists of two surfaces that slope downwards either side of the highest, horizontal edge, the ridge. Also known as gable roof.


File format for saving vector graphics.

earth connection

This is an electrically conductive connection with the earth. It ensures that all equipment, installations and systems are at the same potential as the surface of the earth. The system consists of earth electrodes, connecting cables and corresponding terminals. (US: ground connection)

earth pressure

The force that the soil exerts on building components in the ground or adjacent to made ground (e.g. basement walls). The magnitude of the earth pressure depends on the type and height of soil and the inclination of the building component with respect to a vertical line. Earth pressure has an effect on the design of building components that have to resist this pressure.


The eaves is the lower linear edge of a roof surface, where all the run-off water is discharged from the roof surface.

eaves overhang

This is the horizontal distance from the outer face of the external wall to the end of the eaves.


Ethylene copolymer bitumen is a polyethylene whose properties have been changed through the synthesis with bitumen. At low temperatures it exhibits an approximately elastic behaviour and better resistance to UV radiation and weathering; it can be bonded to hot bitumen. ECB is used as a waterproofing material, e.g. on roofs.

edge deletion

A glass coating is usually removed from the area of the hermetic edge seal by grinding, but this does depend on the particular coating system. Any grinding marks left on the glass can remain visible so that area of the glass can be distinguished from the coated area. This also applies to the overhanging glass pane of stepped insulating glass.

edge dip

Edge dip is the distortion of a pane of glass at the corner in particular.

edge distance

The minimum distance between a hole drilled in a component and the edge of that component. This is calculated by multiplying the hole diameter by a factor x (which depends on the material).

edge lighting

This is a method in which a matt or textured pane of float glass is illuminated from a glazing bead fitted with LEDs. This only functions when the edge of the glass where the LEDs are positioned is polished smooth. The light is distributed more or less evenly throughout the glass.

edge preparation

Preparatory work prior to producing a welded joint, which involves preparing the edges to be connected in a suitable way.

edge trim

Edge trims are used for capping, covering, stiffening and retaining other components. They are produced mainly from sheet steel, aluminium, copper, zinc or stainless steel in various thicknesses and many different colours.

edge working

seele can supply glass with any type of edge working to suit technical requirements or the customer’s specification. Edge working describes not only the actual form of the edge (straight, mitred, faceted or rounded), but also the finish. The types of finish range from cut-to-size to polished.

EFB sheets

Einheitliche Formblätter (standard preprinted forms) are part of the contract award manual of the Federal Ministry of Transport, Building & Urban Development. They are used by the client to appraise a quotation and as a basis for calculating the costs of additional work.


Abbreviation for European Foundation of Quality Management, a voluntary association at European level for promoting quality management. One focus of the association’s work is the regular self-assessment and appraisal of processes in companies and organisations.


This is a non-deformable but nevertheless elastically pliable plastic with a glass transition temperature below room temperature. An elastomer can deform elastically when subjected to tension and compression but then returns to its original form when the load is removed.

ELC steel

Abbreviation for extra low carbon. This is an austenitic CrNi steel that is used to prevent intergranular corrosion. Owing to its good formability, this type of steel is used mainly for screws, bolts, studs, nuts and rivets.

electric current

The flow of electric charge, which is measured in amperes (A).

electric glass panel heater

A fully transparent glass radiant panel heater offered as a straightforward plug-in system.

electric scissor lift

An elevating platform designed for interior applications which operates silently and without emissions. Such lifts are available with white tyres to prevent marking sensitive floors.

electrical conductivity

This describes the ability of a substance to conduct an electric current. Silver, copper and aluminium are good conductors of electricity.

electrical sheet steel

Cold-rolled thin sheet steel in thicknesses from about 0.20 to 0.65 mm alloyed with silicon (Si) and with particular magnetic properties. Electrical steel is characterised by its high magnetisability in an alternating magnetic field with minimal eddy current losses, i.e. it helps to save energy.

electrical steel

Steel produced in an electric arc furnace or (in the case of small amounts) in an induction furnace. An electric arc furnace functions in such a way that it enables the production of chemically resistant grades, high-speed steels, special steels for engineering, aircraft and nuclear technology, and magnetic materials.


The ability of molecules and crystals to change their optical properties upon the application of an external local electrical field, which influences the states of the electrons.

electrogalvanised sheet metal

In contrast to hot-dip galvanising, the layer of zinc on this flat product is applied with the help of an electrical field from the aqueous solution of a zinc salt.

electronic speed control (ESC)

This is a control technology used when extreme frequency accuracy is required. The frequency can be regulated within a tolerance of 0.5 Hz. However, a tolerance of 8% must be accepted for the voltage.


In this electrochemical process the parts to be polished are immersed in a special bath. Those parts are connected to the anode, whereupon the surface is dissolved in the electrolyte. This process is especially suitable for parts that cannot be mechanically polished (e.g. complex parts, thin-wall parts).

elevating work platform

This can be used to raise persons or goods to a certain height. Various types of operating mechanism are possible, e.g. hydraulic cylinders, spindle drive, pneumatic (bellows). Such platforms enable erection and installation work to be carried out at great heights.

elevation drawing

A (normally) scale representation of a vertical surface in a building, often an external wall. Such a drawing is either used to show the structure of a façade or serves as a vertical section through a building to show the internal layout of the floors and/or the internal walls.

elongation at rupture

This specifies the strain at which a material fails. For example, PVB exhibits an elongation at rupture of approx. 250 %. This means that the length of the material increases by 2.5 times before it fails. The elongation at rupture is usually only specified for elastomers and other, very extensible materials.

emissive power

This describes the ability of a surface to emit heat in the form of heat radiation or to reflect heat radiation. It is specified as a percentage or as a decimal value between 0 and 1. The following applies: the lower the emissive power of a surface, the greater it contributes to thermal insulation.


Euronorms (EN) are sets of rules that have been ratified by one of the three European standardisation bodies: either the European Committee for Standardisation (CEN), the European Committee for Electrotechnical Standardisation (CENELEC) or the European Telecommunications Standards Institute (ETSI).


This is a powdered material (frit plus metal oxides) that is applied to glass and subsequently fired for decorative purposes.

enamel coating

The enamelling process involves adding a ceramic layer to the glass prior to thermal toughening so that it fuses with the glass during the toughening process to form a new weather-resistant surface. The ceramic layer consists of finely ground glass and pigments.

enamelled glass

This is a thermally toughened glass type into which a coloured ceramic layer of enamel is fired during the toughening process. The enamelling can be applied to either the whole surface of the glass or just certain areas.


Industrial enamelling always consists of one or two ground coats plus up to five cover coats. The latter give the enamel its chemical resistance and the necessary service characteristics. The base material is usually fine-grained steel (e.g. P275 NH, P265 GH), the carbon content of which is limited.

enclosing square/rectangle

When cutting a non-quadrangular piece of glass, the calculation of the price includes the enclosing square/rectangle. For façade glazing with special shapes, this therefore results in a much larger area than the net façade surface area – a fact that must be taken into account when calculating the price.


The German Energieeinsparverordnung (EnEV, Energy Conservation Act) prescribes the standard requirements for efficient use of operating energy in a building or construction project in accordance with building legislation. The EnEV applies to residential and office buildings. The latest amendments were implemented on 1 October 2009.

energy performance certificate (EPC)

This describes the energy efficiency of a building.


The production of artefacts by way of industrial, craftsman-like or artistic methods and abilities.

engineering steel

Grades of steel that are used in the construction industry are sometimes known as engineering steels. DIN 17100 regulates and defines the classification of such steels.

engineering steel

This is a steel type for general purposes. According to EN 10027, engineering steel grades are prefixed with a letter E.


Ethylene-propylene-diene rubber (EPDM) is an elastomer. This rubber material is used as a sealant in glass assemblies because of its excellent durability. EPDM exhibits a high thermal shock resistance and is weather- and moisture-resistant.

epoxy resin (EP)

This consists of polymers that produce a thermosetting plastic with high strength and good chemical resistance when a suitable hardener is added.

erection instructions

Erection instructions describe the complete assembly of individual parts to form a building component. Apart from the assembly sequence, the instructions include further information for the erection crew (e.g. setting blocks, attaching foil, tests to be performed, etc.).


Abbreviation for European Technical Approval. The verification of the usability of a construction product according to the German construction product directive.

ETAG 002

European Technical Approvals Guideline for structural sealant glazing systems. This document regulates the procedure for gaining approval for certain types of glass constructions employing adhesives. The tests and analyses are to a large extent based on the use of silicone adhesives. This and other ETAGs are drawn up by the European Organisation for Technical Approvals (EOTA).


The abbreviation for ethylene-tetrafluoroethylene. ETFE sheets exhibit a very low self-weight plus high light and UV transmittance. In architecture ETFE sheets with a thickness of 50–250 µm are used primarily for tension structures. EFTE sheets can be printed.

ETFE cushion

ETFE sheets exhibit a very low self-weight but at the same time a high light and UV permeability. In architecture ETFE sheets with a thickness of 50–250 µm are used primarily for tension structures. For example, the roof and façade to the Allianz Arena football stadium in Munich were constructed from 2760 individual ETFE cushions.


See: external thermal insulation composite system.

ex works

One of the most important international rules for conventional forms of contract. Term of sale signifying that the price invoiced or quoted by a seller includes charges up to the seller’s premises only. All charges from there on are to be borne by the buyer (see also FOB, DDU, DDP).

exfoliation corrosion

This is a form of layer-by-layer selective corrosion which, depending on the alloy, takes place in a transgranular or intergranular form and in vulnerable areas preferentially progresses in planes parallel to the plane of rolling. The flaking of the surface is due to the corrosion products that form.

expanding foam

A foam material supplied in a spray can and used for filling gaps and fixing elements such as doors and windows.

expansion joint

See: movement joint.

expenses allowance

This is paid for domestic and foreign business trips where more than 8 working hours in one day are involved. The amount of this allowance depends on the particular country. It can be deducted before payment of tax and social security contributions. (The exceptions are regular travel days, which are added together and no longer deductible for 90 days or more; when there is an interruption of 4 weeks between the destinations, the 90-day limit begins again.)

external thermal insulation composite system

Such a system is used for insulating the external walls of buildings.

extract-air façade

An extract-air façade is a special type of double-leaf façade. Here, the air in the cavity between the two leaves and the interior requiring ventilation are linked via openings in the inner leaf. Mechanical fans expel the waste air vertically upwards through the cavity.


In the extrusion process a synthetic material is forced through a die that creates the desired final form (foil, sheets, plates, tubes and sections).


A versatile method suitable for processing the majority of thermoplastics. A continuous ribbon of plastic granulate heated close to its melting point is forced through a shaped die and the ensuing form subsequently cut to size and cooled. Sheets, sections, tubes and plates can be produced using this method.


A hot-working process that produces sections or tubes from solid or pre-hollowed steel material. The red-hot raw material is fed into a barrel and forced through a die with the appropriate cross-section.

F glazing

This type of glazing prevents the passage of flames, heat radiation, smoke and fumes. It becomes opaque in the event of a fire.

fabrication planning

The process of providing the geometrical framework conditions and the structural designs of the components in the form of drawings and/or tables so that the fabricator can manufacture the individual parts of the structure.


A generally vertical or near vertical outside wall to a building, often with a special decorative or ornamented design.

façade access system

This is a permanent installation used for inspecting, cleaning and maintaining a façade which owing to its size cannot be accessed by other non-permanent installations. Such systems consist of cradles, movable ladders and horizontal rails that are fixed outside the façade.

façade consultant

A specialist who advises (usually) the architect or general contractor on all issues concerning façades.

façade cradle

A cradle suspended from the roof is useful for façade and roof geometries with some degree of complexity (e.g. projections, acute building angles). A slewing mechanism on the jib enables the cradle to be aligned parallel with the façade at all times and enables façade surfaces behind projections to be reached.

façade element

A part of a façade that is factory-assembled to form a completely watertight and vapour-tight glazing unit and on site can be attached to an existing support system without the need for additional work. In the case of particularly large façade elements, the glazing can be carried out on site in the installed condition.

façade maintenance system

This is a permanent installation used for inspecting, cleaning and maintaining a façade which owing to its size cannot be accessed by other non-permanent installations. Such systems consist of cradles, movable ladders and horizontal rails that are fixed outside the façade.

façade with ventilation cavity

This type of façade is a multi-layer external wall design in which the outermost layer, which provides protection against driving rain, is separated from the layers behind by an air space.


A glass edge with an angle other than 90°.

facility/facilities management

The term facility management (FM) covers all aspects of the management of buildings, plants and establishments. It is a strategic management approach designed to ensure that buildings and their systems, processes and contents remain available and continue to function. We distinguish between business, physical assets, services and process management. Facility management also includes, in particular, the maintenance of and repairs to parts of the building such as roofs and façades.

fair-face concrete

Concrete that is not covered in any way (render, cladding, etc.) and whose exposed surfaces usually have to serve an aesthetic function and achieve a certain appearance.

fall arrest system

A fall arrest system is designed to prevent people falling from, for example, ladders or roof surfaces. Such systems may be in the form of horizontal and/or vertical anchor rails and/or individual anchor points. The person requiring protection wears a safety harness that is connected via a special safety line to a rail or anchor point.


Fatigue occurs when components are subjected to frequent, cyclic loading. In this case verification of durability will be required, which guarantees the durability depending on the loads, loading cycles and number of cycles. Wind loads are not generally regarded as cyclic loads.

fatigue/endurance limit

The fatigue limit designates the long-term cyclic loading of a material or component without the material or the component being damaged.

feather edge

An edge form that for constructional reasons forms an angle deviating from 90°; the acute angle is arrissed max. 2 mm.


The abbreviation for finite element method, a technique for analysing complex loadbearing structures. The complexity of some forms of modern architecture means that this is sometimes the only way of carrying out the structural analysis of a design economically. Experience is necessary for the implementation of this method and the interpretation of the results.

fenestrate façade

This is an external wall, usually of concrete or masonry, with individual, discrete openings for doors and windows. Such an external wall is usually also part of the primary structure of the building.

fibre-reinforced plastic

A composite material consisting of a polymer matrix reinforced with fibres.

filiform corrosion

A thread-like form of corrosion that occurs beneath organic coatings. It is caused by flaws in or mechanical damage to the coating. The coating becomes detached from the substrate, forced upwards by the corrosion products that form.

filigree architecture

seele carries out all the processes necessary for the realisation of filigree steel-and-glass structures, from planning to erection. The combination of steel, aluminium and glass results in buildings flooded with daylight.

filter drain

This is a gravel-filled trench (which may also contain a porous pipe) for collecting and draining surface water (rainwater). Such drains are used wherever soil sealing is prevalent. Also known as rubble or French drain.

final cleaning

The contractually agreed cleaning of a façade prior to handover to the client.

fine-grained steel

A readily weldable engineering steel with a high yield stress.

fire resistance

The ability of a building material to form an effective barrier to the spread of flames, smoke and fumes and/or prevent the transmission of heat radiation.

fire resistance rating

Fire resistance ratings are designated by the letter T for doors and F for fixed glazing followed by the time (in minutes) the construction can withstand the fire.

fire stop

This is usually made from relatively soft materials. This term is usually applied to a bulkhead made from layers of rock wool treated with a fire-resistant coating. A fire stop can also be made from a hard material such as fire-resistant mortar.

fire wall

Fire walls divide a building into fire compartments. In the case of a soft roof covering, a fire wall must also continue above the roof.

fire-resistant glazing

A glazing system (including frame, seals and fixings) that prevents the passage of flames, fumes and smoke for a certain length of time, but does not prevent the passage of heat radiation and hence the risk of self-ignition of any objects on the side of the glazing not directly exposed to the fire.

fire-resistant window

A fire-resistant window is a window element that owing to its overall construction (consisting of frame, glazing, seals, fixings, etc.) can withstand the effects of fire for a certain length of time. Such windows are classified according to the function of the glass used (fire-resistant glass) and the fire resistance rating required.


The Fachverband Konstruktiver Glasbau e.V. (Trade Association for Glass in Construction) is a collaboration between education establishments and industry for promoting R&D projects. The FKG takes part in the preparation of guidelines, stipulations and standards, encourages the exchange of information among its members and undertakes PR work.

flashed glass

This type of glass consists of a primary glass product (backing or substrate) and one or more layers of coloured or obscured glass.

flat roof

According to German legislation a roof is classed as a flat roof when the pitch with respect to the horizontal is < 10°.

flex levelling

A form of pretreatment used to prevent stretcher strains in stored sheet metal. The sheet metal passes through a flex leveller prior to forming and this results in a plastic prestress comparable to a low degree of cold rolling.

float glass

This is sheet glass produced using the float glass method. This type of glass accounts for about 95% of the entire sheet glass output for all applications such as windows, vehicles and mirrors.

float glass method

The most common type of glass production these days. The glass melt at a temperature of at least 1100 °C cools down to such an extent while floating on a bath of molten tin that at the end of this process it can be withdrawn in a solid form. The float method guarantees high-quality, distortion-free glass with parallel surfaces.

floating screed

The most common type of screed for residential and office buildings. A floating screed is laid on impact sound thermal insulation and has no direct connection to the structural floor below. This prevents the transmission of sound or heat to other parts of the building.

floor-mounted door closer

This device closes a side-hung or swing door – also fire-resistant designs – made from any material, in any weight.

flush glass fixing

A special type of point fixing that on the outside finishes flush with the surface of the glass. Countersunk point fixings require thicker glass than fixings with a conventional head. The advantage is a flat surface for easier cleaning.


Free on board. Term of sale under which the price invoiced or quoted by a seller includes all charges up to placing the goods on board a ship at the port of departure specified by the buyer. The buyer bears all the risks of further handling and costs (e.g. transport, customs clearance) up to delivery to the final destination. One of the most important international rules for conventional forms of contract (see also ex works, DDU, DDP).

fogged glass

Tarnishing, age-related corrosion phenomenon, mostly a coating on the surface of the glass (mirror). In the case of insulating glass, fogging is frequently caused by a breakdown in the hermetic edge seal.

folding door

With this type of door the individual leaves are connected by hinges and suspended from a track. If the door is to operate properly, the hinges must line up exactly with the track. When open, the door leaves are stacked together at the side of the opening.


Hot-forming with hammering or pressing tools without permanent strain hardening.

forging temperature

The forging temperature is about 80 % of the melting point of the material used, e.g. 500 °C for aluminium alloys and 1200 °C for unalloyed steels.


This is the capacity of a material to change its form plastically without discontinuity.


A structural element that transfers the loads of the structure to the subsoil. Plain or reinforced concrete are the materials most often used for foundations.


This is the first phase of the glass melting process, the melting of the raw materials until the complete mass is transparent.

four-point bending test

This test is used to determine the bending strength of flat pieces of glass. The advantage of this test over the three-point bending test is that the same moment load prevails over a wide region and therefore the failure is not inevitably at the point of maximum moment in the centre of the glass.

Fourcault process

In this process sheet glass is drawn vertically and directly out of the melt through a ceramic die. The thickness of the glass is adjusted by changing the drawing speed. This process was registered for a patent for drawn glass manufacture by Emile Fourcault in 1904 and has been used on an industrial scale since 1913.

fracture pattern

The arrangement of the cracks in a broken pane of glass. Fracture patterns vary depending on the type of glass. Toughened safety glass, for example, breaks into a large number of small fragments, heat-strengthened glass into large fragments. The standards demand certain fracture patterns for toughened safety and heat-strengthened glass.

frame construction

One form of loadbearing structure for a building. The loadbearing structure is made up of individual linear elements assembled to create a primary structure for carrying the loads.

frame construction

One form of loadbearing construction in architecture and building engineering. The framework of the construction is made up of elements with a primary loadbearing function.

frame seal

A peripheral preformed strip made from an elastic sealing material in the window frame which separates interior from exterior by way of a cavity. There is an additional overlap seal in the frame to the opening light.

framework contract

This is an agreement between legal entities or natural persons, e.g. a collaboration, an employer-employee relationship or a deal between seller and buyer. Such contracts are usually agreed in order to regulate fundamental aspects of the cooperation, but still allow freedom for individual situations.

free form

A free form can be either two- or three-dimensional. A free-form surface cannot be described by a mathematical formula. Free-form surfaces for buildings and structures require considerable modelling input and place great demands on designers and builders.

fretting corrosion

This is a special form of corrosion where in the absence of corrosive media and in dry ambient conditions a material conversion process takes place at the surface of the metal which is caused by the minimal relative movement of two surfaces in rubbing contact. A characteristic feature of this type of corrosion is a black discolouration at the point of corrosion.

friction welding

In this welding method the heat generated by friction is used for welding. To do this, one of the parts to be connected is rotated in a friction-welding machine and then pressed against a stationary part.


Fulgurite is sand that has solidified to glass after a lightning strike.

full mortise lift-off hinge

This type of hinge is suitable for wooden doors and frames only; it is let into the door leaf on one side, the door frame on the other. It is made up of two parts: a lower flap with a pin and an upper flap with a tube to accommodate the pin. The two flaps are either aligned or offset at a right-angle and rolled over to accommodate the pin.

fully adhesive-bonded prefabricated façade

A type of façade in which the panes of glass and their frames are pre-assembled to form a unit and then attached to the supporting structure by means of adhesive.

functional glass

Besides light transmittance and a view through, functional glasses also fulfil other functions: low E glasses reduce the transmission of heat, solar-control glasses protect against excessive overheating, acoustic glasses protect against noise, fire-resistant glasses prevent the spread of fire, safety and security glasses protect against intruders and injuries.

fused quartz

Another name for quartz glass


see “fusingglass”

fusing (glass)

In this process various pieces of glass are melted together. One advanced application of this process is the production of large self-supporting panes of glass. seele has perfected the fine art of producing self-supporting panes of glass to satisfy the very highest demands.

fusing glass

In the fusing process pieces of glass, plus an appropriate coloured glass coating if required, are fused onto a primary glass product in a fusing furnace. Fusing glass panes or fusing artefacts are the result.


Abbreviation for “for your information”; e-mails are often forwarded with this abbreviation.

G glazing

This type of glazing prevents the spread of smoke and flames, but cannot prevent the passage of heat radiation. It remains transparent in the event of fire.


The total energy transmittance (g-value) is the sum of the direct transmission due to solar radiation and the inward heat emissions due to radiation and convection. Double glazing made from clear glass has a g-value of approx. 0.8.


Gemeinsamer Ausschuss Elektronik im Bauwesen (Joint Committee for Electronics in Building). See: www.gaeb.de.

GAEB file

Electronic file for exchanging specifications and quotations according to standards laid down by the GAEB.

GAEB format

Electronic data format for exchanging specifications and quotations.


This is a trade name for strip or sheet steel with an anti-corrosion surface finish. The finish in the form of an aluminium-zinc alloy is applied to the surface of the steel in a hot-dip process. The zinc melt normally contains 5 % aluminium and approx. 0.1 % so-called misch metal.


This is a trade name for strip or sheet steel whose surface has been coated with a special aluminium-zinc alloy. To apply the coating, the steel is dipped in a bath containing 55 % aluminium, 43.5 % zinc and 1.5 % silicon.

galvanic corrosion

This type of corrosion occurs when different metals are in contact in the presence of a corrosive medium. In all cases the less noble metal corrodes.


The application of a thin layer of zinc to steel to protect it against corrosion.


When hot-dip galvanised strip or sheet steel is annealed following galvanising (at temperatures above the melting point of zinc), the resulting product is known as galvanneal; the process is called galvannealing.

gasket glazing

A method of glazing without silicone. Instead, preformed sealing profiles are used, their particular form depending on the system. Also known as gasket or dry gasket glazing.

general tolerances

These tolerances apply to dimensions for which no specific tolerances are specified (untoleranced dimensions). They are divided into nominal size ranges and tolerance classes.

Georgian bar insulating glass

Small-format insulating glass units, like those used for Georgian bar insulating glass windows, are subjected to higher physical loads than large-format insulating glass units, which can compensate for the bowing and dishing via the elasticity of the pane of glass itself.


Abbreviation for glass-fibre reinforced plastic. GFRP is a fibre-plastics composite made from a synthetic material (e.g. polyester resin, epoxy resin or polyamide) and glass fibres. It is colloquially referred to as fibreglass. With the help of GFRP, seele can realise unusual contours in the form of panels (e.g. Unilever House in London).


Glass is an inorganic product made from various molten raw materials and upon cooling does not crystallise, but rather gradually solidifies. In thermodynamic terms, glass is regarded as a frozen, supercooled liquid.


The word glass is derived from the Germanic word glasa. Glass is one of the oldest materials known to humankind, but some of the issues regarding its atomic composition and structure have still not been fully resolved.

glass balustrade

This is a balustrade with an infill panel of glass or acrylic sheet. The handrail can be made from stainless steel, wood or aluminium. The glass is often fixed in vertical posts at the sides, but can also be fixed at the base.

glass bead blasting

This is a method for cleaning and also finishing surfaces. It is used for stripping paint and similar coatings, also for removing welding or soldering slag. This method is also very good for removing temper colours and layers of oxide from non-ferrous metals, stainless steel, cast iron or cast aluminium.

glass beam

A (mostly) horizontal glass component that can accommodate shear forces and bending moments. Experimental setups have resulted in enormous load-carrying capacities over spans of several metres. Glass beams ensure maximum transparency for roof glazing. Their use as a secondary structure results in enhanced requirements for the residual loadbearing capacity.

glass blind

A glass blind is an erroneous name for a blind that is fitted between the panes of an insulating glass unit. Such a blind is not made of glass, of course. This is in contrast to glass blinds in furniture, where roller shutters or louvre blinds can be fitted to various kitchen cupboards.

glass block

This is generally a hollow glass unit made from two open, pressed shells fused together. The two outer surfaces may be smooth or textured. Glass blocks are available in various formats and colours.

glass block

The traditional glass block is made from pressed glass. Glass blocks can be used to construct transparent, translucent, straight or curving walls. seele has redefined the glass block by laminating individual panes of sheet glass. The use of coloured plastic sheets, sandblasting methods, etc. enables a variety of effects to be achieved.

glass block paving

This material is used for producing special suspended floor elements. It is a form of construction in which glass is placed in a frame of in situ or precast concrete and permanently connected to the concrete.

glass breakage

Glass is a brittle material and is characterised by the fact that it breaks directly when overloaded. Unlike, for example, metals, it has no yield point.

glass bridge

The glass bridge designed by seele consists of 4 mm thick bent glass panes with a total thickness of just 3.7 cm for the complete glass element. The highly transparent, curved bridge of cold-formed glass with a span of 7 m weighs 1.7 t in total and can carry a load of up to 7.2 t.

glass ceramics

Glass ceramics are produced in a glass technology process and initially solidify on cooling to form glass. Subsequent heat treatment transforms this glass into an essentially crystalline material. Glass ceramics exhibit properties that differ from those of the glass from which it was made.

glass coating removal

The removal of a coating from a pane of glass in the vicinity of the edge seal. One reason for this is to ensure a reliable bond. Also known as edge deletion.

glass colorant

The majority of types of glass are produced with further additives in order to influence certain properties, e.g. the colour of the glass. Minute quantities (e.g. 0.1 %) of metals are added to the melt to colour the glass. Gold and silver are the metals used most frequently.

glass corrosion

This begins with the leaching of oxides from diverse elements, e.g. sodium, potassium, calcium, barium or boron. The physical properties of the material therefore change at the places affected. A layer of gel forms which reacts with ions from the active substance to form an opaque coating.

glass cutter

A tool for cutting glass. Actually, this term is erroneous because the glass is only scored and then snapped. In the past, a diamond was used for scoring, these days a small steel wheel.

glass cutting

The commonest method of cutting glass is to score the surface with a glass cutter and then snap the glass along this line.

glass defects

The defects caused by the production, the numbers of which are specified in the respective standard for the glass. There are optical and visible defects depending on the type of glass.

glass door

A door with a glass door leaf with or without a perimeter frame. Such doors are made from toughened safety glass.

glass door

Safety glass is used for frameless all-glass doors. The glass door leaf is highly resistant to breakage and impacts.

glass door hinge

This is a special type of hinge for use with glass doors. The (safety) glass of the door must be factory-drilled in order to attach the hinge.

glass fibre

This is a long, thin fibre drawn out of the glass melt.

glass fibre-reinforced aluminium

Abbreviated to GLARE, this is a new type of composite material consisting of many plies each just a few tenths of a millimetre thick. The plies alternate between aluminium and a glass-fibre laminate (glass fibre-reinforced plastic) and are bonded together under pressure.

glass fin

A mostly vertical, stiffening glass beam element found in façades. It is used to brace a glass façade.

glass for building purposes

A material made from quartz sand, soda, limestone and dolomite. Glass is a mixture of various silicates and has a large softening range but no fixed melting point. When it cools from its fluid phase it remains plastically deformable down to a temperature of about 500 °C.

glass goblet

We are pretty certain that seele did not create the world’s oldest work of glass (art)! The oldest glass vessel that can be reliably dated is a goblet bearing the name of the Egyptian pharaoh Thutmose III, which was made around 1450 BC.

glass grinding

The microstructure of glass does not permit the use of cutting-type machining operations. Therefore, unlike when working with metal, glass grinding is therefore not a cutting operation, but rather a process that forces and rips out small particles. Glass can only be ground wet.

glass in building

Glass is a very popular, very common material in modern architecture. Glass hardly ages and requires a little maintenance, apart from cleaning. Filigree architecture thrives on the extensive use of this material. Glass can also satisfy structural requirements to a certain extent.

glass lifter

A tool for moving and lifting panes of glass. The vacuum created by evacuating the air between the suction cup and the flat surface of the glass ensures that the tool remains attached to the glass. Glass lifters are used to tilt, turn and position panes of glass during installation.

glass manufacture/production

We distinguish between float glass and rolled glass production. These days panes of glass are manufactured almost exclusively by means of the float glass method developed in the 1960s. In the technical regulations and standards this type of glass is also referred to as polished plate glass.

glass mat-reinforced thermoplastic (GMT)

A synthetic material in which glass-fibre mats are bonded together by and enclosed in a thermoplastic material.

glass melt

This comprises various phases. The initial melting of the raw materials (founding) is followed by the homogenisation phase and then the refining phase in which all bubbles are driven off. Finally, there is the cooling phase, in which the material cools ready for further processing.

glass melt bath

This is used for producing the glass melt in the manufacture of glass. The raw materials for the glass in the bath are constantly replenished and combine to form the melt. This process can last several days.

glass properties

Glass is neither combustible nor flammable and therefore cannot give off any smoke. Glass has a homogeneous, smooth surface, is easy to clean and therefore very hygienic. Glass has a very high chemical resistance and withstands the majority of acids and alkalis, is insoluble in water and essentially corrosion-resistant.

glass rack/racking

Frame for storing and transporting panes of glass or complete window elements upright. Usually fitted to the outside of a vehicle, but can be fitted inside.

glass roof tile

A pressed glass product in the form of a clay or concrete roof tile which is used to admit daylight into roof spaces.

glass safety barrier

This is a glazing element designed to prevent persons falling from a higher to a lower level. Vertical glazing, glass spandrel panels with a continuous handrail and glass balustrades all fall under this definition.

glass sliding door

This is a sliding door made of glass, usually without a frame. Such doors can be used wherever a high degree of transparency is desired.

glass stair/stairs/staircase

A self-supporting staircase made entirely of glass. Multiple laminated glass panes with SentryGlas® (SG) interlayers are often used here because of their good load-carrying capacity. These form both the primary and secondary structures of the staircase. Metal parts are used only for connecting elements between the panes of glass. SentryGlas® is a trade name of DuPont™.

glass surface designation

In order to be able to describe the position of a coating on a surface of an insulating glass unit, the surfaces of the individual panes of glass are numbered consecutively from outside to inside. The outer surface of the outer pane is therefore surface No. 1, the inner surface of the inner pane No. 4 (double glazing) or No. 6 (triple glazing).

glass test

Testing a piece of glass under in situ conditions.

glass thickness calculation

The sizing of sheet glass taking into account the dimensions, position, supports and/or fixings and the action effects to which the glass is subjected (e.g. wind pressure, knife-edge loads, etc.).

glass transition

This is the temperature range (transformation range) within which the mechanical behaviour of glass changes radically.

glass transporter

Glass transporters are specially designed heavy goods vehicles in which the sensitive glass is clamped in place hydraulically. These vehicles enable base glass products with the standard ribbon size to be transported vertically without the need for any special transport permits. Such vehicles can also be used for transporting other large-format panel-type elements.

glass treatments

Subsequent treatments for primary glass products include attaching plastic foils, edge working, engraving, etc.

glass tube

Made from special tubular glass, the thickness of this component can be varied to suit its purpose. Today, exclusively mechanical methods are used to produce glass tubes by means of horizontal or vertical drawing methods. Glass tubes can be used as loadbearing elements.

glass-and-steel construction

This type of construction is generally delicate and lightweight in appearance. Such designs have enabled entire transparent façade areas to be constructed for the first time. Glass-and-steel façades have in the meantime replaced the fenestrate façade for commercial structures.

glass-and-steel roof

In a glass-and-steel roof the loads are carried via a trussing effect. The glazing constitutes the upper chord in compression. The lower chord and the infill bars are of steel. This type of construction results in very delicate and transparent roof structures. Special attention must be paid to the residual loadbearing capacity and transfer of loads into the panes of glass.

glass-and-timber construction

The large double-leaf façades designed and constructed by seele for Elm Park in Dublin represent a successful combination of timber beams, structural steelwork and aluminium sections. Timber structures can be glazed just as easily as steel or aluminium ones, provided the particular characteristics of timber are taken into account.


A method of producing glass with a blowpipe. This method is still used for producing many coloured and special glasses or for artistic purposes.


A biennial international trade fair covering everything to do with glass. All aspects of glass production, processing and treatment are presented. One special feature is the presentation of innovative forms of structural glazing. seele, known as an innovator in this field, is always present with impressive exhibits.

glasstec Innovation Prize

seele was awarded this prize at the glasstec trade fair in 2008 for its curved bridge of cold-formed glass with a span of 7 m. The innovative cold-forming method made it possible to bend glass spanning 7 m without the application of heat for the first time.

glazier’s lead

This is a mixture of lead and tin for lead cames which are used as the frames in leaded lights or for artistic purposes.


The process of installing a glazing element in its supporting construction.


The installation of glass in doors and windows plus the fabrication of independent components such as glass roofs, glass walls, etc., made from glass or plastics.

glazing bead

The glazing bead presses the pane of glass against a linear supporting member. Glazing beads can be nailed, screwed or clipped in place. The advantages of using glazing beads is the fast installation of the glass and its simple removal in the case of repairs. The disadvantage is the visible width of the frame construction.

glazing edge cover

This is the width of the pane of glass that lies within the clamping construction, e.g. a patent glazing wing. Depending on which standard applies, a minimum glazing edge cover may need to be guaranteed for a certain loading.

glazing for constant foot traffic

Glazing designed to function as part of a circulation zone. Glazing for constant foot traffic must satisfy high demands regarding loadbearing capacity and residual loadbearing capacity. The glass must have a non-slip surface. Thick panes of glass and multiple laminations (to ensure residual loadbearing capacity) are normally required.

glazing for constant foot traffic

Glazing intended for constant foot traffic must be made from laminated safety glass with at least three panes. The uppermost pane may not be taken into account for loadbearing purposes because it is directly exposed to mechanical damage which reduces its strength; it serves only to protect the loadbearing panes below and should be made from toughened safety glass.

glazing for limited foot traffic

Glazing designed to accept loads due to a limited number of specially trained people. One example is roof glazing that is only accessible for cleaning purposes. This glazing does not have to satisfy such stringent requirements as glazing for constant foot traffic.

glazing for redirecting daylight

Insulating glass with louvres in the cavity for redirecting the incoming daylight.

glazing gasket

Gasket profiles that are joined at the corners by vulcanisation to form a (normally) rectangular, watertight or rather vapour-tight, corner joint for a glazing element.

glazing/glass size

This is the size of a piece of float, rolled, plate glass etc. cut from stock or ribbon sizes.

glued laminated timber

This consists of at least three laminae glued together with the grain (fibres) of each layer parallel. Glued laminated timber is primarily used for engineered timber structures (e.g. roof trusses). Often abbreviated to glulam.

golden ratio

Regarded as the ideal proportion in mathematics and the arts. The ratio is approx.1:1.618. Corresponding subdivisions are regarded as very harmonious and aesthetically pleasing. Also known as golden section or golden mean.

green tinge

The natural greenish colouring of soda-lime-silica glasses, caused by the small quantities of iron oxide in the raw materials. Green tinge is not a flaw.

greenhouse effect

This effect ensues when solar radiation enters a room through glazing (windows or roof) and is absorbed by the materials in the room. This can cause the interior to heat up to temperatures well above those of the surroundings.


A lattice structure made up of a (mostly) large number of different individual elements. Expensive and time-consuming production and erection requirements. Special attention must be given to the design of the nodes. Computer-aided manufacturing (CAE) is essential with such complex projects.

grooved pin

A connecting pin with longitudinal grooves in its circumference. Depending on the particular application, these grooves can have different forms: half-length parallel grooves, half-length central parallel grooves, full-length tapered grooves, part-length tapered grooves. The grooves ensure that the pin remains firmly in place even in very smooth holes, even in the case of dismantling.

gross density

This is the density of a porous solid based on its volume including the pores.


A high-strength, non-shrink mortar with cement as the binder. Very high-quality grouts exhibit exceptional flowing properties even with a solids-to-water ratio of 10:1 (by weight).

GSB International

An organisation committed to upholding and improving the quality of coated building components for external use. The GSB quality regulations apply to the coating of building components made from aluminium and steel and its alloys which are used in the building industry.

guard rail

This prevents persons falling from a higher to a lower level. The uprights (posts) to a guard rail can also help to stiffen the treads of a stair. A guard rail must be able to withstand the lateral load of a person.

gutter heating

Such a heating installation can be fitted in the bottom of a gutter. It ensures that the base of the gutter is always kept clear of ice and snow so that meltwater can drain away unhindered. The self-regulating electrical heating installation is controlled via temperature and/or moisture sensors.


German abbreviation for friction-grip connection (gleitfeste, planmäßig vorgespannte Verbindung). In this type of connection the mating faces between the two components can be used to transfer forces via friction. Friction-group connections always require the application of a preload to the fastener and corresponding pretreatment of the friction faces.


German abbreviation for close-tolerance friction-grip connection with preload (gleitfeste, planmäßig vorgespannte Passverbindung). The load-carrying capacity is higher than that of a standard friction-grip connection without close-tolerance bolt. The application of a preload makes additional retainers superfluous.

gypsum board

A building product made from gypsum, mostly used in the form of plasterboard (GKB) with a layer of cardboard both sides for dry lining or acoustic purposes. The layer of cardboard both sides accommodates tensile forces and gives the board its stability.


A large hot-rolled steel section with wide or very wide flanges.

H-type tensile test specimen (SG)

Such a test specimen is used to assess the curing, adhesion and strength of an adhesive used in a structural glazing façade, for instance. The test should be carried out at least once for every combination of catalyst and base used. A new test is required every time a new container is opened.

hairline crack

A miniscule crack in a glass surface that is hardly perceivable and only becomes visible in a glancing light.

Halfen channel

This is used to attach loads to reinforced concrete components. The channel is placed in the formwork prior to concreting and then cast in permanently. Such channels must be planned at an early stage so that they are delivered to the building site in good time. The channel has a C-shaped cross-section and anchors on the back to secure it in the concrete.

hand sample

A small-size specimen of a coating, section, glass, hardware or other item for the client and/or architect. Produced in a handy size, usually A4 or A3. Such samples are usually required for approvals.


The handrail to a balustrade finishes off the top of the infill panel and is primarily fitted for safety reasons. Adjacent to a stair a handrail must be at least 900 mm above a line joining the nosings of the treads and there must be a clear distance of 40 mm between the handrail and any wall behind so that it is possible to grip the handrail properly.

hard glass

Chemically resistant and thermally stable apparatus glass with a high glass transition temperature and a coefficient of thermal expansion < 6 x 106 1/K.

hard impact

This is a test method for assessing the strength of glazing when subjected to the impact of a body with a relatively low mass (normally a steel ball) but high velocity. This test can be carried out, for example, on overhead glazing in order to simulate the impact of a falling object such as a tool.

hard/online coating

Hard coating is a method of coating that is carried out directly during the manufacture of float glass, with the coating substance being applied and fired while the surface of the glass is still fluid. The ensuing hard surface is resistant to the effects of chemicals and abrasion.


This process involves heating a material to the hardening temperature (also known as austenising) followed by cooling at such a speed that a considerable increase in hardness occurs, either superficial or radical, due to martensite formation. Hardening of steels is a very common heat treatment method.

hardening and tempering

A heat treatment method comprising hardening, quenching and subsequent reheating (tempering). Water, oil or air can be used as the quenching medium following hardening.

hardening of steel

This process increases the mechanical resistance of the steel through the specific alteration and modification of its microstructure. It can be achieved by way of heating with subsequent rapid cooling. If a metal is plastically deformed, dislocations spread throughout the workpiece.


A material’s resistance to deformation. The hardness of a material enables us to surmise its strength. Various hardness test methods can be used to determine the hardness of a material.

harmonised document (HD)

A European standard (EN) that has been drawn up on behalf of the European Commission and the EFTA secretariat in order to support the essential requirements of a European directive.


Designation for a German wide-flange I-beam with parallel flanges.


This is a form of energy produced through the conversion of other forms of energy. When a hot and a cooler body come into contact, the quantity of energy that flows from the former to the latter is known as heat. This increases the internal energy of the cooler body. Mechanical work too – not only heat – can increase the internal energy of a body.

heat capacity

This is a term from thermodynamics and designates the capacity of a body to store energy in the form of heat. It is generally represented by the symbol C. By definition, C specifies the quantity of heat Q (in joules).

heat conduction

This is the exchange of thermal energy between neighbouring particles or layers of a building component. Heat conduction depends on the thermal conductivity. The lower the thermal conductivity, the better is the insulating effect.

heat flow

This is the thermal energy (measured in watts) that passes through a certain area of a certain material with a certain thickness.

heat of fusion

This is the energy required to transform a material specimen from the solid state to the liquid state. In doing so, the bonding forces between the molecules or atoms are overcome without increasing their kinetic energy and hence their temperature.

heat transfer

There are three forms of heat transfer: conduction, convection and radiation.

heat-resistant glass

Glass ceramics with a slightly yellowish colouring. Normally used in stoves or as a spark guard in front of an open fireplace. This type of glass can normally resist temperatures up to 700°C.

heat-soak test

An additional thermal treatment for toughened safety glass following the toughening process itself. The aim of this test is to reduce the risk of spontaneous failure of the glass due to nickel sulphide inclusions.

heat-soaked toughened safety glass

This is a monolithic safety glass with a very high quality. Following the toughening process, the toughened safety glass is subjected to a special heat-soak test, which involves storing the glass for at least four hours at a temperature of 290°C.

heat-strengthened glass

This is a type of glass that has been subjected to a thermal treatment. The bending strength of heat-strengthened glass lies between that of float glass and toughened safety glass.

heated façade

As a rule, a heated façade comprises hollow sections that in addition to carrying the loads are also filled with water, not unlike a standard radiator, as a heat transfer fluid. The advantages of a heated façade are the even emissions of thermal energy and the decrease in the zones of cold air adjacent to the façade.

heated glass

A further development of laminated safety glass. It is heated by virtually invisible electrical wires. Depending on requirements, two or more panes of float glass are bonded together with PVB sheets.

heavy sheet steel

Individual or combined plates of any steel grade rolled on a four-high mill – the opposite of continuously rolled steel strip.

heavy sheet steel

Sheet steel with a thickness of 3 mm and more. Heavy sheet steel can be supplied in practically all unalloyed and alloyed steel grades.


A very common mineral from the mineral class of the oxides (and hydroxides) and a modified form of iron (III) oxide with the chemical formula Fe2O3.

hermetic edge seal

In insulating glass units the cavity between the panes is maintained by a peripheral, sealed spacer, the hermetic edge seal. The edge seal generally consists of a spacer profile made from aluminium, stainless steel or plastic which is bonded to the glass with a polyisobutylene adhesive.

high-temperature steel

A type of steel that exhibits good mechanical properties (creep limit, creep strength, relaxation resistance) at temperatures up to about 540°C when subjected to long-term loading. (For higher thermal stresses: elevated-temperature steel, heat-resistant steel.) Typical applications: seamless steel pipes, boiler pipes.

high-vacuum sputtering

Panes of float glass have been finished with light-permeable, heat-reflecting coatings for many years. The high-vacuum sputtering method is now firmly established worldwide. The coatings consist of several layers of metals and metal oxides ranging in thickness from 0.1 to 0.01 nm.


A point at which the continuity of a building component is interrupted. Not all internal forces can be transferred across a hinge. We distinguish hinges according to their internal forces. Hinges are found at the nodes of building components or structures.

hinge reference line

An imaginary line to DIN 18268 which fixes the position of a door hinge. It is measured from the upper frame rebate. Only after the hinge reference lines have been determined exactly for the upper and lower hinges is it possible to assemble door leaf, door hinges and door frame.

hinge, pin

This type of joint cannot accommodate any bending forces. The cross-sectional area of the pin in a fork joint must be such that it can carry the loads without shearing. A hinge gives a beam a minimal rotational capacity.

hinged door

An incorrect term for a side-hung door. The door swings open in one direction only. The door leaf fits flush with the frame upon closing. Multiple locking to all sides is possible to improve security.


A sloping linear intersection between two roof surfaces that slope downwards from this line.

hipped roof

A hipped roof has sloping surfaces on the gable sides as well as the eaves sides.

history of glass

Glass is not a human invention, but rather a copy of a natural product. Natural glass is produced, for example, during volcanic eruptions, meteorite impacts and lightning strikes. Astronauts found natural glass on the Moon! Experts assume that minerals on the Moon were melted to form “glass spherules” during meteorite impacts.


The German Honorarordnung für Architekten und Ingenieure (HOAI, Official Scale of Fees for Services by Architects & Engineers). The latest edition was published on 30 April 2009.

hollow section

Hollow sections can also be rolled sections. There are three forms: square, rectangular and circular. One further distinguishing feature is whether the sections are seamless or welded. Hollow sections are frequently used for architectural reasons because they present a more harmonious appearance than open cross-sections.

honed edge

The entire surface at the edge has been finely ground. Honed edge surfaces have a matt appearance. Untreated areas and chips are not permissible.

Hooke’s law

This law established by Robert Hooke describes the material constant E (elastic modulus, modulus of elasticity) that is defined by the ratio of the stress in a body to the relative change in its length.

horticultural clear glass

Like horticultural sheet glass but with a lightly textured surface (rolled glass with good light-scattering properties).

horticultural sheet glass

A low-quality glass used for greenhouses and frames for horticultural purposes.

hot wide strip line

A production line for hot-rolled wide strip material. We distinguish between three forms: continuous hot-rolled strips (five or six roughing stands and six finishing stands) and semi-continuous hot-rolled strips.

hot-rolled strip steel

Flat products with a rectangular cross-section and a width much greater than their thickness, manufactured from unalloyed or alloyed semi-finished steel products. The strip is wound up into a coil immediately after passing through the finishing roll, or rather after pickling or continuous annealing, in such a way that the side surfaces of the coil are approximately in one plane.


An optically effective property of glass with a relatively high selective absorptance and non-diffuse light transmission. The view through appears coloured (coloured glass) but focused. See: obscured glass.


German abbreviation for high-strength connection (Hochfestverbindung). A standardised bolted connection in which additional fittings to prevent loosening are not required. The bolt is secured by introducing an appropriate preload. HV connections must always consist of bolt, nut and washers from one supplier.


High Strength Bolt


This describes the flow behaviour of fluids. Hydraulic elements are included in façades for controlling sunshades or for opening roof windows. Hydraulic systems can be used to generate enormous forces. Hydraulic jacks are used for prestressing cable structures.

hydrogel coating

Such a coating increases the fire resistance of fire-resistant glazing.

hydrogen (H)

Hydrogen can damage steel through hydrogen embrittlement. It can infiltrate the steel during production and also during surface treatments. Tempering measures can remove the hydrogen.

hydrogen embrittlement

A change in the ductility of metals, more specifically their brittleness, through the infiltration and inclusion of hydrogen in their metallic structure. Hydrogen embrittlement is a form of corrosion, the results of which are similar to material fatigue.

hydrophilic surface

Such a surface is based on the wetting behaviour of fluids (water) on the treated surface. On a hydrophilic surface the water spreads out to form a film of constant thickness that runs off the surface and leaves behind no significant amounts of dry residue (hydrophilic = attracts water).

hydrophobic surface

Such a surface is based on the wetting behaviour of fluids (water) on the treated surface. A hydrophobic surface repels the water; pearl-like droplets form which can roll off and take particles of dust and dirt with them (hydrophobic = repels water).


Perhaps the most common section used in structural steelwork. The designation stems from the cross-sectional form of this rolled section. The central part is the web, which joins together the two, usually thicker, flanges.


A hot-rolled steel section with narrower flanges than an H-section.

ice flower glass

This type of glass is made from sheet glass that is first sandblasted and then coated with hot bone glue. As it dries, the glue contracts and tears irregular fragments out of the glass surface to produce the irregular “frost” look.

imposed load

The varying or movable effects acting on building components, e.g. due to persons, furnishings and fittings, stored materials, machines or vehicles. The intensity of the imposed load has a stochastic character.


Impregnation is carried out with substances that do not a form a surface film but instead infiltrate the pores of a material without, however, closing these completely. The diffusion of water vapour must remain guaranteed. Stone and concrete surfaces represent typical applications.


This is a trade name for a screw with a hexagon socket head. The tool used for this screw is the well-known Allen or hex key.


Abbreviation for International Commercial Terms. These terms of business are a series of voluntary rules for the drafting of customary contract clauses in international trade. First and foremost, Incoterms are intended to regulate the supply of goods. The provisions specify which transport costs are to be borne by the buyer or seller and who bears the risks.


The melting of decoration or relief into a piece of glass.

indium oxide

This is a chemical compound of indium and oxygen. Indium oxide is mixed with the glass during production in order to give it a yellow to amber-orange colouring.

Individual Approval

An Individual Approval (ZiE, Zulassung im Einzelfall) is required in Germany when a component (e.g. a glass safety barrier) does not have a National Technical Approval (abZ, allgemeine bauaufsichtliche Zulassung). An Individual Approval is normally obtained by carrying out tests that are supervised by an independent body.

infill element

Infill elements are generally the panels filling the spaces between the posts and rails of a post-and-rail façade. Windows, fixed glazing or insulating panels are employed as infill elements, which are mostly attached on site.

infrared transmittance

Non-coloured glasses have a high light transmittance in the wavelength range 780–2800 nm (decreasing from 780 to 2800 nm). Soda-lime-silica glasses exhibit an absorption band at 2.85 m.

ingot casting

A discontinuous forming method in which the molten material is poured batch-wise into moulds where it then solidifies.


A substance used to reduce the effectiveness of chemical or physical processes, e.g. rust inhibitor, bacteria inhibitor, fire inhibitor.

insect screen

This is a barrier against persons, animals or foreign bodies. An insect screen normally has a peripheral frame. Metal is the material most often used for the screen, but wood, stone or plastic screens are also possible.

Inspection & Test Plan (ITP)

An ITP includes all the tests and inspections necessary for fabrication or assembly processes. The tests etc. are specified in standards, customer specifications or internal seele standards.

inspection certificate

In this document the manufacturer confirms the results of tests on the basis of non-specific tests.

insulating glass

Insulating glass is an assembly of two or three panes of glass that are kept a certain distance apart by using metal or plastic frames. At the edges the panes are interconnected by gastight inner and outer seals. The thermal insulation and hence the U-value of the glass (Ug-value) are much better than a single pane of glass.

insulating glass with fixings

A type of insulating glass with integral mechanical fixings which gives a façade a good appearance, as though the glazing had been fixed with adhesive.

insulating material

A material with a low thermal conductivity or soundproofing properties which is used in the building industry (sound insulation, thermal insulation).

insulation fixing

Available in various forms for attaching different types of insulating materials, also those used as a background for plaster or render (e.g. external thermal insulation composite systems), to concrete, stone, solid or perforated bricks and aerated concrete. In Germany no approval is required for such fixings up to a building height of 8 m (DIN 1102).

integral sunshade

A sunshade fitted in the cavity of an insulating glass unit. Horizontal louvres are the most popular form. The advantage of a sunshade in the cavity is that it does not require any cleaning. The disadvantage is the difficult maintenance should any be required.

integrated façade

This type of façade acts as a heat or cold sink. Hot or cold water flows through the façade sections.

interface drawings

These drawings are used to demarcate the products and services of one supplier from those of another, e.g. a previous trade. Interface drawings are particularly important in the initial quotation phase in order to illustrate the products and services on offer. As a rule, each relevant area is marked in a different colour.

interference coating

Metal coatings based on silver, e.g. for low E glasses.

interference phenomena

Due to the optimum surface parallelism of float glass panes, optical phenomena can occur under certain lighting conditions due to physical properties. These manifest themselves in the form of rainbow-like blemishes, lines and rings which change their position when pressure is applied to the pane.


In laminated glass this is the material that bonds the glass together permanently. PVB is used for laminated safety glass, casting resin for ordinary laminated glass.

intruder alarm system

This is an electronically operated system for the protection of persons and property. Intruder alarm systems can notify the police or security services automatically in the case of intruders being detected.

intruder resistance

A ball-drop test is used for classifying the penetration resistance of laminated safety glasses in the case of thrown objects. This test provides the chance of designing glass combinations that can achieve a high resistance to attacks with simple, blunt tools.

intruder resistance class WK

Class that must be assigned to a façade or door if it is to prevent unauthorised access. The classes range from WK1 (lowest) to WK6 (highest). The higher the class, the more involved is the design.

intumescent paint

This coating foams up when exposed to high temperatures and thus insulates an object requiring fire protection against the effects of flames and heat.

investment casting

This method is used to produce cast parts with maximum dimensional accuracy and the best surface finish. The advantage of the method is that the cast parts are generally ready to install or need only very little further machining. This method is particularly beneficial for complicated components.


Former designation for a German wide-flange I-beam with parallel flanges.


Designation for a German I-beam with parallel flanges of medium width.


The appearance of rainbow colours on the surface of glass (sometimes caused by partial corrosion of the surface). The effect can also be generated artificially by applying a coating.

iridescent glass

This is a transparent, colourless or coloured, shimmering glass.


Iron is a chemical element in the periodic table of elements with the symbol Fe (Latin: ferrum) and atomic number 26. Colloquially, the material cast iron is often referred to as iron, whereas the material steel is not thought of as iron at all, even though iron is the main constituent of steel. Iron tends to corrode in the presence of damp air, water and damp soil. See: rust.

iron (II) oxide

A chemical compound of iron and oxygen, one of the oxides of iron. This oxide normally has a non-stoichiometric structure, the composition of which is approximately Fe0.84O to Fe0.95O.

iron ore

A mixture of chemical compounds of iron and non-ferrous rocks (the so-called matrix). The chemical compounds of iron in iron ore are essentially iron oxides, i.e. compounds of iron and oxygen, or iron carbonates.

iron oxide

Iron forms bivalent and trivalent iron oxide in the presence of oxygen. Iron oxide is mixed with the glass during production to give it a blue-green or yellow colouring, depending on the valency.

iron-carbon phase diagram

This diagram is the basis for understanding the microstructures present at certain temperatures – or rather the microstructure changes that occur upon gradual heating or cooling – in steels and cast iron materials.

island (fracture pattern)

An isolated fragment of glass within a broken pane, i.e. no part of the fragment is adjacent to an edge. This effect often occurs with heat-strengthened glass.


The International Organisation for Standardisation is a network of national standards institutes which prepares international standards.


Abbreviation for International Organisation for Standardisation. ISO standards are intended to simplify collaboration in scientific, technical and industrial fields. The abbreviation ISO is the same in every country, in every language. ISO standards are published in English and French.

ISO 14001

The international environmental management standard ISO 14001 stipulates requirements to be satisfied by an environmental management system which are acknowledged worldwide.

ISO 9001

The quality management standard ISO 9001 is an international standard that formulates minimum stipulations that must be satisfied by the management of a company in order to attain a certain standard in the implementation of its quality management system. ISO 9001 can be used to verify a certain standard of quality with respect to third parties.

ISO accreditation/certification

This indicates whether a company has introduced a quality management system that has been certified by an independent body. ISO 9001 and ISO 14001 are well-known certification systems. ISO accreditation is often a prerequisite for submitting bids for public-sector projects.

isolating joint

This is a joint with a nominal thickness of zero between structures, individual parts of a building or individual phases of a construction project.


Isotherms are lines connecting points with the same temperature. They are used in the graphic evaluation of temperature studies in building physics, to establish whether the chosen form of construction satisfies the building physics requirements. Isotherms are usually calculated with the help of special software.


Information technology – a collective term for the acquisition and processing of data by computer


Abbreviation for information technology. The IT department is responsible for providing and maintaining (system administration/supervision) the necessary computer infrastructure (hardware, software, network).

jib, boom

That part of a crane that projects beyond its supports.

joint permeability

This describes the rate of airflow via the joint between opening light and window frame. It is expressed by the joint permeability coefficient a², which describes how many cubic metres of air pass through one linear metre of joint in one hour for a pressure difference of 10 Pa.

joint permeability coefficient

The joint permeability coefficient (a-value) specifies how much air (in m³) per metre length of joint passes through a window per hour with a pressure difference of 1 kp/m². The smaller the a-value, the tighter the window closes, the lower the heat losses and the better the sound insulation.

joint sizing

The size of the joint between window frame and adjacent building component must be such that all components meeting at this point can expand, contract and move without hindrance. At the same time, the joint must still remain weathertight and watertight.


Sealing materials (e.g. silicone) or sealing products (e.g. tapes, waterstops, precompressed foam profiles) are fitted into joints to prevent the ingress of water.

Jominy specimen

A sample of material for determining the hardenability in the end quench test according to W. E. Jominy (DIN 50191). The specimen is 100 mm long and 25 mm in diameter.

k-Wert (k-value)

Obsolete German expression for thermal transmittance. See: U-value.

KG – edge cut

Designation for a cut glass edge without edge working. The typical wavy lines of the cutting tool are still visible and there may be undercut or overcut. Such a cut edge is extremely sharp: risk of injury!

KGN – edge ground

Designation for edge working to DIN1249 in which the entire edge of the glass is processed. The edge has a matt ground appearance, the arrisses are chamfered.

KGS – edge arrissed

A form of edge working to DIN 1249. It designates a cut glass edge, the arrisses of which have been swiped with a grinding tool.

killed steel

Steel cast with deoxidising agents (Si, Mn, Al) or following vacuum treatment. Owing to the addition of the deoxidants, it solidifies in the mould without boiling, without spraying sparks.

KPO – edge polished

Designation for a ground straight edge that is polished to improve the quality of the surface. Polishing marks that can be seen and felt are permissible, but there should be no matt areas.


A colourless, odourless noble gas that does not form chemical compounds with any other substances. When used in the cavity of double glazing, it can reduce the U-value of the panes by approx. 0.4 W/m²K. The low thermal conductivity of krypton enables the width of the cavity to be reduced.

ladder element

A frame structure that is delivered to the building site prefabricated and only has to be integrated into the façade. This enables large façades to be erected in a very short time.

lamellar tearing

A specific failure scenario in the loading of steel plates in tension in the direction of their thickness. A weakening of the material caused by thermal contraction strains during welding, which can be avoided by designing properly to suit welding techniques. Certain grades of steel are more resistant to lamellar tearing.

laminated glass

This type of glass consists of two or more glass plies bonded together with one or more interlayers, e.g. casting resin or a highly tear-resistant, viscoplastic, thermoplastic sheet.

laser beam welding

This method of welding is primarily used for welding components that must be connected fast, need a narrow, slender weld seam and can accommodate only minimal thermal distortion. This type of welding is usually carried out without the need for a weld metal.


Latticino is a type of reticulated glass in which milky white glass threads are melted onto clear glass.

lead crystal

A clear, high-quality glass containing lead which is characterised, in particular, by its splendid shine.

lead crystal glass

This type of glass exhibits especially high light refraction, which is advantageous for the decoration and faceting. It is therefore very popular for drinking glasses, vases, dishes and chandeliers.


The addition of a covering of lead to a steel surface to protect against corrosion. The workpiece is immersed in a bath of molten tin or coated by an electrolytic process.

leaded lights

This special glazing method is based on the principle of framing small coloured, painted or etched (sandblasted) panes of glass with soldered lead bars (so-called cames) to form a complete pane which is subsequently mounted in a door or window.


Leadership in Energy and Environmental Design (LEED) was developed in 1998 by the US Green Building Council in order to create a system for classifying ecological construction. The system awards points for various environmentally friendly characteristics of a building. The higher the number of points awarded, the higher is the LEED certification.


A narrow, marginally projecting vertical feature (functional or decorative) on a wall or façade.


The height of a point on a structure above sea level or the reference level of the structure and expressed in a uniform system. Levels above the reference point are indicated by a plus sign, those below by a minus sign. On drawings, levels are indicated by a triangle symbol, solid for structural levels, outline only for finished levels.


The surveying, i.e. measuring, of the difference in height between two points.

levelling compound

A material used for levelling any unevenness in a floor. Self-levelling compounds spread out to form flat, level surfaces following a rough distribution.

lift glazing

The glazing to lift enclosures or cars consists mainly of safety glass. Despite the presence of this safety barrier, the usual regulations for glazing preventing falls do not apply here.

lift-and-slide door

With this type of door the horizontally sliding leaf is lowered into its weathertight position upon being closed. The opening mechanism first lifts the sliding leaf out of its floor seals and then slides it to the side on rollers.

lift-off protection

A precaution necessary for suspended components (e.g. sheet metal elements) that prevents them being lifted off by persons or the wind. This can be, for example, simply a screw positioned at a suitable point.

lifting eye bolt

A ring with a stud on one part of the ring, the thread of which points away from the centre of the ring. It can be screwed into a female thread provided in a heavy component (e.g. façade element) for lifting purposes.

lifting eye nut

A ring with a nut formed in one part of the ring, the thread of which points towards the centre of the ring.

light (re)directing system

Such systems (re)direct daylight in a controlled way into interior areas deeper within the building, which means that the use of daylight and the interior illumination can be optimised. A light (re)directing system should help to reduce the amount of artificial lighting required.

light absorption

This is the designation for a physical interaction in which the light transfers its energy to a material. Light absorption is a special case of the more general physical phenomenon of absorption.

light shelf

This is a component that optimises the use of daylight by redirecting it further into the interior. Light shelves introduce a distinctive horizontal segmentation into a façade. They are particularly worthwhile in conjunction with double-leaf façades.

light transmittance

The light transmittance of a glazing unit is the percentage of solar radiation in the visible range of wavelengths (approx. 380–780 nm) that passes through the glazing.

light transmittance

The light transmittance of a single pane of glass for the visible range of the spectrum is approx. 82 %. Insulating glass has a light transmittance of < 80 % in this range.

light-diffusing glazing

A glazing unit with at least two panes of glass and a glass-fibre mat or glass fleece in the cavity.

light-emitting diode (LED)

This is an electronic semiconductor component. When a current flows through the diode in the forward direction, it emits light.

lightweight concrete

Concrete with a density not exceeding 2.0 kg/dm³. Lightweight concrete is a mix of cement, aggregates and water. The aggregates used include pumice, expanded clay, foamed slag, expanded shale, etc.

lightweight construction

A form of construction in which one of the priorities is to save as much weight as possible. One main reason for lightweight construction is the saving of raw materials in the manufacture and usage of products.

limit of size

This specifies the amount by which a certain dimension may deviate. For example, the thickness of float glass may deviate by 0.2–1.0 mm from its nominal thickness (depending on the thickness).


A lintel is a horizontal beam, usually made from timber, masonry, steel or reinforced concrete, over an opening in a wall such as a door or window. A lintel carries the loads from the section of wall directly above it and transfers these to the wall sections either side of the opening.

liquid penetrant test

A test used to establish defects that are open to the surface of a material. All materials that are compatible with the test liquid and not too porous may be tested using this method. The test is used for checking weld seams, cast parts, etc.

liquid penetrant test

A test used to establish defects that are open to the surface of a material. All materials that are compatible with the test liquid and not too porous may be tested using this method. The test is used for checking weld seams, cast parts, etc.

load-carrying capacity

Generally, this specifies the maximum load a building component can carry.

location block

Location blocks prevent movement of the pane of glass within its frame. They are intended to direct forces acting on the glass to the loadbearing construction. In addition, they prevent contact between the edges of the glass and parts of the construction such as bolts, screws, etc.


A lock holds a door or window closed and prevents unauthorised entry. Locks are designated according to the position of the hinges: hinges on left side = DIN left; hinges on right side = DIN right.

long-term supply agreement

This contract for goods with a preferred original condition is a declaration in which the supplier provides details about the original condition of the goods supplied and for which countries customs duties reductions apply according to the applicable free trade agreement.

lotus effect

A surface with the lotus effect has a water-repellent (hydrophobic) coating with a microstructure similar to that of the surface of the leaves of the lotus plant. This structure prevents the water spreading and instead round droplets form.

louvre blind

An active sunshade mounted externally.

louvre blind in insulating glass

This is technically no longer a problem. The main applications are privacy screens between offices, between operating theatres, and places where normal louvre blinds cannot be fitted.

louvre façade

In architecture and construction this is a façade design in which louvres are installed over a large area. The louvres can be made from a wide variety of materials, but wood, metal and glass are common choices.

low E glass

Abbreviation for low-emissivity glass. The low emissivity is achieved with an ultra-thin metallic coating that considerably reduces the radiation losses from the glass surface.

low emissivity/low E glass

A low E glass is an insulating unit in which the inside face of the inner pane (i.e. in the cavity) is coated with an ultra-thin layer of a noble metal (selective layer) which considerably reduces the loss of energy. The most important criteria for assessing a low E glass is the total energy transmittance (g-value) and the thermal transmittance of the glass (Ug).

low-iron glass

Glass for applications where optical properties are relevant. Low-iron glass is suitable for façade and internal glazing where a high degree of transparency is desired. Eliminating iron oxides from the glass melt considerably reduces the typical, slightly greenish tint of glass. Well-known trade names: “Optiwhite”, “Diamant”.

lower chord

The bottommost member in a trussed girder. In single-span girders the lower chord is loaded only in tension. A very slender member is therefore possible because it does not have to satisfy stability criteria.

lump sum price

The remuneration agreed for carrying out certain construction or other works without verification of the exact quantities used in the individual measures performed. Such a price can be agreed for an entire structure, but also just for a group of individual works specified in the contract.

lustre colour

Lustre colours are applied to the surface of the glass with a brush and fired in a reduced-oxygen atmosphere. Lustre colours are less durable than reduction colours.


A macrosection examination is carried out by grinding the workpiece specimen to a fine finish and then applying an etching solution to the surface. This reveals coarse structures, e.g. number and arrangement of weld runs in a weld seam, also defects, hardness zones in case-hardened parts or cast structures.

MAG welding

Metal active gas welding is a process in which an electric arc burns within a protective shield formed by active, incombustible gases. The electrode is fed from a reel; the torch can be guided manually or fully automatically by a welding robot. This type of welding is used for unalloyed steels.

magnetic particle test (MT)

A test used to establish defects on or near the surface of magnetic materials, primarily ferritic steel and ferritic iron.

magnetic welding clamp

This is used to hold two metal pieces at a certain angle so that they can be welded together, for example.


This is an iron ore with a high iron content. The iron and oxygen atoms are firmly bonded together in magnetite.

management accounting

This is a control and coordination concept that supports the management and accountable positions during the targeted influencing of existing operational processes. The task is to monitor the economic efficiency in the company on behalf of the management but not to guarantee this.

management of extras/additional work

This is the monitoring and assessment of deviations and changes and their economic consequences for the purpose of determining and asserting claims. In project business this element is found on both the contractual and client sides.


A chemical element that has been used in the production of glass since ancient times. Manganese can be used to increase the strength and toughness of a material.

manganese oxide

This is a chemical compound of manganese and oxygen. During the production of glass manganese oxide is used to remove the yellow-green tinge caused by small quantities of iron silicates in the raw materials.

mansard roof

A pitched roof form with two different pitches on each side and the lower surfaces at a much steeper angle than the upper ones. This form allows the roof space to be better used. (US: gambrel roof)


A ferromagnetic metastable structure in metals which is formed from the original microstructure by a cooperative diffusionless, athermal, shear transformation.

mast-climbing platform

A type of access platform of variable width for transporting persons and materials up to and also working at heights of about max. 60 m.


A special type of rolled glass with small embossed squares.


A special type of rolled glass with embossed longitudinal grooves.


A special type of rolled glass with small embossed elongated rectangles.

material fatigue

Material fatigue is the slow progression of a damaging process in a material exposed to environmental influences such as alternating mechanical loads, fluctuating temperatures, possibly the effect of a corrosive medium as well.

mechanical ventilation

In this type of ventilation motor-driven fans with thermal cut-outs control the removal of excess heat. They draw the warm air to the highest point and then expel it. Cooler air enters at the base to replace this. Mesh screens over the inlets and outlets prevent the entry of insects and small animals.


This is a separating layer. We distinguish between impermeable, semi-permeable (or selectively permeable) membranes, and those that are permeable in one direction only (unidirectional) or in all directions (omnipermeable).

membrane technology

A technology employed for thin, lightweight plate and shell structures. The theory is based on the assumption that bending must be ruled out in such a thin structure because it causes unacceptable deformations. The structure can accommodate only shear stresses and direct tension or compression. In the case of a shell loaded in compression, or a tent structure loaded exclusively in tension, bending is eliminated by designing a suitable perimeter construction. These – in relation to their surface area – very thin membranes avoid such stresses by deforming or by dissipating any induced prestress.

metal expansion anchor

This anchor benefits from a clamping or wedging effect that holds it in the drilled hole. This effect is achieved by driving a cone into an expanding sleeve, which forces the parts of the sleeve apart to make contact with the sides of the hole. Metal anchors have a higher load-carrying capacity and are more secure than those made from plastic because they can transfer considerably higher expansion forces to the sides of the hole and hence the material of the wall.

metal halide lamp

This type of lamp with a halogen filling belongs to the group of discharge lamps. The primary applications are the illumination of goods (“shopping light”), trade fair halls, building floodlighting, stadiums, production buildings and warehouses.

metal louvre system

Louvres can be used to influence the distribution of light and shade within a building. Metal louvres allow the amount of daylight entering the interior to be regulated.

metal sandwich panel

A three-ply composite panel with vibration-attenuating properties.

micro-alloyed steel

This is an unalloyed tempering steel type in which the quantities of, for example, vanadium and/or niobium or titanium added lie below the limiting values for alloyed steels.


Multi-pane insulating glass, which consists of at least two panes of glass that are separated by at least one cavity formed by the spacer.

MIG welding

Abbreviation for metal inert gas welding.

MIGUTRANS expansion joint profile

An aluminium cover strip with perforated and serrated fixing legs and an elastic seal made from synthetic rubber.

mill scale

A residue or layer of oxide that forms on the surface of steel during annealing, rolling or forging. Mill scale consists of several layers of oxide with different chemical compositions.

mill train, rolling train

A production line consisting of one or more roll stands and all the associated feeding, handling and cutting plant.


This metalworking process is used to produce flat surfaces or contours. The milling cutter exits the workpiece and the cooling after every revolution and the cutting action of the cutting teeth. This intermittent cutting action leads to fluctuating cutting forces and temperatures at the cutting teeth.

mineral fibres

These are inorganic fibres with a natural or artificial origin. Mineral fibres can frequently be used for textile applications, e.g. for mineral wool or for weaving asbestos.

mineral glass

This term is frequently used for watch crystals in order to differentiate ordinary glass from the much softer synthetic glass materials and the very much harder synthetic sapphire.

mineral wool

This is an incombustible insulating material made from either glass wool or rock wool.


A small mobile crane for internal and external deployment with non-damaging outriggers and rubber tracks. Such cranes are used on muddy ground, steep slopes and wherever space is tight (e.g. in interiors) or where a low plant weight (e.g. on marble floors) is essential.


This is a surface that reflects light and therefore shows an image of anything in front of the mirror. A reflection in a flat mirror reproduces both lengths and angles accurately, but the image is handed, i.e. left and right are reversed. Traditional mirrors are these days made from sheet glass coated with aluminium.

mitre bevel

A type of edge working used on glass and mirrors, especially thick materials.

mitred corner

The two parts to be joined at the corner are cut at an angle.

mitred glass edge

A glass edge sloped at the appropriate angle. Mitres can be honed or polished.

modified sine wave

This output wave form simulates a sine wave and consists of a flat plateau of positive voltage which drops abruptly to zero briefly, then drops again to a flat plateau of negative voltage, then back to zero briefly before returning to the positive voltage. It is sometimes erroneously called a square wave.

modular design

The division of a whole unit into regular parts known as modules.

Moiré effect

An optical phenomenon that can occur in the form of a wavy, rippled or circular pattern under certain lighting conditions. The Moiré effect can also occur when patterned panes of glass are laid on top of each other and the patterns are not concurrent.

moisture control

The important aspects in moisture control are to protect the window against the infiltration of rain from the outside and to prevent condensation on the inside and at the junctions with the adjoining components.

moisture transport

Considerable quantities of water vapour are transported in air flowing from warm to cold zones as well as by way of diffusion. This is particularly noticeable at joints and gaps, where water can collect at the colder places.

molecular sieve

This is a desiccant used in the spacers of insulating glass which ensures dehumidification of the cavity between the panes. A molecular sieve has a limited moisture absorption capacity and so the lifetime of an insulating glass unit is finite. Also known as drying agent.


A chemical element. A molybdenum content of 0.2% improves the through-hardening of steels and at the same time prevents temper embrittlement. Owing to its microstructure-stabilising effect at high temperatures, molybdenum is used in materials designed for high operating temperatures.


Single homogeneous pane configuration (in contrast to a composite pane configuration such as laminated safety glass).

monopitch roof

A roof form with only one sloping surface. The lower edge is the eaves, the upper edge the ridge. Also known as lean-to roof.

motif glass

This type of glass is produced by passing the glass mass between two rollers while it is still fluid. These emboss a high-precision geometrical or other motif in the glass.


One application of a moulding is to separate various levels or transitions between materials, e.g. junction between floor and wall, soffit and wall.

movement joint

In buildings and structures a movement joint is a gap between two components or materials. The purpose of a movement joint is to interrupt components and therefore prevent stress-induced cracking.

mpact sound insulation

An insulating material used to attenuate the noise of footsteps. In Germany impact sound insulation requirements are regulated by DIN 4109 “Sound insulation in buildings”.

MS polymer

A silicone-free synthetic material that can guarantee a hydrophilic function for the entire glass surface right up to the sealed joint. MS polymers consist of polypropylene oxide with silane end-groups.

multi-bay ventilation

In this type of construction several bays of the façade, one above the other, are not separated by seals but instead the post and rails are interconnected via open rebates at the sides. Any water that collects drains from the rails to the posts and to the outside at the base of each post.

multi-function insulating glass

This type of glass complies with thermal insulation, sound insulation and also anti-intruder requirements.

multi-pane insulating glass

This is a type of insulating glass that consists of two or three panes. There is a hermetically sealed cavity between each pair of panes which is filled with a noble gas such as argon or krypton.

multi-ply safety glass

Term occasionally used for laminated safety glass.


Nanotechnology is the study of materials on the atomic or molecular level. The dimensions of nanoparticles lie between those of an atom and a beam of light. Today, the chemical production of nanomaterials (Lotus effect coatings) is included in the term nanotechnology.

natural colour

All the materials used in glass products have their own natural colours, which can become more noticeable as the thickness of the glass increases. Fluctuations in the colouring are the result of the differing iron oxide content in the glass, the coating process, the coating and changes in the glass thickness and the make-up of the pane.

natural glasses

The natural types of glass are the result of the melting of sands. Obsidian and pumice have volcanic origins, impactites and tektites stem from meteorite impacts and fulgurites are caused by lightning strikes. Of course, seele uses only man-made varieties of glass for constructing façades and roofs of glass which look entirely natural.


Abbreviation for Natural Color System®, a colour model based on the way an observer perceives a colour. NCS notation is made up of blackness, chromaticness and hue components. This colour system permits much finer gradations of colouring than, for example, the RAL colour chart. To date some 1950 hues have been categorised.

network modifier

This is a compound that together with one or more network formers creates a glass material by altering the microstructure and properties of the glass.


Nickel is a metal and in conjunction with chromium the principal alloying element in corrosion-resistant austenitic steels. Nickel is especially useful in the hardening and tempering of large cross-sections because it enables high strength and optimum toughness values to be achieved.

nickel oxide

Nickel forms inter alia bivalent nickel oxide in the presence of oxygen. Nickel oxide is mixed with the glass during production to give it a violet or reddish colouring.

nickel sulphide failure

The failure of a pane of toughened safety glass due to the expansion of nickel sulphide inclusions.

nickel sulphide inclusions

Very small, almost spherical impurities in glass. Under certain circumstances they can cause spontaneous failure of toughened safety glass panes.


A chemical method for hardening the surface of steel with the help of nitrogen. The surface can achieve a heat resistance of up to 500°C. The subsequent oxidation results in corrosion protection. Nitrided components are used, for example, in highly stressed bearings with slip planes in cable-net façades.


See: nitriding.


Nitrogen is a colourless, odourless and tasteless gas. It is a chemical element with the symbol N and atomic number 7. In materials engineering liquid nitrogen is used to eliminate austenite from hardened steels.


This is the point in a structure at which several components meet. The term node is frequently used in conjunction with the intersection of linear steel components. From the structural engineering viewpoint, any chosen point in a structure or component can be regarded as a node.

noise barrier

A noise barrier of glass is used to attenuate noise originating from a linear or planar source so that at the place to be protected the noise is weakened to such an extent that the limit value specified in the relevant legislation is complied with.

noise floor

This is the minimum sound level, and perceived as “quiet”, measured at a location at a certain time:

nominal diameter (DN)

The inside diameter of a pipe or a pipe fitting such as a valve.

nominal size

Nominal sizes are theoretical figures that specify the mathematically exact distance between two measurement or reference points. See: actual size.

non-ferrous heavy metal

This term is used exclusively for heavy metals based on copper.

non-ferrous metals

This is the collective term covering all pure metals (apart from iron) and all metal alloys whose main constituent is not iron. We categorise them according to their density: light metals (< 5 g/cm²) and heavy metals (> 5 g/cm²).

non-positive connection

This type of connection is produced by the application of a force generated by a suitable prestress or preload. The connection between the parts is maintained purely by an adhesive force. The forces to be transferred act tangentially to the mating faces of the parts.

non-shrink grout

This is used for casting steel components into concrete, for filling joints between prefabricated components and concrete, and for closing off openings and joints in concrete. A space must be left for the grout between the steel and the concrete. Air in this space must be able to escape. This grout does not shrink once it has cured.


German abbreviation for natural smoke and heat vent (natürliches Rauch- und Wärmeabzugs-Gerät). Such vents dissipate hot gases and fumes in the event of a fire in order to create smoke-free zones at floor level and in escape routes. DIN EN 12101-2 specifies the design and use of these vents.

obscured glass

An obscured glass product that scatters the light diffusely. Obscured glass is produced by roughening the surface either mechanically (sand-blasting) or chemically (acid-etching). Also known as frosted glass.


A glass surface treatment involving acid-etching, sandblasting or grinding.


This is a naturally occurring form of glass, black in colour.

obstruction notice

Notification to the client of a disruption on the building site that a contract or part thereof cannot be performed as contractually agreed The obstruction notice has informative, warning and protective functions.

occupational safety

This is a generic term covering all measures intended to improve safety at work. Safety is an essential prerequisite for performing any type of work. Occupational safety takes into account the technical, organisational and labour requirements of the work in order to guarantee safe working. Any work that cannot be carried out safely represents a health risk.

ogee arch

This type of arch is made up of arcs curving in opposite directions, one convex and one concave on each side.

OHSAS 18001

Abbreviation for Occupational Health & Safety Assessment Series, a specification that can be used by all types of companies, all sectors of industry. It represents a certification system for health and safety at work which has been defined by international certification organisations. It can be integrated into ISO 14001 or ISO 9001.


Österreichisches Institut für Bautechnik (Austrian Institute of Building Technology). The organisation to contact for issuing European Technical Approvals and the accreditation of testing laboratories, inspection bodies and certification bodies in Austria. The Austrian equivalent of Germany’s DIBt.

one-way vision glass

Mirrored glass that appears transparent when viewed from the brighter side towards the darker side.


Opacity is a measure of the light impermeability of a substance. The transmittance of an opaque material is zero.


The ability of material to prevent the passage of light, to prevent a view through. The opposite of transparency.

opal glass

An opaque glass to which fluoride compounds have been added.

opalescent glass

This is a composite glass pane made from materials from various glass melts. It can be colourless or contain coloured components.

opalising glass element

Such a glass element creates a shimmering, glittering effect in sunlight.

open-grid flooring

A self-supporting, loadbearing (e.g. for foot or vehicular traffic) plate-type construction with regularly spaced apertures. This type of floor is used for platforms, walkways, stairs, landings, steps, etc. It generally consists of loadbearing, transverse and perimeter bars.

optical glass

Lenses, prisms and mirrors for optical systems, e.g. objectives or telescopes, are produced from optical glass. In principle, there is no real difference between normal glass for windows and optical glass.

order picking

This is the making-up of a order for certain smaller quantities or numbers of goods obtained from a larger quantity or number (the range). The order can originate from a customer or from a production department.

ordinary low-carbon steel

Steel grade with a quality specification that does not require any particular measures during production.

organisation chart

A graphic representation of the hierarchical structure of an organisation, e.g. an authority or a company. It contains, for example, the arrangement of the personnel allocation and should be aligned with the organisational procedures.

original calculation

The original calculation is the sealed version of a priced quotation handed over to the client. In terms of content, the original calculation corresponds to the documentation of the calculation with the assumptions that form the basis of the quotation and, consequently, any contract that may be awarded.

ormal force, axial force

A normal force acts in the direction of the longitudinal axis of a member, i.e. perpendicular to the cross-section. A normal compressive force compresses the member, a normal tensile force stretches it. A normal force causes axial stresses in the cross-section. At a sufficiently large distance from the point of application of the force, the distribution of the stress can be assumed to be constant.


The abbreviation for oriented strand board, a wood-based panel product produced from long, slender wood chippings. OSB products are mainly used for internal applications.

Österreichisches Normungsinstitut (ON)

The Austrian Standards Institute (ASI) is a not-for-profit, impartial organisation for producing standards. It drafts ÖNORM and ON standards on the basis of Austria’s Normengesetz (standardisation law). The institute was originally founded under the name of the Österreichischer Normenausschuss für Industrie und Gewerbe (Austrian standards committee for trade and industry).


German abbreviation for overhead door closer (Obertürschließer).


Österreichischer Verband für Elektrotechnik (Austrian Electrotechnical Association)

overhead glazing

Glazing with an inclination of more than 10° from a vertical line which has continuous linear supports on at least two opposite sides. The use of overhead glazing is dealt with in the German Technische Regeln für die Verwendung von linienförmig gelagerten Verglasungen (TRLV, Technical Rules for the use of Glazing on Linear Supports).


Overheads are calculated as a percentage of sales/turnover and are added to the calculation.


Österreichische Vereinigung für Qualitätssicherung (Austrian Association for Quality Assurance)

packing list

A table containing all the parts to be dispatched in one delivery.

panic bar

A panic bar enables a door to be opened easily in an emergency because it spans the full width of the door. Such door hardware is particularly important where a large number of escaping persons is to be expected.

panic lock

This is a type of lock used on doors in escape routes. From the outside the door can only be opened with the appropriate key, but from the inside the door can be opened without a key. A panic lock must comply with building legislation.

parallel detailed design

Elaboration of one detail on two drawings in parallel.


A parapet is a solid wall (usually of concrete or masonry) that rises above the edge of a roof or bridge deck.


A low perimeter wall above roof level that conceals the edge of the roof.


This is the natural or artificial development of a non-metallic protective layer on a metallic material which prevents or significantly slows down the corrosion of the underlying material. One example is stainless steel: the chromium in the steel forms a layer of chromium oxide that prevents further oxidation.

patent glazing wing/cap

This component forms part of a patent glazing system and presses the pane of glass against the supporting framework – mostly a post-and-rail construction. Patent glazing systems can result in visible frame widths < 50 mm. Aluminium sections are favoured for such components, but plastic or steel sections are also used.


A surface characteristic caused by a natural or artificial ageing process.

pattern charge

See: shape charge.

pavilion roof

Roof form with at least three surfaces that slope inwards to a point. Roofs on towers sometimes have this form.

PDM for CAD systems

Product data management (PDM) for computer-aided design (CAD) is a system that manages and backs up data and documents so that they can be made available at later phases of the product life cycle. In order to guarantee cooperation across the seele Group irrespective of location and organisation, a PDM system has been implemented for CAD/CAM procedures.


A two-phase, lamellar structural component in steel. (Not to be confused with “perlite”, an amorphous volcanic glass.)

peel test

This is a suitability test for structural glazing silicone which can be carried out on a flat test surface (pane of glass or sheet metal).

PEN conductor

Abbreviation for protective earth neutral conductor. In electrical engineering this is a conductor that performs the functions of the protective earth (PE) and the neutral (N) conductors simultaneously. A conductor with such a dual function is only possible in a TN network.

pendulum impact test

This is a test setup for investigating the strength of laminated safety glass and glazed safety barriers. Pendulum impact tests are carried out with a soft impact body according to a Euronorm.

per diem

See: expenses allowance.

perforated plate

A flat metal product with identical openings (perforations) at a constant spacing. The perforations can be produced by punching, drilling, milling or other methods.


A regular pattern of small holes in hollow bodies or flat products. The size, spacing and shape of the perforations depend on either technical or aesthetic requirements.

perimeter/edge cable

The function of this wire rope is to transfer the load from a membrane surface to the respective corner points. The membrane, generally made from polyvinyl chloride (PVC) or polytetrafluoroethylene (PTFE), is provided with a pocket along the edge for housing the cable.


This is the process in which a medium infiltrates or penetrates a solid.

perspective projection

The representation of three-dimensional objects on a two-dimensional plane to give a three-dimensional impression.


The photocatalytic layer decomposes organic particles lying on the surface of the glass. The decomposition process takes place continuously as long as daylight is available, and the layer is as durable as the glass product itself. The coating consists of titanium dioxide.


This is the name given to the direct conversion of solar energy into electrical energy by means of solar cells. The photovoltaic effect is based on the fact that sunlight generates an electrical voltage in a semiconductor material which can then be drawn off in the form of an electric current.

physical decolourisation

This process makes use of complementary colours. These mix with the existing colours to produce white. However, one serious disadvantage of this method is that the light absorption increases due to the presence of several colorific oxides and the glass appears darker. Another method of decolourising is chemical decolourisation.

Piab LKVE overload protection

This instrument is an electronic force sensor that can be mounted directly on a permanently installed cable. It is intended to protect against overloads, secure non-preloaded cables, indicate loads and the total of several lifting procedures.

Piab RTM 20 D wire tension meter

This instrument includes a microprocessor for the accurate determination of the force in a loaded cable or wire, e.g. guy ropes, contact wires, suspension cables. It is placed directly on the wire and the tensile force is shown immediately in the display.


A method for removing unwanted layers of oxide from a metal surface prior to a coating process.

pig iron

An intermediate product in steelmaking. It is characterised by its high carbon content of 4.0–4.7% and tramp elements such as phosphorus, sulphur, silicon and manganese.

pigeon control

A pest control expression that covers all methods (e.g. nets, spikes) of scaring off damaging birds or preventing them from landing or nesting.


In architecture a vertical column that also has a space-enclosing function.


This is a cylindrical element for creating an articulated joint between workpieces. In this type of connection the pin is generally loaded not in tension, but primarily in shear. Pins can be held in position by a screw thread or a split pin.

pinned connection

This type of connection is produced by inserting an oversize pin through all the parts to be connected. Pinned connections can perform three functions: locating, fixing and overload protection. A huge variety of standardised pins are available for these different functions. The most common pin types are: dowel, tapered, grooved and slotted spring.

pipe nut

A component (to DIN 431) for connecting pipes with a screw thread.

pipe, tube

A hollow element, usually with a circular cross-section, the length of which is normally much greater than its width.

pitch (of stairs)

Different types of stairs have different pitches. The pitch depends on the depth of the tread and the height of the riser. To be able to use the stairs comfortably, the most favourable pitch is achieved with a tread depth of 290 mm and a rise height of 170 mm (= 30°).

pitched roof

A sloping roof with a minimum roof pitch of 22 or 30° (depending on the particular building regulations).

pitting corrosion

Stainless steels in contact with active media containing chloride ions, e.g. seawater, can suffer from this type of corrosion with its distinctive needle-like notches in the surface of the material. This type of corrosion is very dangerous in the case of pressurised pipes and vessels.

Pittsburgh process

This drawn glass process has been used since 1928. It represents a combination of the Fourcault and Colburn processes and the intention is to exploit the advantages of both processes. The Pittsburgh process, which was invented by the Plate Glass Company, resulted in a considerable improvement in productivity.

plan drawing

A (normally) scale representation of a horizontal surface in a building, usually a floor with the walls shown in horizontal section. The plan also provides information about the functions of the individual rooms/areas. The building documentation must include plan drawings of all floors.

plasma arc welding (PAW)

A welding process that uses a plasma arc as a heat source. It is used in precision welding and microwelding (0.1–0.5 mm sheet metal), but also increasingly for thicker sheets and tubes made from alloyed steels and non-ferrous refractory metals.

plasticiser migration

This is an interaction in which the essential material properties are modified to such an extent that the function of the system is permanently altered or impaired.


These are man-made, organic materials. They are produced through chemical conversion (a process called synthesis), mainly from petroleum, natural gas and coal, but also other raw materials.

platform-frame construction

One of the main timber construction systems, closely related to panel construction. The difference between the two is that in platform-frame construction the components are supplied partially prefabricated for subsequent assembly on site to form a stable structure.

point fixing

Glass fixing for holding panes of glass in position at a discrete point.

point-fixed glass façade

Avoiding the use of frames and using point fixings instead results in an unrivalled degree of transparency. In Germany point-fixed glass façades require an Individual Approval because they are not classed as regulated construction products.


A device for measuring the surface tension in glass. After determining the bath side, the measuring point is wetted with an indicator fluid. The device, which works with a laser beam, enables the compressive stress in the surface to be measured exactly.

polyalkylene terephthalate

This is a plastic with a hardness and wearing resistance similar to that of polyoxymethylene, but only suitable for applications < 70°C. It is used for bearings in precision mechanics, for guiding and sliding bushes and for underwater installations.

polyamide anchor

A component that is used for fixing a screw or object to masonry or concrete. The commonest form is the anchor made from polyamide, a thermoplastic.


These are transparent, colourless synthetic materials with high impact resistance and stiffness. In the building sector polycarbonates are used as an alternative to glass.

polyethylene (PE)

This is a thermoplastic. It is resistant to water, low temperatures and mechanical abrasion. Suitable for high but brief impact loads.

polyimide (PI)

This is a thermosetting plastic that is very hard and very resistant to wear. Polyimide exhibits a high friction coefficient in dry running situations at temperatures < 70°C.

polyisobutylene (PIB)

This is a thermoplastic sealant used in insulating glass units as the primary seal between the hermetic edge seal and the glass.

polymethyl methacrylate (PMMA)

This is a synthetic, glass-like thermoplastic material often colloquially referred to as Perspex or Plexiglass, i.e. acrylic sheet.

polyoxymethylene (POM)

This is a high-molecular thermoplastic. Compared with polyamide, it is harder and can accept a higher compressive load, but is more sensitive to impact. It is suitable for dry running or when there is a lack of lubricant, and is used for bearings in precision mechanics.

polystyrene (PS)

This is a transparent, amorphous or semi-crystalline thermoplastic. Amorphous polystyrene is widely used, either as a thermoplastically processed material or as a foam (expanded polystyrene).

polysulphide polymer

This is a permanently elastic sealant that is used in insulating glass units as the secondary seal for filling the outer hermetic edge seal.


Inorganic polysulphides are the salts of hydrogen polysulphides. Polysulphides are used to produce sealing compounds for the building industry and insulating glass applications. The hermetic edge seal of an insulating glass unit is often sealed with a polysulphide (secondary seal). The best-known trade name for a polysulphide is Thiokol®. Thiokol® is not UV-resistant and therefore the edge seal must be shielded from the light.

polytetrafluoroethylene (PTFE)

This is a semi-crystalline polymer of fluorine and carbon. It is not sensitive to soiling, the action of oxygen, ozone or UV radiation and is classified as incombustible (DIN 4102 class A2).

polyvinyl butyral (PVB)

This is a synthetic material primarily used as a hot-melt adhesive in the form of an intermediate sheet (interlayer) for laminated glass. The standard normal thicknesses of PVB sheet are 0.38 mm (single), 0.76 mm (double), 1.14 mm, 1.52 mm and 2.28 mm

polyvinyl chloride (PVC)

This is an amorphous thermoplastic. It is hard and brittle and so plasticisers and stabilisers are added to make it softer, mouldable and suitable for technical applications. PVC is well known for its use in floor coverings, cable insulation and gramophone records.


A roof defect. Roofs always drain to the lowest point. But a mistake in the design can lead to areas from which the water cannot drain away completely; ponds of water collect. Attention should be given to ensuring effective drainage during the design of complex roof forms.

pore sealing of anodised aluminium

This is a post-anodising hydrothermal treatment that reduces the porosity and the absorption capacity of the oxide layer and hence at the same time enhances the chemical resistance.


A post is a vertical component. As part of a post-and-rail façade it divides a façade into vertical sections. The posts support the glass and carry the wind loads acting on the glazing.

post-and-rail façade

A glass façade in which the panes of glass are fitted between vertical posts and horizontal rails. This system allows the construction of delicate glass façades. Steel, aluminium or timber can be used for the loadbearing members. Also known as stick system façade.

pot-life test

A test for assessing the quality of the mixing of structural glazing silicone.

powder adhesive

Industrial manufactured powder, e.g. based on cement, that is mixed with a certain quantity of water. It cures hydraulically, which is why powder adhesives are permanently water-resistant. Synthetic additives can improve the properties.

powder coating

A coating process in which an electrically conductive material is coated with a paint in powder form. Steel, galvanised steel and aluminium are typical substrates for powder coating. It is used to protect against corrosion and also for appearance purposes (colour to suit customer specification or chosen from the RAL chart).

powder-actuated fastener

Powder-actuated fasteners are used to connect components, e.g. cold-form steel sections to steel or reinforced concrete. Different fastener types are available to suit the different applications – for both detachable and permanent connections. They are “shot” through the part to be connected and into the other part with a special hand-held gun.


In this process the material is given a very thin, porous anodised finish prior to powder coating. This prevents filiform corrosion, a form of corrosion that only occurs in the immediate vicinity of bodies of water, however. See: anodising.

precast concrete panel

A multi-layer façade panel made from a thin-wall concrete element with a high loadbearing capacity. The prefabrication enables a high surface quality to be achieved.

precast concrete window

A window with a slender concrete frame, normally provided with a fixed light but also available with opening lights. Such windows are supplied prefabricated and ready to install.

precompressed foam sealing tape

This is a foam profile impregnated with a synthetic polymer which is fitted into a joint in its precompressed state and then allowed to expand gradually so that it fills the joint completely, creating a seal against air, dust, small amounts of fluids, etc.

predetermined breaking point

A predefined, prepared point at which a component fails in the event of an overload. The position is chosen to cause minimum damage.

prefabricated spandrel panel

Factory-made non-storey-high component consisting of assembled elements, including infill panel(s).

prefabricated spandrel panel

Factory-made non-storey-high component consisting of assembled elements, including infill panel(s).


A high degree of prefabrication can reduce the erection time on site. Prefabrication is a very important aspect of unitised façades and can have a positive influence on the entire sequence of building operations. The maximum size of a prefabricated element is mostly determined by the transport options and lifting equipment available.

preliminary cleaning

The initial cleaning of a façade following erection.

press brake forming

This is a method for bending sheet metal to a specific angle. The size of the angle is set by the force of the press and the use of various punches and dies. Sheet metal should be bent perpendicular to the direction of rolling whenever possible in order to prevent cracking along the irregularities that occur in the direction of rolling.

pressed glass

A glass product that is produced by pressing a plain plunger into a (normally) patterned mould. Compressed air can be used as an alternative to the plunger. Hollow glass blocks represent an example of a pressed glass product.


A forming process. We distinguish between sheet metal forming and solid or massive forming. In the latter, the process begins with a cylindrical blank that is worked either hot (compression moulding, extruding) or cold (cold upsetting, impact extrusion).

pressure compensation

Pressure compensation is necessary in the case of the installation and/or transport of insulating glass at high altitudes (> 600 m above the place of manufacture of the insulating glass). This is carried out via valves built into the hermetic edge seal.


The introduction of a prestressing force in a cable structure enables the cables to accommodate compressive forces within the scope of the prestressing force. The prestressing force can be degraded by factors such as temperature, relaxation or displacement/yielding of the supports. The objective of designing a cable loadbearing structure is to ensure that the cables remain stressed regardless of the load case.

prestressing steel detection

Non-destructive testing methods for locating the prestressing tendons in prestressed concrete components. There are various ways of magnetising the prestressing tendon and measuring the magnetic field at the surface of the concrete.


This process involves eliminating the plastic deformation of a cable prior to it being built into the structure. In addition, the loss of stressing force due to relaxation phenomena in the built-in condition is reduced to a minimum. Only prestretched cables are permitted in façade constructions.

price comparison

In purchasing, a price comparison is the compilation of the quotations of various suppliers for a particular inquiry.

price level

A tabular overview, produced by the purchasing department, which shows the overall prices and any special aspects of the various tenderers bidding for a given tender.

primary façade

In a double-leaf façade this is the thermally insulating leaf, normally the inner leaf. It is the original, first façade which has a second façade (outer leaf) erected in front of it.

primary structure

The main loadbearing part of a building or component. The primary structure transfers the loads safely to the foundations. It usually also provides the stabilising functions for the building or component. Glass functions as the primary structure in structural glazing.


A bond enhancer between steel and a coating material that would otherwise not adhere properly to the surface of the steel, if at all. Primers provide excellent protection against corrosion.


A type of glass that can be switched between opaque and transparent at the flick of a switch. It therefore guarantees privacy whenever necessary but provides users with a view through the glass like a normal window at other times.

pro forma invoice

This is a document requested by the recipient not for reasons of payment, but as a pure formality. It is issued, for example, in order to declare the value of goods supplied and is then used for tax purposes. In the case of exports, this enables goods to be supplied free of charge to the recipient and the custom duties remain unaffected.


A parametric 3D CAD software, also often referred to simply as Pro/E. All objects are modelled three-dimensionally so that drawings can be produced and/or several objects combined to form subassemblies. This software is used within the seele Group for handling projects with complex geometries.

profiled glass

A special form of glass cast in a U-shape. Manufactured according to the continuous rolling method with/without surface pattern, with/without wire inlay. The structurally beneficial form enables large spans to be achieved. Also known as channel glass.


A rolled glass in the form of a channel section (wide web, narrow flanges). It has a patterned surface and can also be supplied with a wire inlay.

proof stress

This is the stress at which a certain strain in the material can be accommodated. It specifies the stress at which plastic deformation of the material starts to take place. The 0.2% proof stress is normally used as a characteristic value for steel in structural analyses.

property developer

A company or commercial organisation that purchases plots of land for the building of turnkey dwellings. These premises are then offered for sale.

protective glass

A class of sheet glass that owing to its special configuration or special surface treatment can totally or partially reflect and/or absorb heat, UV radiation, sound or radioactive radiation.


An initial sample or model, e.g. of a façade element, from which a batch or series of products is developed.

prototype façade

A prototype of a façade is produced in order to check the design and form and to test the minimum constructional demands placed on the façade. It should include all the essential elements and connections in full detail.

public easement

The voluntary assumption of a public-law obligation.


The manufacture of flat products from various materials (sheet metal, cardboard, textiles, etc.) with a press or sheared off with a cutting tool. Shearing is the cutting principle used here.

purchasing schedule

This is the procurement timetable for the materials necessary for a project. A purchasing schedule is an obligatory part of project management at seele.


This is a PUR recycled granulate (rigid polyurethane foam) with a high compressive strength and a thermal conductivity (?) of 0.07 W/mK. It is used, for example, in panels or window frames with a high thermal insulation value.

putty glazing

Glazing with putty is a simple and also the oldest method of providing a secure linear support for a pane of glass. The putty provides a load-transfer fixing between the glass and the frame, and at the same time waterproofs this joint. UV radiation causes embrittlement of the putty, which leads to a loss of elasticity. This gradual hardening of the support can lead to breakage of the glass.

pyramid roof

Roof form square on plan and with four surfaces that slope inwards to a point.

quadrant-vault roof

A roof form in which the roof surface corresponds to a quarter-cylinder. This is similar to a monopitch roof, but with a curved roof surface. Also known as a half-barrel-vault roof.


Abbreviation for Quality Label for Anodic Oxide Coatings on Wrought Aluminium for Architectural Purposes. This is an organisation that formulates rules for upholding and improving the quality of anodising on aluminium and its alloys for architectural applications.


An organisation that formulates rules for upholding and improving the quality of paint finishes and coatings on aluminium and its alloys for architectural applications.


EN ISO 9000:2005 defines quality as the “degree to which a set of inherent characteristics fulfils requirements”. It goes on to say that quality is only possible when all personnel realise the importance of their work and perform their work exactly and conscientiously, even if they are dealing with only a very small area.

quality assurance

Standards or approvals specify which material parameters manufacturers must monitor at which intervals. In addition, these values must be checked by independent bodies at regular intervals.

quality control (QC)

Measures designed to guarantee that a product or service achieves a predetermined standard. According to ISO 9000 the objective is not to optimise the quality of a product, but rather to maintain a given, possibly even a low, standard.

quality management (QM)

Measures intended to improve products or services of any kind. The quality of products or services must be maintained and further developed.

quality management manual

A document in which the quality management system of an organisation is specified.

quality policy

DIN EN ISO 9000: 2000 describes this as the overriding intentions and orientation of an organisation with respect to quality as formally expressed by the organisation’s management.

quartz sand

Used in the glass industry for producing sheet (float) glass and pressed glass, also in the casting industry and in manual casting as a moulding sand. Low-iron (i.e. extra-clear) glass can be produced by using low-iron sands (< 0.03 % iron). Fine quartz sands with a particle size of 0.1–0.4 mm are mostly used in the smelting furnace.

quenching (metallurgy)

A stage in the heat treatment of metals, especially steel.

radar signal attenuation

The aim of this is to reduce primary and secondary radar signals reflected from buildings. The specifications for radar signal attenuation on buildings are stipulated by Deutsche Flugsicherung (German Air Traffic Control).

radiation shielding glass

Sheet glass that absorbs or reflects certain wavelengths of the solar spectrum.

radiation shielding glass

With a 70 % lead content, this type of glass offers optimum protection against x-rays for personnel in hospitals and industry, and is mainly used within buildings where dry, heated air is the norm. However, it can be made up into an insulating glass unit for use in external walls.


A rail is a horizontal component. As part of a post-and-rail façade it carries the weight of the panes of glass. To do this, supports, usually steel flats, are fixed to the rails. The rails also help to carry the wind loads acting on the glazing.

rain-and-wind-induced oscillations

Oscillations that can occur in exposed tensioned cables.

rainwater downpipe (RWP)

Generally vertical, external pipes for draining rainwater from roof surfaces, balconies and loggias.


The standardisation system of the RAL institute. RAL numbers were introduced in order to bring together various shades of colour in one standard. Every shade has been allocated a four-digit number and the standard is based on a table with 40 shades. The advantage of this standard is that it simplifies communication between customers and suppliers.

rapid prototyping

A method for producing a workpiece (moulded part) directly from a 3D model without long fabrication times. The workpiece is built up layer by layer until the final form is achieved. Different properties may be required depending on the particular process.

raw materials for glass

The following principal raw materials are required for the production of soda-lime-silica glass, which accounts for approx. 90% of the glass produced today: silicon dioxide (SiO2, quartz sand), sodium carbonate (Na2CO3, soda), calcium oxide (CaO, quicklime).


This is the part of the frame that houses the edge of the glass.


This is the area between the inner and outer seals in a glazing unit. seele develops rebate drainage and ventilation systems specific to each project in order to guarantee the sealing function and good durability.

rebate ventilation

An obstructed flow of air must be guaranteed in the rebate for glass in order to prevent condensation in the edge cover area.

rebate width

The total of the dimensions for the thickness of the glass pane and the sealing material in front of and behind this.

rebate-fitted shoot bolt

A shoot bolt is a self-locking device for double doors. It is also permitted on fire and smoke doors. When the bolt is released, a spring is tensioned which is then released by an auxiliary bolt upon closing the door and operates the shoot bolt at top and bottom to lock the door again.

recrystallisation annealing

This process is used when a microstructure distorted by cold-forming is to be returned to its undistorted state. Several hours of annealing at 550–650°C results in a completely new microstructure.

redundant structure

In a redundant structure one element can take on the function of another that has failed.


The REFA-Verband für Arbeitsgestaltung, Betriebsorganisation und Unternehmensentwicklung e.V. is the oldest body responsible for work design, industrial organisation, company development and further education.

reference panel

This is a suitable surface on a structure that is set up in order to specify a binding standard of execution for the coating works and to verify that the stipulations of a manufacturer or contractor are correct for assessing the behaviour of the coating at any time.


This describes the quantity of radiation that is returned after striking the surface of the glass.

reflective coating

A metallic coating applied to one side of a pane of glass.


A light beam is refracted as it passes from air into glass. The angle between a vertical line and the incident light beam is known as the angle of incidence. The angle between a vertical line and the refracted light beam is known as the angle of refraction.

refractory materials

This is the generic term for ceramic materials with a high melting, or rather softening, point, high thermal shock resistance and good chemical resistance.


Rehabilitation returns a building to a usable condition. In doing so, the function of the building is usually changed.

reinforced concrete

A composite material made of concrete and steel reinforcement. The composite action is achieved through the bond between the binder (cement) and the ribs on the steel reinforcement.

reinforced laminated glass

Reinforcing elements embedded in the interlayer of laminated safety glass (also laminated safety glass made from toughened safety glass) guarantees a high residual loadbearing capacity, even with high component temperatures. The following reinforcing elements are conceivable: steel wires and meshes, perforated plates, etc. Reinforced laminated glass is currently still at the development stage.


This is the strengthening of an object by another object that has a higher tensile or compressive strength or a greater durability with respect to other outside influences, e.g. water, frost, chemical substances, etc.

reinforcing bar, rebar

This type of steel in the form of bars or meshes is cast into concrete to form reinforced concrete.

reinforcing bar, rebar

This type of steel in the form of bars or meshes is cast into concrete to form reinforced concrete.


This is the capacity of a material to dissipate the stress at a constant strain.

relaxation prevention

Such a fitting ensures that the preload in a fastener is essentially retained over the lifetime of the connection. The fastener cannot become loose at all. Serrated washers represent one method.

relaxation time

This is a term taken from viscoelasticity theory for describing the viscoelastic material behaviour of, for example, glass at the glass transition.

remote servicing/maintenance

This is access to systems for maintenance and repair purposes by technical personnel from a remote location.

renewable energy

This is energy obtained from a source that either renews itself over the short-term or the use of which does not result in depletion of the source. Renewable energies include water power, solar radiation, geothermal energy and the tides.

residual loadbearing capacity

The property of a glass element to be able to carry certain loads even after breakage. Residual loadbearing capacity is an important factor in the design of glazing for constant foot traffic, glazed safety barriers and overhead glazing. Various regulations regarding length of time and magnitude of loads must be complied with depending on the particular situation.

residual stability

The property of a glass element to be able to remain in position and not fall for a defined length of time after breakage – provided no further loads are applied.


A term used in the formatting of graphics. It is the number of dots per inch (dpi) with which an image can be presented.

restrained support

A restrained support fixes a building component in position. Such a component cannot be displaced either vertically or tangentially. A restrained support resists normal (axial) and tangential forces.

reticulated glass

Reticulated glass is a type of glass made from net-like glass threads.


This is the vertical surface of a wall at the side of a door or window opening.

revolving door

A door consisting of three or four leaves rotating about a common axis in the centre of a circular enclosure with openings on the inside and outside.

ribbon façade

A ribbon façade is essentially characterised by rows of continuous windows between continuous plain spandrel panels.

ribbon size

The ribbon size is the width of the band of glass without trimming. The standard ribbon size is 3.21 m. The limitations of production mean that wider glass formats are only available to special order. The standard lengths are currently 6.0 and 7.2 m, occasionally 9.0 m.

ribbon windows

An uninterrupted row of windows. See: ribbon façade.


The ridge is the horizontal intersection of two roof surfaces that slope downwards from this line.

rigid foam

A foamed plastic (polystyrene, phenolic resin, polyurethane) that is used as a thermal insulation material. Rigid foam boards are preferably used together with floating screeds in order to improve the impact sound insulation and for the thermal insulation in external wall thermal insulation systems.

rigid glass fixing

A type of point fixing in which the pane of glass is held rigidly. The fixing moment acting on the pane of glass must be taken into account in the design. Rigid glass fixings represent a disadvantageous form of support for large-format panes.


The vertical dimension between the eaves and the ridge of a roof or roof surface.


A plastically deformable, solid cylindrical fastener. Cold riveting is the formation of a shear connection between two components. In hot riveting the connection is almost exclusively in the form of a tension connection. Rivets are used mainly for connecting sheet metal components.

Rockwell hardness

A hardness testing method developed in 1920 and named after the American engineer Stanley Rockwell. The Rockwell hardness of the material depends on the indentation depth of a test body (hard steel ball or diamond cone) pressed against it with a certain initial and testing force. The indentation body is pressed into the specimen in two stages and the Rockwell hardness is derived from the additional depth of indentation.


A cylindrical or shaped body used as a forming tool for metals. We distinguish between work and back-up rolls.

rolled glass

Rolled glass is generally produced on a production line by way of casting and rolling. It can be manufactured with and without a wire mesh inlay, in clear and coloured versions, and with a patterned surface on one or both sides. This type of glass is light-permeable and transparent and the view through can be affected. It can scatter or redirect the light depending on the pattern. Also known as cast glass.

roller bearing

This is a machinery component that transfers a load between two contrarotating surfaces with minimal friction. Two contrarotating components, the inner and outer races, are kept a certain distance apart by rollers.

roller waves/indentations

These are corrugation-type distortions on the surface of thermally toughened glasses. They are caused by the rollers on which the hot glass rests during the toughening process. The waviness is due to the production process and depends on the thickness of the glass and the manufacturer’s technical equipment. DIN EN 12150 specifies the permissible local waviness.

roof covering

The roof covering is laid over the roof structure and forms the outer termination of the roof construction. Some forms of roof covering, e.g. clay tiles, are rainproof, but not waterproof.

roof pitch

Usually specified in degrees, occasionally as a percentage. The roof pitch designates the fall (the steepness) of a roof surface.

roof structure

The loadbearing part of the roof construction.

roof structure

The loadbearing part(s) of a roof construction. In a timber roof this is the entire construction responsible for supporting the rafters.


This is the upper layer or layers of a roof that provides a weatherproof surface. The roof covering is laid over the roof structure and forms the outer termination of the roof construction.

roughcast plate glass

This is a form of rolled glass. In the past this was a preliminary stage in the manufacture of polished plate glass.


German abbreviation for frame-mounted door closer (Rahmentürschließer).


Rust is the colloquial name for the corrosion of iron or steel caused by the metal’s oxidation in the presence of water. Rust is porous and does not protect against further decomposition. Iron-based materials exposed to the weather cause damage that runs into billions every year.

sack of glass beads

A test body used for testing glazing intended for limited foot traffic.

sacrificial anode

A non-noble metal used to protect functioning parts against corrosion.

sacrificial casting

A cast part that is produced at the start of a series of castings and subsequently tested to destruction in order to verify the material properties.

safety barrier

A construction or components on a building designed to prevent a person falling from a higher level to a lower level, e.g. temporary edge protection systems, spandrel panels, balustrades, also panels made of glass.

safety foil, security foil

This foil is usually bonded between two panes of glass, but it is also possible to retrofit such a foil on the outside. The primary purpose of the foil is to prevent fragments of glass from becoming detached in the case of breakage.


In this technique the surface of the glass is not given different levels of matt finish as with acid-etching, but instead abraded to a deeper level. The surface of the glass is worked with grains of sand and corundum under high pressure. The surface texture is categorised according to the particle size. Sandblasting has a coarser effect than acid-etching.

sandwich panel

The sandwich construction normally used in the building industry consists of a foam core and two metal facings. The bond (adhesion or adhesive) between the facings and the shear-resistant core gives the sandwich panel a high load-carrying capacity and high stiffness.

sapphire glass

This is the hardest of all types of glass and is made from a synthetic sapphire material.


A glass surface treatment involving acid-etching or sandblasting.

sawtooth roof

A roof form that is primarily used on buildings covering a large area, e.g. factories. A succession of small monopitch or duopitch roofs enables the overall height of the roof to be minimised. Also known as northlight roof.


A scaffold is a temporary, generally reusable auxiliary construction made from (mostly) standardised timber or metal components which is used as a working platform or protective screen.


See: scaffold.

scaffolding concept

Complex building envelopes require involved scaffolding for erection. A good scaffolding concept can help to reduce the cost of erection. For example, mobile scaffolds can save valuable setup and dismantling time.


In technical contexts this is the relationship between the portrayed size and the real size of an object. Architectural and engineering drawings normally employ scales between 1:1 (details) and 1:500 (GA drawings, external works).

scale formation

An oxidation process that takes place above approx. 500 °C, e.g. during hot working and heat treatments. Scale formation is a form of corrosion of a metal caused by a direct reaction with oxygen.

scrap metal

Waste material with a high metal content which is used not only as a coolant, but also as a so-called secondary raw material in the production of steel.

screw channel

A narrow channel into which a screw can be inserted for fixing a façade frame member.

screw thread

This is a continuous helical structure on the inside or outside of a cylinder. It converts a rotational movement or force into a linear one, or vice versa.

screw/bolt retention

A measure to prevent a screw or bolted connection from becoming loose or detached as a result of external influences, e.g. vibration, corrosion, yielding. This is usually achieved by including additional components (usually also preloaded like the connectors themselves), attaching special fittings or by applying an adhesive.

sealant fillet

A sealant triangular in cross-section that fixes the glass without the use of a glazing bead.

seamless pipe

This type of pipe is manufactured from solid pre-hollowed or pre-drilled blooms or billets in the hot state. The first step is the production of a short, thick-wall tube blank. In the following operation this is drawn into the finished pipe.

second moment of area, moment of inertia

This is a measure of a section’s resistance to bending. It is needed to calculate the deformation of a component.

secondary structure

A secondary structure does not carry any loads from the primary structure. The failure of the secondary structure results in partial collapse of the building or component only. Typical secondary structures are: floors and walls not contributing to the stability of the building, rooftop structures and façade elements. Glazed safety barriers are also secondary structures.

section modulus

Related to the extreme fibres of the cross-section through a linear member, this is the second moment of area divided by the distance between extreme fibre and axis of bending. The bending stress at the extreme fibres is calculated with this value (bending moment divided by section modulus).

section rolling mill

A facility for producing sections and straight bars. Each stand in a rolling mill has two or three rolls. Grooves are cut in the body of each roll to match the section(s) to be rolled.


Glass represents the very soul of seele. The name seele stands for ingenuity, innovation, seminal perfection and the very highest quality where glass is concerned. seele co-operates worldwide with renowned architects and clients and is always striving to turn the impossible into reality. This is why seele has become established as a reliable partner.

Sefix retainer

Sefix is a trade name of seele. It is a fixing for attaching a pane of glass to its supporting framework. It is in the form of a retaining plate that is fits into a recess in the edge seal of an insulating glass unit. It is secured by an upturned U-section piece. Once it has been fitted and the joint between the panes sealed with silicone, the Sefix retainer is no longer visible.


Segregation occurs in unkilled steels. This flaw impairs the welding suitability. Segregation zones are primarily found in the flange-web transitions of I-sections, or in the middle of strip steel. However, killed steels are used mostly these days and so segregation is rare.


This is a trade name for toughened safety glass. Sekurit® was the first glass of this type worldwide.

selective corrosion

Also known as dealloying or selective leaching, this is a type of corrosion in which a component of an alloy is preferentially leached from the material. Selective corrosion is the generic term for corrosion forms such as intergranular corrosion and exfoliation corrosion.


Selectivity S is the ratio of the light transmission is TL (in %) to the total energy transmittance g (in %): S = TL/g.

selectivity index (S)

In the glass industry this designates the ratio of the light transmittance Tv to the total energy transmittance g.

self-cleaning glass

This new type of glass, which requires less cleaning, is made possible by a specific modification of the surface. Hydrophobic, hydrophilic or photocatalytic properties or the lotus effect can be exploited.

self-drilling screws

Self-drilling screws are used for connecting materials with different degrees of hardness. They can be used for connecting plastic sheets to a metal framework, for example. Self-drilling screws have an additional drill point at the end that drills the pilot hole. They can bore through sheet metal up to 10 mm thick.

self-locking nut

This type of nut has a ring of plastic in a groove on one side which fits tightly around the thread upon tightening and therefore prevents the connection becoming loose or detached, e.g. due to vibration. Such nuts can be used once only and cannot be used at high temperatures.

semi-finished product

This term covers prefabricated raw material forms such as sheet metal, bars or tubes. These are further processed to form the final products. Semi-finished products are often produced from metals or plastics according to general standards.


This is a central computer on which one or more computer programs are running.

service life of insulating glass

Insulating glass reaches the end of its useful life when the amount of water vapour that has infiltrated the hermetic edge seal is such that the absorption capacity of the desiccant is exhausted and therefore condensation between the panes is a permanent feature.


Part of a structural analysis. It designates the maximum deformation at which the function of a component is still guaranteed. One example is the maximum permissible deformation of the supporting construction for insulating glass. In the case of excessive deformation, the insulating glass can become pervious and no longer fulfil its function.

setting block

Setting blocks carry the weight of the pane of glass. They must distribute the weight of the glass over the frame so that it can support the pane of glass and additional stresses are ruled out.

setting block

Setting blocks are used with glazing units in order to fix the position of the unit within the frame in such a way that the load is transferred via the fixings to the frame construction, or via the hinges of opening lights.

SGP interlayer

SentryGlas® (SG) from DuPont™ is a sheet material that exhibits a much higher strength than conventional PVB interlayers, even at temperatures exceeding 70°C. It has been used in Europe since 2002.

shading coefficient

A variable that is needed for calculating cooling loads according to VDI Technical Rule 2078. The following applies: b = g/0.8. Also known as b-factor.

shading factor Fc

The Fc value describes the degree of shading provided by a sunshade. It is specified in the form of a value between 0 and 1. The lower the value, the greater the sunshade reduces the amount of incoming solar radiation.


This is the trade name for a façade shading system that consists of glass louvres that track the position of the sun. The sunshading effect is a result of the reflection and absorption properties of the louvre material.

shadow box

A coloured piece of sheet aluminium or a panel behind the insulating glass of a glass façade. It conceals concrete floor slabs or suspended ceilings behind the façade. The visual effect of depth behind the insulating glass remains when viewed from outside.

shape charge

A surcharge added to the price when panes of glass are not square/rectangular, but instead are of a non-standard shape. As rule, a surcharge, a percentage of the total price of the pane, must be paid to the supplier of the glass. The surcharge is normally between 10 and 250 %. Also known as pattern charge.

shatterproof window film

A transparent film that can be applied to float glass to give it properties similar to laminated safety glass. If the glass is damaged, the fragments of glass are held in place by this viscoplastic material.

shear force

An internal force in a building component. There is a relationship between load, shear force and bending moment. Shear forces are internal forces that manifest themselves in the form of shear stresses. Shear forces need to be taken into account in the design of sections.

shear strength

This is a body’s resistance to tangential shearing forces. The shear strength designates the maximum shear stress with which a body can be loaded without being sheared off or through.

shear-resistant edge seal

In a shear-resistant edge seal the inner and outer panes of a glazing unit are bonded together via a structural member. This improves the stability of the entire glazing unit. See: hermetic edge seal.

sheet copper

A flat product made by rolling which is used as a roof covering, for pipes and gutters and for other roofing and plumbing purposes.

sheet glass

This is glass that has been produced as a flat pane for use directly as a window etc. but also as the raw material for mirrors, vehicle glass, etc. Sheet glass is used for many applications in the building industry.

sheet metal

A flat product in thicknesses from 0.35 to 3.00 mm: cold-rolled flat products made from soft steels for cold-forming, cold-rolled strip and sheet, general engineering steels, soft unalloyed steels for enamelling, also higher-strength grades plus flat products with metallic or organic coatings in the above thicknesses.

sheet metal development

A flat development of the finished sheet metal part is required in order to produce a bent or folded sheet metal component from one piece.

sheet metal forming

Types of sheet metal forming include bending, deep-drawing, drawing and stamping.

shell structure

A planar loadbearing structure in single or double curvature which can accommodate in-plane and out-of-plane loads. A shell structure minimises the amount of materials needed for a loadbearing construction.


A zinc diffusion method for forming zinc-iron layers on workpieces containing iron, which helps to prevent corrosion.

shielded metal arc welding (SMAW)

This method of welding, also known as MIG or MAG welding, is a semi-automatic type of arc welding in which the consumable bare wire electrode is fed continuously by a variable-speed motor. The gas mixture is fed to the welding point from a nozzle simultaneously with the wire feed.


Intermediate pad of metal or plastic. Shims are used during erection and assembly to compensate for the manufacturing tolerances of components.

ShockWatch® indicator

This damage monitoring system is used by the seele group primarily during the transport of sensitive products. The indicators are in the form of labels attached to the packaging which react to vibrations. In the event of damage during transport, e.g. to panes of glass, it is possible to use the label to find out who caused the damage in the transport chain.

Shore hardness

The Shore hardness, named after Albert Shore, is a material parameter for elastomers.


This is a surface treatment method in which small metallic, glass or ceramic particles are blasted against the surface to be treated by means of a centrifugal wheel, compressed air or spray equipment.

shrinkage allowance

A casting cools and in doing so the material shrinks, i.e. contracts. The pattern must therefore be larger than the finished workpiece by an amount equivalent to the shrinkage allowance. So-called shrink or contraction rules are therefore used.

side-hung door

A door that is fixed via hinges to a frame on one side and which rotates about the axis of the hinges.


German abbreviation for Sicherheits- und Gesundheitsschutzplan (health and safety plan). It serves to implement EU Directive 92/57/EEC regarding minimum health and safety requirements on construction sites.


German abbreviation for Sicherheits- und Gesundheitsschutzkoordinator (health and safety coordinator). This person is appointed by the client for those building sites where the total number of person days exceeds 500 (in other words, 20+ personnel for 30 days). The health and safety coordinator must specify, coordinate and ensure compliance with measures necessary for industrial safety and healthy working conditions. See: SiGe-Plan.

silicate glass

Glass with silicone dioxide as the main constituent. Silicate glass accounts for by far the largest share of glass production and encompasses lead glass, borosilicate glass and soda-lime-silica glass.


This element is a metalloid (semi-metal) which exhibits properties of both metals and non-metals.


Silicone is the designation for a synthetic polymer in which silicon atoms are bonded via oxygen atoms.

silicone dioxide

This is a collective term for the modifications of the oxides of silicon with the empirical formula SiO2. Silicon dioxide is a fundamental constituent in the production of glass.

silicone joint

A silicone joint is an elastic connection between building components achieved with the use of silicone-based sealants. These belong to the group of elastomers. They are elastic and also poor conductors of electricity. They may not, however, be regarded as a vapour barrier.

silicone sealing

UV-resistant silicone is used to seal an insulating glass façade in which the hermetic edge seals are exposed to sunlight.

sine wave

The output wave form of an electric alternating current. An optimum sine wave is characterised by a consistent, defined wave form above and below zero.

single thickness sheet glass

An old designation for glass 2 mm thick.

single-bay ventilation

Each bay of the façade is ventilated separately and any water drained to the outside from each individual element.

single-component glass

This is a special type of glass consisting of just one chemical constituent.

single-ply ETFE

See: ETFE.


Sintered materials are produced from metal powders that are formed into workpiece blanks under high pressure which then undergo a heat treatment, i.e. sintering, in order to achieve their final strength.

site diary

A record of the activities carried out on a building site which forms the basis for invoicing dayworks.

site facilities

These are the buildings, equipment and plant required for the establishment and operation of a building site. Site facilities include cranes, stores, sanitary installations, water and power supplies, and security measures.

skin pass

A reworking process used on hot-rolled deep-drawn or special deep-drawn sheet metal to achieve a bright surface by way of cold rerolling.


German abbreviation for shear/bearing connection (Scher-Lochleibungsverbindung). The fastener can be loaded in tension and shear. An additional retainer should be allowed for because of the lack of a preload.


Solid crude steel with a rectangular cross-section. The width must be equal to at least twice the thickness. This is a semi-finished product from which sheet steel and hot-rolled strip is made. We distinguish between slab ingots and roughed slabs.


The steel reinforcement in reinforced concrete often prevents the accurate positioning of holes drilled at a later date. To overcome this problem, a tube or similar item is cast in between the reinforcing bars. This guarantees that the holes required are available in the right positions at a later date.


A term important in structural engineering. A measure of the stability of components such as concrete columns or steel stanchions. See: buckling.

sliding bearing

This is an element that is based on the sliding movement (guiding) of a component on or in a support. Such bearings generally rely on lubrication to prevent sliding friction. The materials must be matched with one another depending on the load and speed.

slip band

Slip band is a term used in materials science. It is also called persistent slip band (PSB). Slip bands are structures in metals in which the deformation is concentrated due to an external load.


German abbreviation for close-tolerance shear/bearing connection (Scher-Lochleibungs-Passverbindung). The use of a close-tolerance fastener enables higher forces to be transmitted than would be the case with otherwise equivalent types of connection. Other constructional requirements, e.g. the play in the hole, must be complied with. An additional retainer should be provided.


German abbreviation for shear/bearing connection with preload (planmäßig vorgespannte Scher-Lochleibungsverbindung). The fastener can be loaded in tension and shear. The application of a preload makes additional retainers superfluous.


German abbreviation for close-tolerance shear/bearing connection with preload (planmäßig vorgespannte Scher-Lochleibungs-Passverbindung). The load-carrying capacity is higher than that of an equivalent connection without a close-tolerance fastener. The application of a preload makes additional retainers superfluous.


Abbreviation for Standard Motor Interface. This is a uniform interface in building automation for controlling electronic drives. It is used, for example, in louvre blinds, roller shutters, etc.

smoke and heat vent

This is an installation intended to remove smoke from the roof and façade areas of public buildings so that in the event of a fire toxic fumes and gases do not collect and persons can find escape routes. These are safety installations and therefore the relevant statutory instruments must be taken into account for their design and construction.

smoke door

This is a self-closing door that is intended to prevent the spread of smoke through a building in the event of a fire. The terminology and requirements for smoke doors are laid down in DIN 18095-1. Also known as smoke-control or smoke-stop door.

smoke penetration rating

Smoke penetration ratings are designated with the letters G for doors and R for fixed glazing followed by the time (in minutes) the construction can prevent the penetration of smoke.

smokeproof glazing (R-glazing)

This is a glass infill panel that resists the penetration of smoke and flames for a certain length of time. When exposed to heat, this type of glass does not break immediately, but keeps an escape route open for a specified period. The fire resistance of R-glazing varies from 30 to 60 minutes (R 30 to R 60).

snap line, chalk line

A traditional tool used in interior works for producing a straight line.

social security contributions

In Germany this currently consists of health insurance (7.9 % employee + 7.0 % employer = 14.9 %), pension contribution (19.9 %), unemployment insurance (2.8 %) and nursing care insurance (1.95 % + 0.25 % for employees aged 23 and over with no dependent children). Employer and employee each pay half of the social security contributions.


A socket is a component that forms a continuous connection between two pipes or cables. A fixing component with an internal thread which is more than twice as long as the internal diameter is known as a threaded socket.


One of seven modifications of the chemical compound sodium carbonate. Anhydrous sodium carbonate (Na2CO3) is used in the production of soda-lime-silica glass and for lowering the melting point of silicon dioxide (SiO2).

soda-lime-silica glass

This is the most common type of glass and is used for producing receptacles and sheet glass.

sodium carbonate

This compound (chemical formula Na2CO3), also known as soda, is a salt of carbonic acid. When used as a foodstuffs additive, it is designated E 500. Sodium carbonate is a fundamental constituent in the production of glass.

sodium sulphate

This compound (Na2SO4) is an additive used in the production of glass – as a fining agent for reducing the formation of gas bubbles. It occurs as a by-product in the chemicals industry during reactions in which sulphuric acid is neutralised with caustic soda.

soft impact

This is a test method for assessing the strength of safety glass when subjected to the impact of a body with a relatively large mass (e.g. pendulum-type impact with twin tyres to EN 12600) but low velocity. This test is intended to simulate the impact of a person on a pane of glass.

soft iron

This is the commonest soft magnetic material and consists of unalloyed iron. Electrical machines (electric motors, generators, transformers, etc.) contain soft iron plates for concentrating or strengthening magnetic fields.

soft/offline coating

Soft coating is a method of coating that is not carried out directly during the manufacture of float glass, but rather in an additional process, normally by way of vapour deposition or magnetron sputtering. Soft-coated surfaces are sensitive to aggressive environmental conditions and mechanical actions.

solar glass

This is a thermally toughened low-iron glass intended for use in photovoltaic modules.

solar-control glass

In this type of glass a suitable coating prevents infrared radiation (heat) and ultraviolet radiation (which causes fading) passing through the glass to the interior. The corresponding coating is applied to surface No. 2 (counted from the outside).

solder glass

A special glass material used for soldering glasses together.


One of the major states of matter. Materials are also regarded as solid when they exhibit structural rigidity and resistance to change in shape or volume at a temperature of 20°C.

solid construction

A form of construction for a loadbearing structure in which the space-enclosing elements such as walls and suspended floors are made of masonry or concrete.

solvent dye

With a solvent dye the colorant forms clear, dissolved silicates in the glass melt. This results in so-called body-tinted glass. The colour effect is due to the absorption of specific wavelengths of light.

sound generation and propagation

Sound ensues when a body oscillates. Sound propagates equally in all directions around the source of the sound unless this is prevented by some obstacle. Sound cannot propagate in a vacuum. On the other hand, it propagates as soon as impacts cause the particles of a body to begin oscillating.

sound insulation

This is specified in numerous DIN standards. In principle the aim is to prevent noise (from services, etc.), to shield against noise from outside (acoustic windows) and to avoid sound transmissions within a building. The frequencies relevant for buildings range from approx. 100 Hz to approx. 4000 Hz.

sound level

This is a ratio, i.e. a dimensionless physical variable. The unit of measurement, decibel (dB), is named after Alexander Graham Bell, the inventor of the telephone.

sound reduction index R

The sound reduction index R is based on a logarithmic scale and specifies the capacity of a building component to restrict the passage of sound. The range relevant to buildings is 100–3150 Hz. Rw is the 10-fold logarithmic ratio of the sound power incident on the building component to the sound power emitted from the component. Halving the sound power corresponds to a 10 dB improvement in the sound insulation.


A hollow metal section of stainless steel or aluminium that keeps the panes of an insulating glass unit a certain distance apart and also provides a container for the desiccant.

spangle pattern

A surface phenomenon that ensues when a zinc coating solidifies.

special tolerances

These tolerances can be realised by employing additional precautions during manufacture and must be agreed in each individual case. The additional work required for these precautions is specified for the respective tolerances and usually associated with extra costs.


A specification is a formal description of a product, system or service. The aim of a specification is to define and quantify features with which the product or service of the supplier can be checked upon being provided to and paid for by the client.

spherical bearing

A special type of bearing used in bridges. Spherical bearings are designed according to the principle of a ball-and-socket joint. They enable significant rotation in a compact form with minimum resistance, especially with varying action effects. This type of bearing can also be used for heavily loaded components in façades.


A colourless, readily combustible liquid with a boiling point of 78 °C. Used as a solvent, as a cleaning agent, for heating purposes and as a fuel additive.

spliced glass fin

Long glass fins can be fabricated in spliced form. This means that the individual butt joints between the pieces of glass are offset (or staggered) in alternate layers to cover the butt joints of the adjacent layer. Glass fins longer than the maximum length of glass available can therefore be fabricated.

split mullion

A special intermediate post design for unitised post-and-rail façades. This member, divided vertically, is placed between the individual elements, each half of which is allocated to one element.

spot welding

An electric resistance welding process for the discrete jointing of workpieces, e.g. steel components, wires in reinforcing meshes, etc.

spread of fire

Spread of fire is the name given to the propagation of fire by flames, sparks or the effects of heat (radiant heat) from one façade opening to another, or from one component to another.


This is a small flat nail used for fixing a pane of glass in a wooden frame.


An engineering component that yields under load but returns to its original form when the load is removed, i.e. it behaves elastically.

spring steel

Steel with a high strength that is used for producing all kinds of springs for an extremely wide variety of technical applications.

spring washer

This steel ring prevents a nut from loosening in the event of vibration.

sputter deposition

In the high-power impulse magnetron sputtering process, a layer of a noble metal is applied to the surface of the float glass after the glass production process.


Sputtering is a coating technique and belongs to the group of physical vapour deposition (PVD) methods. It involves the erosion of material from a “target” solid substance by way of energetic ion bombardment (primarily noble gas ions) in order to coat a substrate with the eroded material. Also known as magnetron sputtering.


The abbreviation for structural sealant glazing – a special application for adhesives. SSG designs use the adhesive to carry the loads. In Germany in particular, comprehensive verification of the durability of the adhesive joint must be provided. SSG façades in which the panes of glass are held in place by adhesive only are not permissible in Germany.

stack effect

The stack effect works on the principles of aerostatics. Hot air has a lower density than cold air, which results in an upward thermal current for the hot air. In a double-leaf façade the captive radiation energy drives the hot air up the façade – the stack effect.

staining, fogging

This is the obscuring (chemical reaction) of the surface of single glazing due to exposure to the weather or the long-term effects of moisture. This effect can occur within the cavity of an insulating glass unit if the hermetic edge seal becomes impervious.

stainless steel

A colloquial name given to a group of corrosion- and acid-resistant steels.

stainless steel net

A metal fabric with a regular mesh, or rather apertures. The individual metal wires can be connected with clips or crimped sleeves.

standard grid

Façades are often divided into regular grids so that many identical elements can be used for a construction. This is very advantageous for fabrication, transport and erection. Perimeter zones often have to deviate from this standard grid because of the transition to adjacent components.

standard thickness

The standard thicknesses of float glass made from soda-lime-silica glass are: 3, 4, 5, 6, 8, 10, 12, 15 and 19 mm. Borosilicate glass is also available in 7 mm, but not 19 mm. Profiled glass is available in 6 and 7 mm only.

standard tolerances

These are all those tolerances that can be guaranteed during normal production sequences.


The advantage of standardisation is the fact that it is easier to work with standardised components because these are interchangeable. To do this, it is necessary for the fundamental properties of standardised parts to be used by central bodies, manufacturers and suppliers.

standby installation

An electricity generation system that in the case of a mains failure ensures a supply of electricity for equipment relevant to safety functions.

Status A

Check symbol attached to a detail drawing by the client or architect. It means that the drawing has been approved.

Status B

Check symbol attached to a detail drawing by the client or architect. It means that the drawing has been approved apart from a number of obligatory corrections; the client must be given a copy of the corrections and the designated check symbols must be followed.


Metal alloys with iron as their principal component and a carbon content of 0.02–2.06% are known as steels. The following applies in normal cases: the strength of the steel, but also its brittleness, increases with the carbon content. As this is the metallic material used most frequently, it is in most cases preferred for the primary structure of delicate façade constructions.

steel angle

A linear steel product with a cross-section in the form of a right-angled letter L (at least the standardised products).

steel bar

Customary term for all products of all steel grades in the form of straight solid bars with a cross-section that remains constant over the entire length. We normally distinguish between rolled, forged and cold-drawn products.

steel beam

Steel beams form the structural framework for many façades. Steel beams are available with various cross-sections, e.g. I-section, T-section, square or rectangular hollow sections. They are produced by means of a continuous casting process and cut to the desired length.

steel construction

The branch of construction in which steel is used as the primary loadbearing material. The possibilities for constructing with steel first appeared in the second half of the 19th century when sufficient quantities of steel first became available. Also known as structural steelwork.

steel deoxidation

Ferrosilicon or aluminium is added to the steel melt during the deoxidation of steel. These metals bond the oxygen that is released as the steel solidifies so that no gas bubbles are formed in the steel ingot.

steel flat

A rolled industrial product made of steel with a rectangular cross-section which has a width much larger than its thickness. According to DIN EN 988, the thickness must remain constant over the entire length of the product.

steel pipe

We distinguish between two types of pipe production: seamless pipes and welded pipes.

steel reinforcement

This type of steel in the form of bars or meshes is cast into concrete to form reinforced concrete.

steel section

Shaped steel (rolled, drawn, pressed) with a cross-section that remains constant over its entire length (bar, I-section, etc.).

steel section

The designation for a steel product with a constant cross-section in the form of an I, H, T or U (channel).

steelyard balance (H-type specimen)

This is a lever mechanism that enables the strength of an H-type tensile test specimen to be assessed inexpensively for structural glazing adhesive joints. The H-type specimens are tested to failure. The tensile strength at failure should be at least 0.70 MPa.

stepped edge

A stepped detail at the edge of an insulating glass unit. One pane projects beyond the other and the edge seal.

stepped insulating glass

In stepped insulating glass the edges of the panes are not flush; instead, one pane overlaps the other. Used, for example, in glazing to roofs. See: stepped edge.

stirring gas treatment of steel

The gas bubbles through the melt, thoroughly mixes this and in doing so drags the impurities to the surface. When argon is used as the gas, this process can replace vacuum treatment. Also known as circulation or rinsing gas.


A water glass product used for waterproofing and silicifying porous concrete and masonry. It is a tried-and-tested means of waterproofing stone, porous, permeable concrete surfaces, plasters and renders. Stonosal infiltrates into the absorbent zones of concrete and mortar and forms silicone resins and insoluble calcium silicates out of unused cement particles.

storage of aluminium

Aluminium products must be stored remote from the anodisation plant prior to and after anodising. They must be protected against condensation and soiling. Stocked anodised parts must be marked with the coating thickness class immediately after treatment.

stove enamelling

Stove enamelling is used to coat aluminium components, e.g. aluminium window frames, with a tough coating, which is dried at high temperatures. The coating also protects the aluminium against corrosion.

strain gauge

This is a measuring device that records the deformation of an object. Even minimal movements change the electrical resistance of the gauge and so they are used to indicate the strain in an object. A special adhesive, which exhibits minimal deformation under load, is used to bond such gauges to building components.

strap hinge

A door hinge that is mounted on the door leaf and door frame so that it remains visible.


This is a material’s resistance to plastic deformation beyond a certain point, or rather its resistance to the propagation of cracks or the abrading of its surface.

stress failure

Glass breaks when the stresses exceed a certain limiting value. The type of load causing the stresses is critical.

stress-relief annealing (glass)

This is a process that enables the distribution of mechanical stresses in a glass component to be influenced in a controlled way. To do this, the component must be heated to just above the lower annealing temperature and then held at this temperature until the whole component has reached this temperature.

strip casting plant

Continuous casting of steel in sizes close to the final dimensions. In this type of plant, thin strip (pre-strip 15–50 mm, strip < 15 mm, thin strip < 5 mm) is produced directly from the melt. The process operates with one or two rolls.


This process is used to remove old coats of paint or varnish from, for example, wood or stone. The application of a liquid or paste-like stripper softens the coating which can then be washed or scraped off.

structural engineering

The design of the loadbearing structure of a building or other constructed artefact. The primary requirement of structural engineering according to construction legislation is to ensure the stability of a building or structure.

structural glazing (SG)

A method of glazing developed in the USA in which the glass is attached to the frame with adhesive, without any external fixing or retaining elements around the edges of the glass.

structural glazing silicone

A chemicals-based, one- or two-part adhesive suitable for a diverse range of applications, e.g. metals, mirrors, sealing the rebates of wooden windows.

structural health monitoring

Long-term observation of buildings and structures. Deformations, support reactions, strains, etc. can be monitored and recorded over a long period of time. The findings can be incorporated directly in new projects. Early detection of damage is also possible.

structural steelwork

The branch of construction in which steel is used as the primary loadbearing material. The structures are constructed from rolled sections, plates and tubes made from engineering steels, and also, a recent development, cast steel parts, all of which are connected together by rivets, welds or bolts to form a loadbearing structure.

stud welding

In this process an electric arc is generated between the end of the stud and the workpiece. Both parts are therefore melted locally and subsequently forced together under pressure.


A subcontractor is employed by the main contractor to carry out part or all of the work the latter has been contracted to do.

submerged arc welding (SAW)

In this welding technique one or more wire electrodes are melted while “submerged” in a layer of flux. The arc that forms between the wire electrode and the workpiece melts part of the flux that collects above the joint to be welded. This process is used for thick plates and long, mostly straight, seams.

submerged arc welding (SAW)

A method of welding in which the arc burns under a protective cover of granulated fused flux.

submission of plans

The presentation of the project drawings to the client and architect, who then inspect the drawings and make comments/corrections as necessary. Afterwards, each drawing is awarded a status that determines the next step.

suction cup

This is a technical device made from a partially elastic material which can be clamped to a smooth, flat surface by means of a vacuum. In façade construction, suction cups are clamped to panes of glass with a vacuum so that they are easier to transport.

sulphur hexafluoride (SF6)

This is a so-called heavy gas which when used in insulating glass can improve the sound insulation.

sunshading system

Façades are usually exposed to direct or indirect sunshine. Therefore, sunshading systems are installed in order to provide shade. Examples of sunshading systems include: awnings, louvres, roller blinds and screens.

sunspace, sunroom

The name given to a large glazed room on the side of a building. Individually designed to comply with aesthetic and technical requirements, this is high-quality glass architecture that fits in neatly with its surroundings and sets standards while providing a high level of comfort for users.


A support is the bearing surface to which the loads carried by horizontal components (joists, beams, suspended floors, etc.) are transferred. The forces acting at this point are known as reactions.

support conditions

In structural analysis these specify which forces are transferred from the structure to the subsoil. Pinned, sliding, spring or fixed supports are possible. The detailing of the junction at the support depends on the support conditions and corresponding movement must be possible in the unrestrained direction(s).

supporting construction

This must be sufficiently stable and must prevent any twisting. It can also ensure air circulation.

surface flaw

This is, for example, a scratch, notch, chip or grinding mark that can lead to a considerable drop in the bending strength of a non-toughened glass.

surface parallelism

The absolute parallelity between two plane surfaces. Float glass panes exhibit this property. In earlier times, a pane of glass with absolutely parallel surfaces could only be achieved through extensive grinding.

surface temperature

This is the temperature that prevails at the surface of a building component. Cold walls and windows are the result of inferior thermal insulation. That reduces the thermal comfort and can lead to the formation of condensation.

surface treatments

Chemical vapour deposition (CVD) and physical vapour deposition (PVD) can be used to apply an ultra-fine metal coating to a glass surface, e.g. to reduce the permeability of the glass with respect to infrared light without impairing the transparency significantly.

surface treatments

Subsequent working of the surface of sheet glass by way of grinding, acid-etching, sandblasting, ice-patterning and enamelling.


In the planning of buildings and structures, surveying records the actual and legal position and constituents of a plot of land.

suspended ceiling

A lightweight ceiling construction mounted below the structural floor. Suspended ceilings are used, for example, in the refurbishment of existing buildings and in very high rooms or to improve sound insulation (by including an additional layer of mineral insulation). They provide good options for the concealed routing of building services.

suspended floor

A (mostly) horizontal component separating adjacent storeys in a building. It forms a trafficable surface for the storey above.

swing door

A side-hung door that can open in both directions.

switchable glass

Laminated safety glass with an interlayer of liquid crystals. Applying an electric voltage aligns the crystals and switches the glass to the transparent state. When the voltage is switched off, the glass has a milky white appearance which guarantees privacy but still allows light to pass through.

system façade

A system façade enables a multitude of façade designs to be constructed on the basis of one system made from identical components. The fabrication and erection of this type of façade is more cost-effective than custom and special solutions.


German abbreviation for the cavity between two panes of glass (Scheibenzwischenraum). In normal cases this cavity is 12 or 16 mm wide. The design of the cavity together with the low E coating essentially determines the U-value of the glazing.


A steel section with only one flange. We distinguish between long-stalk and wide-flange T-sections, which can have either square or rounded corners.


A steel section with only one flange. We distinguish between long-stalk and wide-flange T-sections, which can have either square or rounded corners.

tapered pin

A connector that can be used in a detachable connection.

target-actual comparison

This is a term used in business accounting. It shows the difference between the actual and the budgeted costs. The anticipated profit from a project is calculated from this.

technical drawing

This type of drawing provides information about the form, construction and function of workpieces, subassemblies and systems. We categorise technical drawings as follows according to their content and purpose: sketches, part drawings, subassembly drawings and general drawings.

temper colours

Coloured glasses achieve their colour effects only after additional heat treatment – the glass is annealed. Minute particles form in the glass. The colour effect is due to the absorption or scattering of specific wavelengths of light.

tempered glass

A type of glass in which heat treatment is used to generate mechanical stresses in the material and hence increase its ultimate strength with respect to mechanical or thermal stresses.


This is the reheating of a workpiece after hardening to temperatures below Ac1 (lower critical temperature), holding at this temperature and subsequent cooling. We distinguish between two types of tempering: relieving at approx. 150°C in order to compensate for the stresses that ensue during hardening but without reducing the hardness; tempering at 400–650°C as part of the hardening and tempering process.


This is a design principle for stabilising systems based on a balance between tension and compression forces.

tensile bending strength

The is the maximum tensile stress a material can accommodate while being subjected to bending. The microstructure of the material is irreversibly damaged if the bending stress induced in an element is greater than its tensile bending strength. This can lead to a structural failure.

tensile strength

Material parameter that characterises the tensile force a unit area can accommodate up to failure. Normal unit of measurement: N/mm². The tensile strength is determined by means of standardised tests on standardised specimens.

tensile stress

A term from structural analysis. This is the stress in a component caused by a tensile force. In a reinforced concrete component, tensile and compressive stresses occur at different places. Tensile stresses preferably occur in the bottom in the span(s) and in the top over the support(s).

tensile test

A standardised method of assessing the tensile strength and other parameters of a material. The result of a tensile test is shown on a stress-strain diagram.

terne plate

This is a cold-rolled flat product for cold-working applications. It is made of soft unalloyed steel with a coating of terne metal.


The name given to fired, unglazed clay items such as vessels, sculptures and ceramic products for the building industry. A warm, earthy colouring is also sometimes referred to by this name. Firing once at a relatively low temperature (900–1000 °C) means that the production is not particularly complicated.

tertiary structure

All the components that do not contribute to the load-carrying capacity of the secondary structure but are still required to carry certain loads. These include, for example, the glazing to façade elements and windows.

test certificate

Test certificates for materials or forms of construction are required when these are called for in the specification or individual approvals are necessary. seele employs many innovative designs and so such certificates are part and parcel of our work.

tested mock-up

This is a model made for testing purposes.

textile architecture

This offers many advantages and permits interesting combinations with other materials (timber, glass, concrete and steel). Furthermore, these textile solutions from seele are very popular because of their superior lightness, good durability and recycling properties.

theory of structures

The science of the stability of loadbearing constructions. The methods of calculation and modelling derived from the theory of structures are the tools of the structural engineer.

thermal break

A necessary constructional measure to avoid a thermal bridge. One typical example can be found in the aluminium frame to a window, where a plastic spacer is used to avoid the transmission of heat from the inner to the outer frame sections.

thermal bridge

A thermal bridge (often erroneously called a cold bridge) is an area in a component of a building through which heat flows more quickly outwards or inwards than is the case in the other areas of the component.

thermal conductivity

This specifies how much thermal energy is transported through a material in the form of heat by means of conduction.

thermal elongation

The coefficient of thermal expansion specifies the change in length of a solid body subjected to a temperature change of 1 K in relation to the total length L0.

thermal expansion

Components change their form and volume when subjected to temperature changes. If this fact is not taken into account in the design and construction of a structure, this can result in damage. The magnitude of the change in volume is determined by the coefficient of thermal expansion.

thermal insulation

All measures that reduce the heat transfer between interior and exterior or between rooms at different temperatures.

thermal insulation wool

General term for “soft” thermal insulation materials such as glass wool, sheep’s wool, rock wool, hemp or mineral wool. These products are generally available in the form of batts, fleece, blankets or as loose fill. The latter is used for filling voids and cavities.

thermal shock resistance

This is the capacity of a building material, primarily glass, to withstand larger temperature fluctuations within the body of the material without any damage. The thermal shock resistance of toughened safety glass is particularly notable. Non-toughened glasses exhibit a low thermal shock resistance.

thermal toughening

Float glass is heated to 620–650°C and subsequently cooled very quickly by way of convection from the surface. The rapid cooling process leads to the surfaces of the glass contracting to a greater extent than the inner core. The result of this is that a compressive stress is generated at these surfaces, a tensile stress within the body of the glass.

thermal transmittance (U-value)

The thermal transmittance is the measure for the physical magnitude of a heat flow in building components when different temperatures prevail on the two sides. It specifies the quantity of energy that passes through a surface of 1 m² in 1 s when the difference between the temperatures on the two sides is 1 K. The unit of thermal transmittance is W/m²K. The lower the value, the better the insulating effect.


This is a method measuring the heat lost from a building. The method is based on the fact that every body emits heat depending on its temperature. Using a thermographic image (thermogram) of a façade, for example, it is easy to see that the doors and windows are the weak spots.


Thermoplastics are meltable, high-polymer materials that change to a plastic state upon the application of heat. They can be easily moulded when in this state, and the shape is retained upon cooling. This process can be repeated. Thermoplastics are mostly viscoplastic.


See: thermosetting plastic.

thermosetting plastic

Once they have cured, thermosetting plastics can no longer be deformed. They are particularly resistant to heat and chemicals and cannot be deformed plastically. As there is intensive cross-linking between the molecular chains, thermosetting plastics are hard to brittle at normal temperatures.

thin glass

Sheet or plate glass with a thickness of up to 1.8 mm.

thin-film technology

Method of manufacture for photovoltaic modules which allows them to be used in façades. The elements are so thin that they possess semi-transparent properties. Consequently, it is possible to use façade surfaces for generating electricity.


Thiokol® is a trade name for sealants made from polysulphides. Thiokol® is not UV-resistant and therefore the edge seal must be shielded from the light.

threaded steel bar

Bar with helical, thread-like ribs for use in conventional reinforced concrete or prestressed concrete.


A tie is often used in an arch construction when the supports cannot or should not resist the enormous thrust forces. The tie connects the two outer arch supports in tension.


A member that carries exclusively axial tensile forces, e.g. the diagonals in trusses or bracing. If it can be guaranteed that a certain building component will carry only tensile forces, a more slender section with a low bending stiffness can be chosen and this results in a more delicate appearance.

TIG welding

Tungsten inert gas welding is a process that makes use of inert gases. The electric arc is generated by a non-consumable tungsten electrode. Torch and electrode are usually guided manually. The main applications are high-alloy steels and aluminium materials, but unalloyed engineering steels can also be welded using this method.

tilt-and-turn window

A side-hung window that by means of a special mechanism can also be tilted inwards like a hopper window.

TiltWatch® indicator

This damage monitoring system is used by the seele group primarily during the transport of sensitive products. If shipped goods fitted with these labels are tilted during transport, the indicator field turns red. In the event of damage during transport, it is therefore easier to find out how and where the damage occurred.

timber-frame construction

This is a framework of timber posts and rails with infill panels generally of loam or masonry.

tin bath

In the production of float glass the glass floats on a bath of molten tin. During this process, tin ions diffuse into the surface of the glass and these can be made visible in black light.


A surface treatment in which a coating of tin is applied to (usually) metallic workpieces to protect them against corrosion. Tin-plating is used mainly on workpieces that come into contact with foodstuffs.


Up to 0.5 mm thick sheet or strip steel with a coating of tin applied by electrocoating. It is primarily used for packagings.

titanium (Ti)

In corrosion-resistant steels, titanium is an alloying element that reduces the susceptibility to intergranular corrosion. This effect is achieved through the finely distributed carbides that are formed by titanium. In addition, titanium has denitrifying and deoxidising effects and also bonds sulphur.

titanium oxide coating

Float glass coated with titanium oxide has a dual action, combining two properties in order to achieve a self-cleaning effect. Coating the outside with titanium dioxide reduces the surface tension (hydrophilic) and prevents the formation of droplets.


There is no such thing as absolute accuracy, i.e. the realisation of a given dimension is always associated with deviations. With quality control production, this actual size must lie within permissible deviations. The difference between the upper and lower limits of size is the tolerance.

toll and energy surcharge

A surcharge added to the price for delivery because of the road toll incurred by goods vehicles and higher energy costs. The amount of the surcharge depends on the weight of the glass.


This is the physical variable activated upon increasing or decreasing the speed of rotation of a rotating body. Torque is measured in newton-metres (Nm) and is the vector product of lever arm and force.


The moment of a force with respect to a reference point is the product of the absolute magnitude of the force and the distance of its line of action from the reference point.

torsional strength

This is a body’s resistance to twisting about its own axis. A measure of the torsional strength is the torsional stiffness, which specifies the resistance to deformation.

total energy transmittance (g-value)

This value is defined as the sum of the direct transmission due to solar radiation plus the inward heat emissions due to radiation and convection. Double glazing made from clear glass has a g-value of approx. 0.8.

total reflection

At the transition from one medium to another, not all of the incident light is refracted – part is reflected. The larger the angle of incidence, the greater is the proportion of reflected light. When the angle of incidence reaches the critical angle for total reflection, all the light is reflected. At the transition from air to glass, this critical angle is 42°.

toughened glass

We distinguish between toughened safety glass and heat-strengthened glass depending on the degree of toughening. Either a thermal or chemical process can be used for toughening. Toughening improves the safety properties and load-carrying capacity of the glass.

toughened safety glass

This is a type of glass that has been thermally (to DIN 12150-1) or chemically treated to achieve a better thermal shock resistance plus better bending, impact and shock resistance. (US: tempered glass)


The work stored due to deformation or another type of energy conversion up to rupture.

trace heating

Electric cables can be laid on roof surfaces, in gutters or in downpipes. These prevent the accumulation of snow or formation of ice. Most systems on offer are self-regulating and adapt automatically to the ambient temperature.

trailer-mounted aerial work platform

A lightweight, compact form of elevating platform. Available with articulated or telescopic booms, with or without a so-called basket/bucket for persons, such plant can reach working heights of up to 30 m. When attached to a vehicle with a tow ball coupling, these platforms are easy and convenient to transport. Their low weight means that they are also suitable for surfaces with a low bearing capacity.

transition temperature (Tg)

The softening point of a glass melt. The transition temperature of float glass is about 520°C.


The ability of a material to allow the passage of light but prevent a view through (cf. transparency and opacity).


This is the permeability of a medium with respect to wave forms, e.g. light. It specifies the ratio of the radiation passing through the medium to the radiation incident on the medium.


The ability of a material to allow the passage of light, to allow a view through. The opposite of opacity.


Technische Regeln für die Verwendung von absturzsichernden Verglasungen (Technical Rules for Glass in Safety Barriers). A mandatory German code of practice for vertical glazing elements that must act as a safety barriers to prevent falls. Balustrade infill panels, glass panels fixed at the base and storey-high glazing are among the types of construction covered.

triangulated frame

A framework consisting exclusively of triangles. The advantage is that the framework is always statically determinate internally.

TRIP steel

TRIP stands for transformation induced plasticity. This is a further development of dual-phase steel. TRIP steels can either have higher strengths (up to 850 N/mm²) with comparable elongation, or much higher elongation values with comparable strengths of approx. 600 N/mm².

triple glazing

Three panes of float glass and two intervening cavities, which can be filled with a noble gas (argon, xenon) to improve the U-value. The disadvantages of triple glazing are the high weight of the units and the lower light transmittance.


German Technical Rules for the use of Glazing on Linear Supports (Technische Regeln für die Verwendung linienförmig gelagerter Verglasungen)


German Technical Rules for the Design and Construction of Point-Supported Glazing (Technische Regeln für die Bemessung und Ausführung punktförmig gelagerter Verglasungen)

true density

This is the density of the material part of a body in any state.

true flat roof

A special flat roof form in which the roof pitch is zero.

trussed frame

This is a timber or steel construction made up of several linear members joined together at their ends. This principle results in individual members being loaded exclusively in either tension or compression, and it is this that gives a trussed frame its high load-carrying capacity.

tungsten inert gas (TIG) welding

The welding equipment in this case consists of a power source, which in most cases can be switched between a.c. and d.c., and a welding torch connected to the power source by a hose.

type of loading

Forces that act on a structure can occur in various forms such as point, knife-edge (linear) or uniformly distributed (in two or three dimensions) loads.


This is a German label that confirms that a construction project complies with designated requirements. This confirmation is achieved either through a declaration by the manufacturer (without consulting a monitoring or certification body) or through the compliance certificate issued by an acknowledged institute.

U/A value

Section factor for steel sections. A parameter for determining the thickness of the fire resistant coating/casing necessary for steel sections. It expresses the ratio between the perimeter of the steel section and its cross-sectional area.


The passive solar energy gains, which are only possible with glass, are taken into account in the heating requirement analysis in the form of the Ueq-value.

ultimate strength

In materials science this is the mechanical stress at which an element fails as it is subjected to a constant increase in the load.

ultrasonic weld inspection

This is a widely used non-destructive method for assessing the quality of weld seams in steel, titanium and aluminium assemblies. Cracks, porosity, inadequate penetration, inclusions, lack of fusion and similar defects can affect the durability of a welded joint and the ultrasonic method can be used to find these.

ultraviolet (UV) radiation

Short-wave radiation in the solar spectrum.


This is a failure mode in residual loadbearing capacity tests and occurs in the region of the point fixings of panes of glass (mostly laminated safety glass made from toughened safety glass). Damage to a pane over a wide area means that the region around the point fixing becomes so soft that the fastener can slip through the hole drilled in the glass.

undercut anchor

A special type of anchor in which an interlocking connection is achieved by enlarging the base of the hole with a special drill. The anchor has special wedges that fill the enlarged hole completely when the anchor is tightened.

underfloor door operator

A mechanism for opening/closing automatic doors which is concealed beneath the floor.

uniform corrosion

The surface of a material is approximately evenly and slowly eroded by corrosive effects. This type of corrosion occurs on non-coated exterior components made from unalloyed engineering steels or during the oxidation (scale formation) of forged parts.

unitised façade

This type of façade consists of fully prefabricated elements – usually matching the height of one storey and the width between two grid lines. On the building site these modular elements are moved into position and attached to the structure with adjustable fixings. The advantage of this method is that complex constructions can be assembled, glazed and provided with sunshades, glare screens and lighting in the factory. In contrast to a building site, the conditions in a factory are easily controlled.

unrestrained support

An unrestrained support permits movement in two directions. In the case of bridge structures an unrestrained support on one side is often combined with a restrained support on the other to compensate for temperature fluctuations.

uplift protection

Uplift protection secures roof glazing against the uplift forces exerted by wind suction loads. The glass is carried by linear supports for essentially downward loads (snow, wind pressure, self-weight). Individual, disc-type retainers secure the panes of glass against uplift. These retainers must be considered and designed as point fixings.

upper chord

The topmost member in a trussed girder. Most of the loads are transferred into the girder via the upper chord, which is usually a compression member and therefore has to satisfy stability criteria as well.

uranium oxide

This is a chemical compound of uranium and oxygen Uranium oxide is mixed with the glass during production in order to give it a delicate yellow or green colouring. However, this compound is no longer used because of uranium’s radioactivity.

use of setting blocks in windows

The weight of the window has to be distributed over setting blocks in such a way that the frame carries the weight of the pane and additional, avoidable stresses caused by thermal loads and operation are ruled out. The pane itself may not perform any loadbearing function.

UV light-curing adhesive

This one-part adhesive cures when exposed to UV radiation (wavelength: 315–400 nm) and after curing is as clear as glass, or at least highly transparent, and hard or elastic depending on the type of adhesive.

UV transmission

The portion of short-wave solar energy that passes through a glazing element.

UV transmittance

In the case of glazing, the permeability with respect to ultraviolet (UV) radiation according to DIN EN 410 is specified for the range of wavelengths from 280 to 380 nm.

vacuum bag laminating

A special method for producing laminated glass. The product is surrounded by a plastic sheet. While a high pressure prevails in the autoclave, the vacuum bag is also evacuated. This prevents the formation of air bubbles in the region of the interlayer(s) in complex laminated glass products.

vacuum bagging

sedak carries out the lamination process using the so-called vacuum bagging method. This is associated with tight tolerances, high-quality edge finishes and a reduction in the risk of delamination.

vacuum hand suction cups

These are used for transporting panes of glass manually over short distances or as an aid during glazing erection. A spring- or lever-operated mechanism ensures that a vacuum is generated at the face of the cup. Safe working loads of up to 100 kg are possible.

vacuum insulation panel

This is a thermal insulation product (abbreviated to VIP) that which exploits the principle of the insulating effect of a vacuum. A VIP consist of a porous core enclosed by an impervious material that prevents gas or air infiltrating the insulating material.

vacuum lifter

Panes of glass can be installed with the help of a vacuum lifter. This is done by creating a vacuum between the suction cup(s) and the flat surface of the glass, which fixes the lifter to the glass so that it can be lifted and transported. Depending on their design, vacuum lifters can carry several tonnes and can be rotated or tilted as required.

vacuum lifting system

This is a group of several individual suction cups fitted to a frame and interconnected to form a more powerful lifting device. In most cases the individual suction cups are controlled via a multi-circuit system in order to reduce the risk of individual failures. Safe working loads of up to several tonnes can be achieved in this way so that even large, heavy glass elements can be processed and erected.


A sloping linear intersection between two roof surfaces that slope upwards from this line.

valley roof

A pitched roof form in which the two roof surfaces meet at an internal valley. The opposite of a gable roof.


This is a chemical element which is added to steel to increase its tensile strength, yield stress and heat resistance, and reduce its temper embrittlement. Vanadium achieves a fine-grained microstructure and makes steel insensitive to overheating.

vapour barrier

A vapour barrier is a membrane that is attached to the warm side of a component (usually the inside) to prevent the diffusion of water vapour. It is intended to prevent water vapour saturating the layer of thermal insulation and can act as an airtight (windproof) membrane at the same time.

vapour barrier

This regulates the infiltration of vapour (in the air) into building components and therefore prevents their saturation. The humidity of the air is heavily dependent on temperature. In Central European latitudes, the moisture difference is greatest in winter and therefore a vapour barrier is always attached to the warm (interior) side of a construction.

vapour deposition

Coatings of silver, tin or indium can be applied to the surface of the glass using this method in order to produce low E or solar-control glasses.

vapour diffusion resistance factor

This designates a material’s specific resistance to water vapour (in the air). The lower the value, the easier it is for vapour to infiltrate the material. Multiplying this factor by the thickness of the component results in the equivalent air layer thickness (sd-value).


The Verband der Elektrotechnik, Elektronik und Informationstechnik e.V. (Association for Electrical, Electronic & Information Technologies) is one of the largest technical and scientific bodies in Europe.


The Verein Deutscher Ingenieure (Association of German Engineers) is a body representing the interests of engineers and natural scientists in Germany.

vehicle glass

The general term for the types of glass used in vehicles, e.g. laminated safety glass or toughened safety glass.

ventilation louvres

Usually electrically operated façade elements that regulate the flow of air through a component or façade.

vernier calliper

This is a tool for measuring internal and external dimensions. Analogue and digital versions are available. Their main use is in metalworking.

vertical glazing

This is glazing that is installed essentially perpendicular to the level of its surroundings. The glazing is still classed as vertical glazing even if its angle deviates from the vertical by up to 15° (the actual angle depends on the particular regulations).

vibration damper

Structures or parts thereof that are sensitive to vibration can be protected against damaging effects by installing vibration dampers. Vibrations can be caused by people, wind or earthquakes. Especially lightweight facade designs may be susceptible to vibrations and in such cases it may be necessary to install vibration dampers.

Vickers hardness

Named after the British aircraft manufacturer Vickers, this hardness test is used for hard materials with a consistent composition, but also for thin-wall workpieces or those with a hardened surface and perimeter zones. It is very similar to the Brinell hardness.

Vierendeel girder

A frame system in which the top and bottom chords are linked by vertical members only, with rigid connections.


This is a measure of the internal resistance to flow of a substance (usually a fluid).

visible light

That part of the electromagnetic spectrum, with wavelengths from 380 to 780 nm, that is visible to the human eye.

visual mock-up

This is a model made for demonstration purposes, to obtain an impression of the visual effect only.

visual quality zone

We divide a pane of glass into main, edge and rebate zones in order to assess its visual quality. Only minor optical impairments are permitted in the main zone.


The German Vergabe- und Vertragsordnung für Bauleistungen (VOB, Construction Contract Procedures) contains rules for the award of building contracts by public-sector clients and also the content of such contracts. The VOB is divided into three parts: general provisions for the award of contracts (VOB/A), general contractual conditions for the execution of construction contracts (VOB/B) and general technical specifications in construction contracts (VOB/C).


The unit of electric voltage.


German abbreviation for laminated safety glass (Verbundsicherheitsglas). VSG consists of a least two panes of glass and an interlayer, which is usually in the form of a tear-resistant polyvinyl butyral sheet (PVB; sheet thickness ? 0.38 mm). If one or both of the panes are broken, the fragments continue to adhere to the PVB.

Waldglas, forest glass

This was a green-tinted potash glass. The greenish covering was due to the iron oxide in the quartz sand used.

walk line

This is the imaginary line followed when using a stair. It begins at the nosing of the first step, is in the middle of the stair width and ends at the nosing of the last step.

wall tie

Usually a small bar-type component, loaded in tension, for fixing components together. Wall ties are used to tie together the leaves of masonry cavity walls.

Wallner lines

Wallner lines or ridges at the edge of the glass are caused when glass is broken. With a clean break, they should run evenly and rounded over the broken edge.

warm edge

The designation for an insulating glass spacer with improved thermal properties.

warm façade

This is a single-leaf façade made up of layers of the same or different materials. This single-leaf façade construction performs the weatherproofing and thermal insulation functions.

Wärmedurchgangskoeffizient U

see 3

warp and weft

In membrane constructions the method of manufacture results in a difference between the warp and weft directions. The warp direction is parallel to the length of the material, the weft direction at 90° to this, i.e. transverse to the roll of material. Most membranes are less stiff in the weft direction than in the warp direction. These two primary directions are a result of the weaving process.

water glass

A water-soluble glass (sodium silicate) that is an intermediate product for sol-gel processes.

water jet test

A special nozzle is directed at the joint in a façade for spraying with a specific pressure from a certain distance. No water may infiltrate the joint in this test.

water vapour diffusion resistance

This specifies to what degree water vapour can penetrate an insulating material. This is important for the use of an insulating material in addition to its ability to absorb or repel water.

water-jet cutting

Complex glass geometries can be produced with a help of a water jet. The cut edges have a matt, slightly roughened surface. Toughened safety glass cannot be cut with a water jet because it would be totally destroyed.

watt-hour (Wh)

This is one unit of work done or energy. 1 Wh corresponds to the amount of energy expended or consumed in 1 h by a machine with a power of 1 W.

weatherstripping, weatherproofing

This consists of barriers to wind and rain. Should rainwater nevertheless infiltrate the junction between window and adjoining component, it must be able to drain away directly to the outside in a controlled manner. It must also be guaranteed that moisture from inside the building infiltrating the weatherstripping zone can escape to the outside.


Weight is the force exerted by a body due to the force of gravity acting on its mass. Weight is used instead of mass in structural calculations especially.

weld seam

The interface between two workpiece edges connected by welding.

weld seam bending test

This test according to DIN 50111 (standard now withdrawn) is used to assess the deformation capacity of welded connections. The different (material) areas of weld seam, heat affected zone (HAZ) and parent metal are checked separately in succession for their deformation capacities.


This describes the property of being able to create a material bond between components by means of a welding-type procedure. The weldability of a component depends on how suitable the material is for welding, whether the assembly is accessible for welding and whether the functionality of the assembly is still guaranteed after welding.

weldability of steel

This describes whether a steel is suitable or unsuitable for welding processes. Unalloyed and low-alloy steels with a low carbon content are readily weldable. However, even high-alloy steels and aluminium and copper alloys can still be welded using special methods.

weldability, welding suitability

This is the ability of a material to form a permanent connection between itself and the same material or a different material by means of welding.

welded glass fixing

Such fixings are used when pane weights are so great that aluminium glass fixings are no longer adequate. Flat materials are used. The width must match the thickness of the pane. They are welded all round according to structural requirements. The thickness of seals and thermal breaks must be taken into account.

welded pipe

The raw material is either strip or sheet steel. We distinguish between two forms: longitudinal welded and spiral welded.


The permanent jointing of workpieces and components by means of heat or pressure. In fusion welding the parent materials are heated until they liquefy and can then be joined together.

welding distortion

This occurs as welded parts cool and is particularly problematic in the case of long weld seams and thin-wall components. Designing with welding in mind helps to avoid or at least minimise this problem.

welding procedure test

Welding parameters and welding conditions are monitored during the production of a test weld. The test piece is then subjected to extensive non-destructive and destructive testing. If the results are positive, all welding parameters are recorded in a report (WPQR, welding procedure qualification record). This then serves as the basis for the final welding instructions.

white flashed glass

A colourless base glass with a milky flashed layer for producing a diffuse light that reduces shadows.

white rust

A form of corrosion that affects zinc surfaces under certain conditions.

wide-flange beam

A steel beam section used in structural steelwork, e.g. in single-storey sheds, bridges, industrial and commercial buildings.

wind load

The wind pressure and suction forces acting on a structure or part thereof. This load is critical for the design of façade assemblies and their components. It is either specified in the tender documents or a reference is made to relevant standards.

wind load factor

This factor is calculated from the pressure specified in Austrian standard ÖNORM B 1991-1-4 and the position of the glazing in the façade.

wind speed indicator, anemometer

A device for measuring the speed of the wind. In the case of a high wind speed it indicates when louvres should be raised or awnings retracted.

wind survey

A report that specifies or verifies the wind loads to be expected for a construction project.


A window is an opening in a wall, usually an external wall of a building. Its purpose is to allow light and/or air into the interior of the building and permit a view into and/or out of the building.

window handle

A piece of window hardware used for opening and/or unlocking a window.

window hardware

Various items that connect the movable part of a window, the opening light, to the fixed part, the window frame. Various types of hardware are available to suit the way in which the window is intended to be opened, e.g. fittings for side-hung, tilt-and-turn, sliding windows, etc.

window lintel

The part of a window (or door) opening that forms the upper boundary to the opening. Lintels can be made from a variety of materials (timber, steel, reinforced concrete, masonry). Prefabricated lintels are frequently used in masonry walls. These are usually elements reinforced with round steel bars.

window safety mechanism

On a tilt-and-turn window, this device prevents the opening light being switched from the tilt to the turn position or vice versa when actuating the handle with the window open.


This is a product with, usually, a circular cross-section. Billets are hot-rolled to produce wire rods, which are wound into a helical form after passing through the roll stand. If thin wires are required (< 5 mm dia.), the diameter is further reduced by way of cold-forming in drawing plants.

wire rope

A rope made from individual strands of steel laid (i.e. twisted) together. The lay of a wire rope is determined by the stranding machine, where the individual wires are passed through holes in a plate. The plate is rotated to create a wire rope from the individual wires. Often colloquially referred to as (steel) cable.

wire rope

A rope whose individual strands are made from steel instead of fibres.

wire rope clamp

A screwed or bolted connection for – in most cases – steel wire ropes.

wired glass

Wired glass is a polished glass with a welded wire mesh inlay. Subsequent working after rolling gives the glass essentially flat surfaces and the view through is practically undistorted. It belongs to the group of safety glasses; upon breakage, no fragments of glass can fall out of the frame.

work platform

A work platform enables work (e.g. maintenance, cleaning, painting, roofing, etc.) to be carried out on components above ground or floor level that would otherwise be inaccessible.

x-ray weld inspection

A non-destructive means of examining weld seams. The high-energy radiation penetrates solid bodies essentially in a straight line. This reveals the typical defects of weld seams: cracks, cavities, inclusions, undercut, lack of fusion, misalignment, incomplete penetration, etc.


A noble gas that is used to improve the U-value of insulating glass.

yield stress, yield point Re

This is the stress at which yielding starts to take place without an increase in the applied stress. If there is a drop in the stress at the onset of yielding, the material exhibits an upper and a lower yield stress, ReH and ReL respectively.

Z grade

Steel products with improved deformation properties according to DIN EN 10164 must be used for plates loaded perpendicular to their plane. Specially produced specimens are subjected to tensile tests perpendicular to the plane of the material in order to determine the Z grade. Grades: Z15, Z25, Z35.

zinc flake coating

A coating for protecting bulk components (fasteners, small parts) against corrosion which is applied by means of an immersion or dip-spinning process. The base coat consists of layers of zinc and aluminium. The zinc assures cathodic corrosion protection. Dry-film lubricants can be incorporated into the top coat.

zinc metal spraying

In this galvanising method a zinc wire is melted by a flame or electric arc and applied to the workpiece in atomised form with the help of compressed air. The zinc forms a porous layer on the workpiece while it is still in liquid form and exhibits good corrosion protection properties.

zinc-rich paint

A special type of paint that prevents corrosion. Zinc-rich paint is applied to surfaces – by brushing or spraying – when hot-dip galvanising of those surfaces is not possible for technical or aesthetic reasons.


Electrogalvanised sheet steel.