seele realised the Apple Cube for the Apple Retail Store on 5th Avenue, New York, USA, designed by Foster + Parnters.

500sqm

façade and roof

10.3 x 3.3m

panes

42

stainless steel steps

apple retail store 5th avenue new york

The Apple Retail Store on New York’s 5th Avenue was rebuilt for the third time. Once again, façade construction specialist seele was appointed to design and build the all-glass envelope of the “Apple Cube” with a total area of about 500sqm. The glass cube was built exactly as before, with 15 panes of glass, eight glass fins and four glass beams carrying the roof. But the spiral staircase is being completely replaced because the basement has been lowered to increase the clear height in the subterranean retail area.

  • The architects from Foster + Partners have redesigned the stairs. Instead of the all-glass staircase in the existing store, they proposed a minimalistic mirror-finish stainless steel construction with integral lift. seele has provided a central steel structure, the “drum”, to achieve this complex staircase design. Sheet steel annular segments, cut with water jets, provide the shape. These are welded to vertical hollow steel sections to create a 10m high cylindrical framework with an outside diameter of 3m and a weight of almost 12t. The cladding on the outside of the drum is made from stainless steel panels with a mirror finish. Running in the centre of the steel structure is the lift linking the entrance level with the retail area underground. The lift car has a backlit satin-finish glass floor, a clear glass roof and etched glass walls.

  • The glass cube was built exactly as before, with 15 panes of glass, eight glass fins and four glass beams carrying the roof.
  • The Apple Retail Store on New York’s 5th Avenue was rebuilt for the third time by façade construction specialist seele.
  • seele installed a minimalistic mirror-finish stainless steel construction with integral lift.
The glass cube was built exactly as before, with 15 panes of glass, eight glass fins and four glass beams carrying the roof.
The Apple Retail Store on New York’s 5th Avenue was rebuilt for the third time by façade construction specialist seele.
seele installed a minimalistic mirror-finish stainless steel construction with integral lift.

seele realized the complex geometry of the staircase

Particularly challenging here was the complex geometry of the cantilevering treads, which seem to float in mid-air yet hold the curving glass stringer in place. The design previewed just one point fixing per tread. seele achieved this by using the handrail to connect the individual panes of the glass stringer together, which stabilises them, and carry the ensuing lateral loads on the handrail by way of its radial geometry. In order to prevent the entire staircase from vibrating, a rigid design was necessary, with sturdy connections to the drum.

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    Each tread consists of a loadbearing frame surrounding a flush-fitting interchangeable stair tread with grooved upper surface. The underside of each tread consists of a twisted mirror-finish stainless steel plate. The torsionally rigid “backbone” for the tread, fixed to the drum, is made from a 130mm diameter bar in high-strength stainless steel turned down to a tapered form and welded to milled free-form solid section to form a frame. The entire surface was then milled and fine-finished on five-axis machining centres before being polished by hand in many stages from coarse to fine in order to achieve a mirror finish.
Due to a tight schedule, the Cube had to be installed before the stair construction, except for the middle roof glass panel. The drum was then lowered downwards through the opening in millimetre work, with only 75mm clearance on all sides.
With its mirror polished undersides of the steps, the design of the staircase reminds of an aircraft turbine.
The exchangeable step surfaces are integrated flush into the step frames with milled grooves.

Credits

Client Apple, Inc.
Architect Foster + Partners
Engineer Eckersley O’Callaghan
Date of completion 2019
Scope of seele supply
  • Glass Cube
    • Approx. 500sqm facade and roof, consisting of 15 glass panes (heat strengthened glass and toughened safety glass 3 x 12mm) with a size of 10.3 x 3.3m each and 8 glass fins as well as 4 glass beams
    • double-leaf glass swing door with glass canopy
  • Staircase
    • glass stringer 3 x 12mm, consisting of 15 chemically toughened glass panes
    • 42 stainless steel steps and two landings
  • Elevator
    • Steel construction with stainless steel cladding, mirror polished
    • Cabin with steel-glass construction, side panes made of etched glass, floor made of stainless steel with inserted etched glass, upper pane transparent