The structure in detail: 12,000 rectangular sections with very few support points combine through 7,000 or so nodes to form a delicate grid. Geometrically, the shell structure is based on a grid of equilateral triangles. The nodes of the roof shell sit at different heights on the standard structure of this grid network, and virtually no triangle or node is identical. Grids like this are typically welded together on-site. For the London arcade, however, the complete roof structure was delivered ready to assemble and bolted into place. The accuracy required in the length of the lattice struts of 2/10mm corresponds to a tolerance standard that is typical in engineering. The thickness of the struts varies depending on the structural requirements. This design kept the outer cross-section profile consistent, producing a precise, uniformly sized grid.
All the nodes are unique. They are composed of 20 individual parts that are welded together and precisely milled for angle and size on a CNC milling machine. 60% of the surface consists of thermal insulation panels, and the remaining area is double-glazed. The roof panels are arranged so that the glazed areas are shaded when the sun is low. The triangular roof panels are placed on the grid structure with sealing strips, clamped with two point fittings on each side and wet-jointed.