working details: Steel lattice structure clad with aluminium
The centre is a single volume, more than 120m long and 35m wide, with an internal height of 7.5m. The structure is, in essence, a 'post and beam' construction of prismatic trusses. They run along the two side walls and the roof at 1.8m centres and are 2.4m deep, creating a 'double-skin system' which allows service zones, WCs, stores, small kitchen areas and other facilities to be incorporated within this depth.
The outer skin is formed of five different types of panel; the inner skin of fixed perforated louvres, laid horizontally.
The side-walls were assembled as a series of lattice towers; the lowest diagonals were omitted to make most effective use at ground level of space within the truss depth.
The roof trusses were pin and slip-jointed to the towers. To direct water run-off and to counteract the illusion of 'sag' in perfectly horizontal spans, the roof trusses were assembled with a slight entasis, arching upwards by 150mm. The trusses incorporate catwalks to allow maintenance of lighting and of the adjustable perforated louvres which run in bands below the trusses.
The original wall panels, 1,800 x 1,200mm, each comprised a 100mm thick core of phenolic foam bonded between ribbed silver anodised aluminium skins.
The panels were clipped on to a gridded sub-frame of Ushaped aluminium channels and the joint between adjacent panels was sealed with a neoprene gasket; the neoprene itself was jointed at the factory and on-site to form a continuous lattice over the structure.
In 1988, following the discovery of deterioration, the panels were replaced. The new ones have a honeycomb aluminium core with mineral fibre insulation and aluminium skin with white PVF2 finish.