Using the shell form as structure rather than cladding is a technology which Future Systems has transferred from boat-building to construct the new Media Centre at Lord's. The enclosure is an integrated structure and skin, highly engineered and entirely pre-fabricated.
The superstructure is a semi-monocoque resting on two concrete towers. It was made in two halves; the top half rests on bearings on top of the towers; the lower half is bracketed from a pair of concrete ring beams which run round the towers. When complete, the two halves act as one shell. Aluminium was chosen for the structure because it has a high strength/weight ratio, is malleable and can be welded as easily as steel, yet it needs no maintenance.
The architect drew a series of vertical and horizontal sections to define the final form. They were passed to Cornish boat-builder Pendennis. On computer the curved parts were flattened, a process called 'shell- expansion' - like peeling an orange and pushing it flat - so that the aluminium profiles could be plasma-cut to a flat shape.
The plates were then bent to shape by a computer-controlled machine and assembled on jigs into 26 sections, the largest, central section measuring 4.5m x 20m and weighing about 9 tonnes. When complete the sections were 'faired' and painted by Pendennis before transport to site.
On site a 'crash-deck' was built 1.5m below the building and a jig erected on it, on to which the sections were lowered. The shell was tack- welded, then welded in alternate sections. Once structural continuity was achieved the whole structure was de-propped.