The roof of the square-plan,single-storey factory comprises three shallow barrel vaults with a series of flat roofs set between them on both sides.
Each barrel-vault roof consists of a row of curved 686 x 254mm beams supported on 457 x 191mm ubs which run along the edges of the flat roofs; these beams rest in turn on 'trees' - rows of branched columns - which run below the flat roof zone.
Each tree comprises a cruciform steel column, 10m high, made of paired 762 x 267mm ubs. Four branch-like tapered beams are welded to the top of the column and are stiffened at the ends with 139mm-diameter chs posts, on which the barrel-vault roof structure rests.
The external walls are glazed at low level with dark grey pvf2-coated aluminium opening windows and clad with horizontally profiled pvf2-coated aluminium cladding.
The cladding panels are fixed to steel liner trays containing insulation which are fixed directly to windposts - a secondary cladding support system is not needed. At their heads the windposts - 457 x 191mm ucs at 7.2m centres - are bolted to the 139mm-diameter chs posts at the ends of the column branches which define a continuous strip of clerestory glazing.
A 457 x 191mm ub eaves beam runs along the tops of the chs posts and supports the flat-roof structure - a profiled steel deck on 305 x 102mm beams at 3.6m centres, covered with insulation and a single-ply roof membrane.
The eaves is defined by a parapet/coping in the form of a channel-shaped aluminium profile, reflecting the shape of the beam behind it. It is formed of three pressed aluminium components which were assembled on site and fixed to brackets reattached to the eaves beam.