The development, on the site of a disused leadworks, includes a cinema, a threestorey exhibition space and a botanical house with a roof of inflated ETFE cushions. The exhibition space is a 'black box' environment with cast in-situ waffle-slab floors which are supported internally on a concrete frame and at the perimeter on solid 215mm brickwork walls bonded with hydrated lime/cement mortar.
The roof is used as a public garden/terrace and has a planted parapet. The botanical house is a lower building abutting the southfacing brickwork wall of the exhibition space. Humid air from the botanical house is discharged through this wall; it is drawn through meshed screens into a series of blockwork chimneys set against the inner face of the brickwork, passing out through louvred grilles above the cushion roof.
The ETFE foil roof cushions are retained at their edges by aluminium extrusions which run from wall to ridge. A pair of pre-tensioned 16mm diameter cables slide through each extrusion to support the cushions while accomodating movement caused by wind or thermal expansion.
A series of precast concrete 'nodes', faced with 365 x 300mm steel plates, are set in the brickwork of the south wall to support the cables; the nodes are stitched back to cast in-situ concrete plinths inside the chimneys.
A steel bracket, bolted to each plate, provides a fixing point for a pair of cables and also supports a gutter, a 300 x 100mm PFC channel. The cushions are connected at the outer flange of the gutter to a sliding purlin which allows movement and is sealed by a single-layer waterproof membrane.