Working details A GLASS ROOF
The glass roof of the National Glass Centre is 80m long, transmitting translucent light into the studios and galleries below. Visitors can walk on it. It is penetrated by a wind tower and two chimneys serving the glass- making furnaces on the floor below. Part of the roof is sheltered by a canopy of profiled steel.
The roof is supported by massive beams - their huge size reflects Sunderland's shipbuilding past. A series of 1750 x 400mm plate girders at 10m centres run 80m - from the entrance at one end of the building to the riverside at the other. Between the girders span 750 x 225mm universal beams; they have welded end-plates which are bolted to the webs of the girders, forming a series of 10m bays. The glass support structure, a grid of 100 x 100mm shss, is mounted on adjustable pedestals which rest on the top flanges of the grid of beams and girders.
The glass panels - most are 1235 x 1235mm square - comprise four layers of 8mm clear heat-strengthened glass laminated with pvb; the top surface is coated with a dot-matrix of slip-resistant ceramic frit. Each panel was silicone-bonded - by the manufacturer, Romag - to an aluminium frame and screwed to the shs support structure. The fixings allowed each panel to align with adjacent panels and with the 2.6degrees slope of the roof.
On the south side of the building, facing the river, the glass roof structure projects beyond the facade to shelter it from solar gain.
Visitors are protected by a balustrade at the roof edge. It consists of paired balusters bolted to brackets set in the webs of the universal beams; they support a balustrade of 30 x 30mm galvanised steel grillage panels, surmounted by a stainless-steel handrail.