Sound-insulated steelframed structures
The commentary boxes are mounted on the roofs of two staircases which give access to the seats. Each staircase enclosure is formed of rendered brickwork, with one side fully glazed with a steelframed window system.
The staircase glazing is restrained and the staircase roofs are each supported by a timber beam which spans between a 50mm diameter CHS and the rear brick wall.
To support the boxes, the architect has created a new structural frame based on a 152 x 152mm UC beam supported by a column bearing on the concrete beam tier structure one floor below. A series of stub beams welded to the UC support the framework of the boxes, pairs of 150 x 90mm parallel flange channels as floor and roof beams (PFCs) are welded to 100 x 100mm SHSs to form 'goalpost'portal frames. At floor level the channels are bolted to the original brick side wall with resin anchors.
At roof level the channels support 100 x 50mm timber joists.
As the boxes are only used in summer, thermal insulation was less important than sound reduction - to prevent airborne noise intruding on the live radio commentary.
The walls consist of a sandwich of plasterboard, mineral fibre insulation and marine ply on the outside to which the rainscreen cladding - timber weatherboarding, ply or profiled aluminium - is fixed.
The glass walls facing the pitch are made of a single sheet of 10.8mm laminated glass, strong enough to resist the force of the occasional cricket ball smashing against them.The corner edges are jointed with clear silicone.
The insulated roofs are covered with a Trocal singleply membrane and drain to the rear of the boxes.