The new roof structure of the Grand Hall has been developed using an innovative truss system.
The acoustic performance of the space has been significantly enhanced using additional sound insulation materials adding substantial load in comparison to the original roof. A structural bearing, usually found in larger civil construction, was introduced to allow sufficient movement at the base of the truss before loading the restored masonry buttresses (which previously resisted the load from the original trusses). The allowable movement was calculated to ensure the same force acted on the masonry buttress as the original roof construction.
Preserving the original character of the roof was particularly important for the new design, and the original profile of the ceiling was carefully replicated to provide the template for the new system. A maintenance walkway has been provided, which dictated the width of the truss, and the depth has been designed to match the original geometry as closely as possible.