The complete renovation of Birmingham Town Hall, a Grade 1 Listed landmark, was a huge undertaking by any standards. Concerns about the safety of the structure ruled out conventional methods of scaffold and temporary roof construction and presented many challenges - the main being how to fully enclose the building with scaffolding, enabling restoration work to continue on all faces, plus the roof, simultaneously.
Wates Construction and Stanford Scaffolding worked with HAKI continually during the design phase to develop a HAKITEC 750 temporary roof solution that met the complex demands of the project.
The main aim was to reduce the load imposed onto the building. The final design by HAKI avoided tying back into the main structure as much as possible because the forces transferred to the building could potentially have been too great to withstand.
As there was no room for sections of the roof to be pre-built on the ground and craned into position, the roll-out method devised by HAKI was employed which meant that the system could be erected from a safe working platform at one end of the building and progressively rolled out into place.
The roof featured 34 separate 'bays' allowing six new prefabricated steel roof trusses, each weighing 3.6 tonnes, 21m long by 1.5m wide, to be lowered into the Hall at varying intervals.
Says Paul Greaves, Project Manager for Wates Construction: "Protecting the precious nature of both the internal and external fabric of the Town Hall was central to the specification of the temporary roof. As the main contractor, we had to have complete confidence that the roof's design and construction could fulfil a rather abnormal set of conditions."
- Planned access into the roof space. The open sections of the temporary roof could be closed in just 15 minutes to protect the Hall's ornate ceilings and organ against rain and snow.
- Mix of 1.25m and 2.5m wide bays allowed the wider bays to line up exactly with original oak beams, allowing new lighting gantry trusses to be craned in.
- Complete roof built using the "roll out" method to ensure total safety during erection.
- Clear span of 33.2m and length of 62.5m achieved.