Haki International

HAKI Keeps Prestigious Town Hall Renovation under Safe Wraps
Release Date: October 2005

Birmingham's Grade 1 listed landmark Town Hall, currently undergoing extensive renovation work, is being kept under safe wraps by a unique HAKITEC 750 Temporary Roof. The repairs, alterations and improvements to the building, which was first opened in 1834 and styled on the Roman Temple of Castor and Pollux, will cost around £34 million and are being funded by a Heritage Lottery Fund grant, Birmingham's City Council and a European Regional Development Fund grant.

The Town Hall is owned by Birmingham City Council and is steeped in colourful history. A public speaking venue for Prime Ministers and politicians; home to the CBSO; host to performances by Mendelssohn, Edward Elgar, Yehudi Menuhin and a wide variety of international music and other events through the decades, the building was closed in 1996 due to concerns about the safety of its structure.

Today, the renovation programme in progress will put Birmingham's Town Hall firmly back on the world stage as a leading performance venue. Specifically designed to harness the aspirations of the community, different cultures and age groups, the revived Town Hall will blend the best of modern acoustic technology, performance facilities and audience comfort whilst retaining much of the building's historic past.

But balancing old and new has posed some challenges for the project's main contractor Wates Construction. Not least how to fully enclose the building with scaffolding to allow work to continue on all faces whilst restoration work is undertaken on the roof, which consists of substantial structural repairs and eventually new lead covering per the original construction.

Building for the Future

Because of the age of the Town Hall and concerns about the safety of the structure, conventional methods of scaffolding construction and temporary roof erection have not been practical. It has been essential to avoid tying back into the main structure as much as possible because the forces transferred into the building would potentially be too great for it to withstand.

Wates Construction therefore needed to team up with other specialist contractors to devise a workable yet safe solution.

As one of several temporary roof specialists invited to tender, HAKI Ltd's design and development team set about finding a solution to a rather unusual problem. What soon became apparent was that the scaffolding and temporary roof would need to become an integrated structure. Which meant that the design of the roof would become the controlling factor so as to reduce the loads applied to the building by transmitting them through the scaffolding.

But other design criteria also had to be met. With the removal of the old roof six new steel trusses to house state of the art lighting, acoustic equipment and walkways needed to be lowered through the temporary roof to support the Town Hall's original oak beam roof trusses at varying intervals. To allow each of the new prefabricated units weighing 3.6 tonnes, 21 metres long and 1.5 metres wide the roof therefore needed to be able to be opened in individual sections.

Under the Weather

A final consideration in the temporary roof design was the speed at which it could be opened and closed. Not only to crane in the new roof trusses, but also to protect the Town Hall's ornate ceilings and organ - once the biggest in the UK and today with 6000 pipes still larger than most cathedral organs - against sudden rain and snow. The maximum time it could take to close was 15 minutes.

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".

The HAKITEC 750 Temporary Roof - Safe for a Rainy Day

HAKI's 750 roof proved that it could overcome the concerns about loads on the building's structure. By working closely with Wates Construction and appointed scaffolding contractors Stanford Scaffolding, the roof's design incorporated a mix of 18 bays 1.25 metres wide and 16 bays 2.5 metres wide, had a clear span of 33.2 metres and length of 62.5 metres. The wider bay trusses lined up exactly with the position of the original oak beams to allow pre-fabricated metal trusses to be craned into final position.

HAKI's Managing Director Paul Brunt comments, "Designing a temporary roof for the Town Hall project was particularly challenging. During the design phase we continually worked to reduce the load that would go back into the building and in fact our initial rolling roof design was abandoned during the pre-assembly phase as we established that the forces were not at predictable points. That's why even before we were awarded the contract for the HAKITEC 750 we elected to pre-erect a section of the roof to actual size at our dedicated Training Centre so that we could confidently demonstrate our proposed solution."

The unique HAKITRAK sheeting system was selected to open and close sections of the roof as needed. As a manually operated track system, HAKI proved to Wates and Stanford that an open section could be closed in just a few minutes in the event of bad weather and also that by opening sections one at a time, the lacing frames could be safely removed to crane in the new beams.

Raising the Roof

Not only was the pre-erected replica roof section useful for demonstration purposes, but it was also used to train Stanford's scaffolders to become fully conversant with the system before work commenced on site.

The HAKITEC 750 roof was safely erected in sections which were progressively rolled into position from a safe boarded and guard railed scaffold at one gable end. Collective Fall Prevention was achieved at all times.

On choosing the HAKI roof Wates' Paul Greaves said, "HAKI's commitment to proving that the HAKITEC 750 had been designed and tested for all possible problems through the trial erection and the fact that it was supported by safe erection procedures, all at the pre-contract stage, meant that we could be fully confident that the HAKI solution would meet each of the design criteria we needed to fulfil. What's more Wates Construction, Stanford Scaffolding and HAKI worked together as a close knit team to successfully locate the new trusses whilst protecting Birmingham's premier landmark at all times."

The HAKITEC roof system will remain in place until approximately the end of 2005.