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Joseph Aloysius Hansom’s 1834 masterpiece, Birmingham Town Hall, has been restored to its former glory. The £34m refurbishment, led by contractor Wates for Birmingham council, was completed in September.

Glazing manufacturer Selectaglaze was appointed in November 2005. The council wanted to keep the original restored windows, so Selectaglaze worked with Wates to create a secondary glazing system that helps block out traffic noise.

Selectaglaze operations director Keith Mercer explains how the contractor and the specialist installed 28 windows, each weighing 200kg, at a height of 8m above the ground.

Keith Mercer
Operations director, Selectaglaze

Q: What was the client’s brief?

A: The client was keen to retain the primary windows because they were the last remaining parts of the original building. The windows were very tall, with a casement of 4.5 × 1.8m, set 8m off the floor at the balustrade level. Also, they had to perform really well acoustically.

Q: What did you think when you were presented with the requirements?

A: We were shocked. We had the right product for the acoustic performance, but we were worried about whether we’d be able to make them in such a large size and put them into place. That was an awkward situation.

There were also a lot of restrictions on site because we had to work around the auditorium circle, seats and balcony.

Q: How was the design developed?

A: Tests on the acoustic performance of our windows suggested that, combined with the existing windows, sound could be cut by 49dB. We won the contract in November 2005 and in December, we had a sample to prove we could produce single-glazed windows and a secondary glazing aluminium frame in the required size. We worked with Wates to make sure the structure would be able to take the weight. For this, hardwood timber was fixed on the side of the structure. We also modified the locking mechanism from two handles to one, because the platform couldn’t have two handles at that height.

Q: What were the main issues with manufacture and installation?

A: The windows were fully fabricated by Selectaglaze and fixed in the factory. We wanted to be sure everything was in place and have complete control over the process. The most worrying aspect of the project was to get the windows up into the wall. We worked closely with Wates and designed a special scaffolding system.

Q: How did you install the 200kg windows?

A: We put some rollers at the back of the vehicle and then used purpose-built ramps with rollers to carry the windows. They were then picked up from the floor on their sides, lifted on to the scaffolding, put back on rollers around the perimeter, lifted up into position, rotated in the air and fixed into the opening of the wall.

Q: What’s your opinion of the finished result?

A: It looks fantastic, but the key element is really how we worked with Wates to get our windows into place.