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Birmingham鈥檚 Fort Dunlop sums up what Urban Splash is all about. The unconventional developer takes on tough urban regeneration projects and through them breathes new life into workplaces and communities.

A local icon, Fort Dunlop is undergoing a radical 拢40m overhaul, which will transform it from a crumbling disused tyre factory into a mixed development of offices, retail and leisure space, linked to a new 100-bedroom hotel. Fundamental to the redesign were plans to retain the building鈥檚 large industrial scale and to emphasise this through a series of large, simply expressed architectural forms.

Built in 1917, the Dunlop Tyres HQ was at one point the world鈥檚 largest factory and by 1950 was home to 10,000 workers. The tyres produced there have, among other things, helped set two world land speed records, had a hand in 66 Formula One victories and even done their bit during the Battle of Britain, having been fitted on numerous fighter planes and bombers. It has been closed since 1980.

鈥榃e were impressed with the sheer industrial scale of the building, which we wanted to preserve and also emphasise through various new features,鈥� says the scheme鈥檚 architect, Hazel Rounding of Shedkm. These features include huge continuous glazing panels, the UK鈥檚 largest green roof, a giant Hollywood-style sign and two of the largest lobby entrance doors ever installed in the UK.

The doors will be used by 3,000 people entering and leaving the building morning and night, and they not only had to reflect the grand scale of the scheme, but at the same time take into account disability regulations and limit heat loss. The architect鈥檚 solution had several door manufacturers saying 鈥榠t can鈥檛 be done鈥�, before Geze took up the challenge.

鈥楾he Geze main entrance doors 鈥� one at the front and one at the rear of the building 鈥� were vital to our plans for pedestrian circulation,鈥� says Rounding. 鈥楨veryone will be drawn into the building鈥檚 central atrium through them, and from there they can filter through to the rest of the building via four cores of lifts and stairs.鈥�

From the outset the specification of the doors posed problems. In the summer, shedkm wanted them open constantly, but in the winter they would have to provide a draft lobby to prevent heat from escaping. Meanwhile, legislation covering disabled access and emergency exits had to be observed. 鈥楾he building is all about big, bold clean moves, but with all these factors to consider we began fighting with the idea of installing lots of individual doors,鈥� says Rounding.

A large revolving door solution was initially proposed coupled with swing doors on either side to comply with the Disability Discrimination Act (DDA). 鈥楤ut we had this situation where we were trying to incorporate 2.1m-high doors into an elevation of very large glazing panels 鈥� it just wasn鈥檛 going to work,鈥� she recalls.

Her solution was two huge drum-shaped sliding lobby doors. This would remove the need for separate DDA-standard doors and, linked to the fire alarm, the doors could automatically sweep open to allow easy escape, unlike revolving doors.

鈥極nce we鈥檇 settled on the sliding drum door design we wanted to push the boundaries of how large we could make it,鈥� says Rounding. 鈥楾he building has a 5m-wide column spacing, so we specified a door that could occupy that space. We spoke to several manufacturers, whose reaction was basically: 鈥渢hat鈥檚 too big, we can鈥檛 do that, you鈥檇 have to install extra doors鈥�. But Geze came up with a workable solution.鈥�

We spoke to several manufacturers whose reaction was: 鈥榯hat鈥檚 too big, we can鈥檛 do that鈥�

Hazel Rounding, Shedkm

Geze鈥檚 UK specification manager Paul Wyatt explains how the doors work: 鈥榃hen there鈥檚 a constant stream of people coming through they stay open, but during the rest of the day, when there鈥檚 more single traffic, they function like an airlock.鈥�

Each drum has two sets of sliding doors positioned 4m apart. When someone passes through the centre of the drum the set of doors behind begins to close as the set in front opens, creating a draft lobby. An air curtain inside the drum also ensures that it鈥檚 slightly pressurised. 鈥楶rovided the doors aren鈥檛 open for too long it鈥檚 a way of preventing air loss,鈥� adds Wyatt. Interestingly, the wider the diameter of the drum, the more effective it is as a draft lobby.

Frank Walsh is construction manager for Urban Splash Build, which has been on site since July 2003. He鈥檚 loving every minute: 鈥業 still get butterflies every morning when I drive towards the building,鈥� he chimes.

When the doors came to be installed last September he had three men working on it, alongside three from Geze. 鈥業t was a tricky installation, it really was,鈥� says Walsh. 鈥楾he timing of it was critical for the initial opening in December. It took about three days to install each one,鈥� he says. 鈥楾he drum itself is freestanding and isn鈥檛 tied back to any of the structure. We created an opening for it, which we reinforced with a steel goalpost structure to support the large glazing panels above.鈥�

Shedkm wanted to preserve the building鈥檚 original ceiling soffits and columns, so each floor is raised to provide room underneath for heating, condensers and other services. In the door zones that space was used to install a concrete load-supporting upstand with steel rings cast into it for the drum doors.

Unfortunately, when CM visited the site the doors weren鈥檛 functioning properly, with the inner doors held open. However, Rounding assured us that this was because they still had to be linked into the building management system, which would be completed before March.

If you鈥檙e planning a similar job, Walsh has a few tips: 鈥楳eet with your supplier regularly, communication is paramount. With bespoke items like this it鈥檚 also vital that the specialist knows what they鈥檙e doing. Some suppliers on this job weren鈥檛 up to scratch, but I had no problems with Geze.鈥�

Rounding is happy with the results too: 鈥楢lthough the doors are not working at full capacity yet, we鈥檝e had a few events here with 3,000-odd people and there were no problems. Ultimately I think we managed to marry the form with function, which as an architect is very satisfying.

鈥楾he system provides the draft exclusion advantages of a revolving door, the grand aesthetic we were after, plus a large opening in the facade to get people out fast in an emergency,鈥� she adds.

With the final floors currently being fitted out, work on Fort Dunlop is scheduled for completion in March 2008.