Art of gold

Some call it the Yellow Banana. Others, the golden croissant. The taxi driver suggested it might be a white elephant.

For contractor Banner Arts, which is building Colchester’s new art gallery, the shape of this building is definitely the key factor: there’s not a horizontal or vertical line in site.

‘The building is 3D in every sense of the word,’ says Banner project manager Dave Moffet. The building follows the site’s rising gradient, has sides that slope outwards and a curved roof which varies in radius along its length. ‘Understanding what the architect wants in terms of the envelope of the building has been a challenge for the whole team.’

Particularly challenging has been working out how to wrap the strips of golden cladding material around the centre’s curvaceous form. If that isn’t enough, the whole project stands on an ancient Roman site, and archaeological considerations are paramount.

The architect responsible

for this distinctive building is Rafael Viñoly, a New York practice which has recently set up in the UK. The Colchester project, which it won through competition, is its second building in the UK to start on site – the first was a performing arts centre in Leicester.

The building will be the new home for Firstsite which was set up in 1993 to show contemporary art. Alongside artists such as Anthony Gormley and Louise Bourgeois, the University of Essex will exhibit its collection of Latin American Art, the biggest of its kind in Europe. The space will also house teaching l

l spaces and a restaurant. The East of England Development Agency, one of the project’s funders, hopes that the centre will kick-start the regeneration of the run-down St Boltolph area of Colchester in which it is situated.

Locals have been less than enthusiastic about the project. ‘It’s infamous,’ says my taxi driver when I ask if he knows where it is. Although Colchester Borough Council itself has contributed only a small part of the funding, residents are worried that they will have to foot the bill for running it if the predicted number of visitors don’t materialise.

Moffet has been working alongside the architect and engineers since April 2005, looking at logistics, buildability and tendering the bulk of the building, around 80% in cost terms. ‘That gives the client confidence that we will be within budget,’ says Moffett. ‘It shares some of the risk between contractor and client and allows the contractors to be on board much earlier.’

There have been technical challenges from top to bottom on this project. A major hurdle was the site itself: it is a scheduled ancient monument containing Roman ruins. This means that all excavation has to be supervised by an archaeologist: it wasn’t just a matter of whacking a few piles in.

The solution developed by the team means the building is supported on a raft foundation which sits on top of a metre of fill. This ensures that no point pressures are exerted on the underlying archaeology which, while experts don’t think it is of high interest, may tie up with other findings in the town, and must be preserved for future generations.

Archaeologists also excavated the trench which will bring services into site. They unearthed and logged part of a Roman town house and two streets.

The steel frame for the one-storey building, already in place, is a series of portal frames, albeit unusually shaped ones. The frame sits on a ring beam around the perimeter of the raft. Contractor SH Structures installed the 400 tonnes of steel within five weeks.

It’s quite an empirical exercise. we’re getting close now but we’ve struggled

Dave Moffet, Banner Arts

Aside from its shape, the building boasts a unique door. Its main entrance is through a glass wall beneath a canopy formed by the steel frame.

A 10m x 3m glass door will open up during the summer to encourage visitors in and also allow big bits of art in and out (see diagram).

This was an interesting item to tender for, with Banner choosing two firms with whom they did some design development. One proposed a mechanical system, the other pulleys and weights. ‘It was a difficult choice. They were both competent companies,’ says Moffet. ‘Whilst the cable system would have had factors of safety in it, we felt that it had a little bit more flexibility in it. We took a decision within the design team that the mechanical method seemed to be more acceptable.’ The winning firm is Eiffel UK.

Yes, that Eiffel.

Inside the building the raised floor, with a 450mm void to distribute services and air, is being laid and will have a powerfloat finish.

As with many of the internal finishes the flooring material has yet to be decided. Some materials have had to be reconsidered to keep within the final budget.

‘As usual the budget gets stretched and you have to look back at some materials,’ says Moffet. ‘We’ve been doing quite extensive value engineering since October, looking at things like the services and glazing finish.’ Although mostly naturally ventilated, some spaces require air conditioning because of the art. A high level skylight running along the North side of the building will bring natural light into the space.

The building’s cladding is striking not only because of its unique form. It will also be the first application of a golden sheeting material called Tecugold, which has previously only been used in tile form. It arrives in sheets in coils, rather like any standing seam roofing system, and is then passed through rollers to shape it. Although a thoroughly modern material, the gold/copper alloy sheeting, costing £10,000 a tonne, requires traditional skills to install it.

Just where to install it is the big problem, however. Moffet has employed a surveyor who has been working since Christmas to try to plot on the building’s exterior where the sheets must go to form a distinctive herringbone pattern either side of the gutters.

The first approach was to take co-ordinates from the architect’s 3D model and plot those on the building. But the as-built building, although within tolerances, is not in exactly the same position as the model; we are talking about points with a, y and z co-ordinates here. So the roofers will have to find a best fit line between those plotted. ‘It’s quite an empirical exercise,’ says Moffet. ‘There are all these different tolerances. We’re getting close now, but we have struggled since Christmas to get the setting out.’

It will be satisfying to finally crack it, says Moffet, although he muses that Joe Public will never appreciate how much work has gone into it when they see the finished article. Only mistakes stand out; perfection is expected.

It is an interesting job for Moffet with its combination of early involvement, the challenges of the foundation and even the conundrum of the curves. But the highlight for him has been showing round groups of school children, something he hasn’t done on previous jobs. ‘You just wouldn’t believe the sort of questions they ask,’ said Moffet. ‘They are really interested.’

The plan is that the kids, enthused during the construction phase, will encourage mum and dad to bring them along to see the finished article once it opens in April 2008. ‘And I would like to think that there will be one or two engineers or architects among them,’ says Moffet. With inspiration like this building, who knows what sort of structures that generation will design and construct?