09 May 2011

Bury St Edmunds multi-purpose hall is lined largely with American white oak

The new multi-function hall in Bury St Edmunds conceals acoustic and mechanical sophistication with a deliberately simple appearance and a restricted palette of materials.
Residents of Bury St Edmunds, a town in the east of England, now have a splendid new facility for classical and rock concerts, weddings, antiques fairs and a range of other functions. It will be obvious to anybody who attends several events that the hall is very flexible, since it can be configured with raked seating or an entirely flat floor. What will not be so readily apparent is that the interior of the hall, a harmonious space lined largely with American white oak (www.americanhardwood.org), is far less simple than it appears to be.
Set among the shops and flats of the new Arc development, the hall had to be acoustically isolated, and also offer its visitors a good aural experience.
‘When you go into the space, you have no idea how sophisticated it is,’ said Jim Greaves, the partner at Hopkins Architects in charge of the project. ’It feels very calm.’
Connoisseurs of concert spaces may also spot a similarity to the Snape Maltings concert hall in Aldeburgh, designed by Arup Associates in the 1960s. This is not coincidental – Snape has famously good acoustics, so echoing its form makes sense. Both have internal roofs that slope in both directions, with a relatively small flat element at the top. ‘It does all the acoustic reflection for us,’ said Greaves.
But although Snape and Bury St Edmunds are both in the east of England, their situations could not be more different. Whereas Snape is an isolated collection of former brewery buildings, the new hall is part of the redevelopment of a market town, on the site of a former cattle market. Hopkins designed the whole scheme, and deliberately placed the concert hall, called the Apex, between shops with flats above, so that it faced a new square. In this way, it prevents the square becoming a dead space at night, when the shops are shut.
Hopkins worked with theatre consultants Carr and Angier to work out the functionality that the auditorium needs to offer. ‘The business model works if there are four walls for hire,’ said Greaves, ‘which can operate with a flat floor or a rake.’ It can accommodate 1,000 standing or 500 sitting.
Structurally, it was necessary to make the enclosure very heavy, to prevent sound escaping and annoying nearby residents, particularly when the building is host to the ‘Battle of the Bands’, an annual rock concert. It therefore has a structural brickwork diaphragm wall, with a heavy concrete roof. The bricks, which are exposed on the walls of the concert hall, are handmade Charnwood Hampshire Red. The exposed headers have a special relief pattern, a kind of multiple star effect. This is handsome but also functional – it is part of the acoustic strategy to disperse reflections.
There are two levels of balcony, made of precast concrete, which cantilever from beams concealed within the diaphragm wall, and are tied back with large steel rods, also contained within the diaphragm wall. American white oak lines the roof, and forms the floor. It is also used on the fronts of the balconies and for the seating. It is a material with which Hopkins is familiar, having used it on the Haberdashers Hall in London and on the theatre at Emmanuel College, Cambridge. ‘I like it because it has a good colour and a good grain,’ says Greaves. ‘It’s consistent and good to work with, and you get a beautiful effect.
You tend to get a feeling of quarter-sawn timber from it, even if it hasn’t actually been cut that way. And it is kiln dried, so if the joiners know what they are doing, you don’t get a lot of fluctuations in moisture content.’
On both the floors and the roof, 18mm thick oak is fixed to a plywood backing of the same thickness. The acousticians at Threshold Acoustics decreed that both should be fixed resiliently so that they can absorb low frequency sound. The flat area at the top of the roof consists of a large rooflight, so that when the space is used for events such as weddings, daylight can penetrate. A blind is drawn across it for performances.
This is not the only element of the design that has been affected by acoustic considerations. There are openings in the balcony fronts to permit sound to pass through and make them less reflective. And the seating also has a role to play. This seating, designed by Luke Hughes and manufactured by Race, is both elegant and supremely functional. The fact that the floor can be converted from flat to raked means that the raised flooring all consists of ‘wagons’ – blocks with seating attached which can be stored away beneath the flat floor. The seats on the wagons are bench seats, in groups of two or four. This means that although each seat has its individual arms, they have level tops, so that looked at from both in front and behind they create a simple repeating rhythm. There are also tip-up seats on the balconies.
Hughes designed the seats in a mix of solid American white oak elements and veneer. ‘The great thing about American white oak is that it is consistent in its colour and tone, ‘ said Luke Hughes, ‘ and there is less waste than with European oak. More to the point in this instance is that it is consistent with the palette that the architect had chosen.’
Hughes has worked frequently with Hopkins before. ‘I think they have a very good understanding of timber and of how it behaves,’ he said. The continuing collaboration is important, he says, ‘because you have to get under the skin of how the architect likes to see their building and make it work for them.’
Equally important is making the seating work to a budget, and at Bury St Edmunds, as so often, money was tight. When Hughes talks about value engineering, he does not mean it in the debased sense of shaving costs and quality but of genuinely getting value for money. Part of this consists of knowing where to use solid timber and where to use veneer. But it also comes from a profound understanding of materials. For instance, the seats and backs are upholstered in leather, in an indefinable neutral brownish/greyish/purplish colour. ‘You have to work out the size of the leather,’ Hughes said, ‘and how to cut it to get the most out of a single hide.’
The upholstery has to be comfortable, but it also has to be designed for when nobody is sitting on it. In rehearsals, when the hall is empty, it is important that it behaves acoustically as nearly as possible to when it is occupied. This is achieved through the thickness and shape of the upholstery.
The seating uses very few elements – a simple steel structure, timber and leather. Durability is important, particular in a hall like this where the chairs will be moved around frequently on the wagons. ‘Leather is the toughest material you can get,’ Hughes says. Equally important is avoiding any elements of bespoke or contemporary ironmongery. If a chair is damaged and needs replacing in 15 or 30 years time, it is very likely that matching elements will no longer be available.
There is a similar economy of materials in the hall itself, and indeed one of the things that makes it so elegant is what one doesn’t see. Where are the building services, and, when there is no performances, where is all the rigging for the lighting etc? The visual absence of these elements enhances the feeling of calm, as all one sees are brick, concrete, wood and the stainless steel tie systems that holds together the roof. But it required some sleight of hand, and in fact added to the sophistication of the design.
‘There is no ducting,’ explained Greaves. ‘All the air moves through a plenum in the diaphragm wall.’ Fresh air comes in through small holes in the other side of the diaphragm wall, exposed in the foyer, and there are outlets from the plenum through some of the timber panelling at the base of the roof. This just appears to be a pattern of holes in the timber. All air extraction is at the top of the space.
Similarly there are no technical walkways within the volume of the hall. Instead they are contained within the void of the roof space. The rigging trusses are stored away, and suspended from a mechanism in the roof when needed.
The plan of the building is simple but well considered. Contained between two rows of shops and flats, it can only be approached from the front and the back. All technical and back-of-house access is at the rear, with the public foyer, including the box office and bar, entered from the new square and helping to animate it. The foyer is also a largely timber space, although in that case the timber used is Siberian larch, which is used not only to line the walls but for the glulam columns that support the roof.
Apex opened in October 2010, replacing as a venue the old corn exchange. Hopkins’ overall design for the Arc development placed an emphasis on connectivity to the existing town centre. It is intended to be an extension to the existing street life, not a replacement for it. Evidently people are finding their way to it – one of the few problems for the architect is gaining access to the venue, since it is almost fully booked for a wide range of activities. In the first autumn season, designated as ‘Sound Check Season’ to allow any fine tuning, more than 4,000 tickets were sold. Attendees at any of the performances and events are unlikely to appreciate the sophistication of the design. They will simply be aware that they are in a space that looks good and works well – and that is exactly how the architect and other members of the professional team would want it to be.