Two young architects discovered that prefab is being taken over by developers who think it means putting toilet pods everywhere – and vowed to fight back … Martin Spring found out how they're doing
Like so many building professionals in the Egan era, Martin Wood and Mark Bryden are evangelists. The good news that the two young partners of Bryden Wood Associates are spreading is that industrialised construction offers high build quality, rapid build time and low build costs. So far, so familiar.

The difference between Bryden Wood and other architects that have embraced modular design, however, is that the practice has submerged itself so deeply in the practical details and industrial processes of prefabrication that it acts as an industrial designer, or even a production engineer.

This ability has driven the partners into becoming prefab entrepreneurs: they have set up their own assembly plant in Hull in a joint venture with Commercial Systems International, a local curtain wall manufacturer. Trade contractors such as NG Bailey are brought into the manufacturing process by supplying pre-tested components to order.

Engineering consultants, or more precisely individuals within practices, contribute to the design process, although Bryden Wood, as lead consultant, insists on carrying out all design drawings itself. These individuals are structural engineer Jim Gardner of Alan Baxter Associates, services engineer Richard Simpson of Oscar Faber and public health engineer David George of Arup. Simpson gives an idea of the level of design detail involved. "We spent several days around a table discussing a pipe bracket. In system building, a pipe bracket is such a fundamental part of the whole design concept and installation process."

And unlike other architects, Bryden Wood resists the seductiveness of large volumetric pods or boxes, which are effectively miniature buildings in their own right. "Everyone wants iconic images of large modules or pods to hang their hat on," says Martin Wood (left in the photograph, opposite). "But the iconic box is a stumbling block, because it doesn't have flexibility."

In the seven years of Bryden Wood's existence, the London-based practice has designed prefabricated modules for toilets, hotel bedrooms, service spines, a cyber cafe and street market stalls.

"The products we design are incredibly eclectic and range from the biggest thing you can put on the back of a lorry, like the services spine for a server farm in Madrid, down to something so small you can hold it in your hand. We have lots of subsets of techniques that we can combine in different ways to achieve flexibility."

Although revolutionary for an architect, the assembly plant set up by Bryden Wood is a basic affair in an industrial shed. "The key is not to rely on large production lines," says Wood. "All you need is an assembly point for a lot of components. You don't need sophistication, because this is taken care of by the component manufacturers who use computer-controlled techniques."

And Hull has several big advantages. "It's is a cheap place to build – industrial labour costs there are just a third of site labour costs," says Wood. "It has a skilled workforce, good links to the Continent and various useful light engineering companies scattered around."

Before setting up on their own, Mark Bryden and Martin Wood worked at high-tech architect Nicholas Grimshaw & Partners, and still work for the practice as subconsultants, designing phases of the Igus factory in Germany. The partners still believe in employing architects rather than industrial designers. "Architects get the wider picture, and it's better getting them to look at the detail than trying to get an industrial designer with a narrow perspective to think wider. They are able to apply lateral thinking to services and production design."

Despite its immersion in industrial processes, Bryden Wood has not abandoned its architectural roots. This is obvious in the high-tech visual elegance of its designs, as in the Zeds modular hotel system. It is also evident on a more practical level in its ability to make the most efficient use of space within its buildings.

Bryden Wood is not on course to become a great signature architect like Grimshaw, but it could still have a profound if inconspicuous impact on efficient building design and production.

Bryden's bijou berths
Bryden Wood has designed a modular hotel called Zeds, in which bedrooms, complete with showers, can be simply stacked on top of each other. An eight-room prototype was built two years ago at the works in Hull, and planning applications have been submitted for three sites in London and Manchester.

Zeds is the concept of an ad-hoc innovations company, Hamstead Securities, rather than an established module manufacturer such as Yorkon, which perhaps explains why it has taken 10 years to reach planning application stage. Undeterred, the company claims that where Zeds scores over existing volumetric budget hotel systems is that it is considerably more compact, which means – Bryden Wood says – that it is about one-third faster and cheaper to build, and that more revenue-producing bedrooms can be fitted in the same building envelope. This, in turn, allows the system to better exploit expensive city-centre sites where tourists want to stay.

A Zeds bedroom measures 2.4 × 4 m internally, or 9 m2, whereas a conventional volumetric bedroom measures at least 15 m2. This compact form enables two hotel bedrooms with an intermediate stretch of corridor to be prefabricated as a single module measuring 10.35 × 2.6 m, which is small enough to fit on the back of a lorry.

"As architects, we have brought a greater interest in the compact design of space," says Martin Wood. "We have tried to bring a sense of design and quality to a smaller footprint. It's like the difference between a caravan and a luxury yacht: The yacht is smaller inside but it is more attractive to live in."

Bryden Wood's design includes sophisticated space-saving features. Two fitted bunk beds at right angles to each other and a triangular shower allow space to expand from the doorway to the main living area of the room. Other features are psychological: the shower room is encased in translucent panels so that that it appears as part of the main volume of the room, and high-quality materials, including polished hardwood, give a sense of luxury.

Zeds has one final competitive trick up its sleeve. The modules are made as rigid steel stressed-skin boxes, which means they can be dismantled and relocated on short-term sites.

Bog standards: rethinking the toilet pod

Bathroom and toilet prefabrication is invariably taken to mean volumetric toilet pods. But Bryden Wood questions this orthodoxy, arguing that the floor, ceiling and at least one wall of a bulky volumetric pod are all redundant, since they are all provided by the building shell. So, for Bryden Wood’s Rapid Assembly Toilet System, the practice went for an Ikea-style flat-pack approach. Instead of a bulky pod, each element of the system – WC, urinal, washbasin, hand dryer or shower – can be purchased as a separate standard prefabricated module, each of which is fitted to an elegant cassette. This is made of stainless steel and toughened white glass and comes with overhead light fitting and ventilation grille, and with all the supply, waste and soil pipes and electric cabling prefitted at the back. The beauty of the system is that toilets or shower rooms can be made up of any permutation of modules, all of which come with the same overall dimensions. The kit-of-parts can be rapidly installed in either new-build or refurbishment projects, as they are small enough to be carried, bolted together and plumbed by two operatives. Prefabrication also offers the dimensional accuracy and quality assurance of computer-controlled components that have been pre-tested in factory conditions. The toilet modules are economically manufactured in the Hull workshop that Bryden Wood set up with local curtain wall maker Commercial Systems International. To date, they have been used at Art Space art studios in Birmingham and office buildings in Amsterdam and Paris.

The supercharged switch test

For its Optimum Switch project, Bryden Wood focused its prefabrication expertise purely on services fit-outs. But these services are not just on any old buildings – they are in multistorey internet server farms, which demand a more supercharged concentration of cabling, power and cooling than any other building type. Last August, the practice completed the installation of prefabricated services modules on the ground floor of a server farm in Madrid for British developer Global Switch. The modules were prefabricated in an industrial shed in Hull leased for the purpose by Optimum Switch, a company set up jointly by Global Switch and Bryden Wood. “Services are usually spread around all the internal surfaces of an office building, because that is convenient for conventional on-site building techniques,” says Martin Wood. “What we have done is to condense or distil the services into the smallest space, and this reduces unproductive floor space occupied by services and the pipework and power distribution, which are all very expensive. This concentration is only sensible if you prefabricate the components in factory conditions. We reckon we have achieved an all-round cost reduction of 25-30%.” The conventional server farm arrangement is to run a ring of corridors and primary services around the perimeter and along the centreline of each floor. In Optimum Switch’s condensed model, one single corridor spine entirely wrapped in services plant is run along the centreline. This central spine delivers power, cabling, cooling and security infrastructure, and is flanked by air-recycling units. Secondary power distribution booms run off at right angles from the spine over the IT switch racks. Chilled air is supplied from beneath a raised access floor and returned at high level. A total of six-and-a-half service modules, each 15 m long, were fully prefabricated on jigs in the Hull workshop, which came with a 20-tonne overhead crane. Components such as pipes, ducts and cables were precision-engineered to size and pressure-tested by subcontractors, including services contractor NG Bailey. After delivery to the workshop, they were then assembled within rigid steel cages using self-welding techniques. The prefabricated modules were then trucked to Madrid for final installation. The entire prefabrication process took only 10 weeks. “Speed was of the essence in this project and cost secondary,” comments Wood.