It made its name fitting out stylish loft apartments. Now, explains partner Duncan Chapman, nine-strong practice Circus Architects is changing its act to portable buildings.
If you have been to the New Geffrye Museum extension in east London, home to recreations of the nation's living rooms down the centuries, you may have been surprised by a painstakingly precise reconstructed loft apartment, circa 1998. The mini-loft is virtually fit to move into, complete with mezzanine bed platform, bare wooden Junkers and rubber Dalsouple flooring, and stainless steel kitchen units and ironmongery. Clerkenwell-based designer Circus Architects has managed to sum up not only the style of the decade, but eight years of work from its own portfolio.

Circus has epitomised the loft-living style, creating more than 50 projects in the capital for clients – the Manhattan Loft Corporation among them – and filling the pages of Sunday supplements and monthly glossies. But as urban style-setters move beyond lofts, and the epithet itself is applied to ever-smaller and more conventional apartments, the loft's main protagonists are themselves moving on. Literally.

In its next phase of development, the young practice will be concentrating its energies on mobile structures. Encouraged by the inclusion of its mobile cinema for the Scottish Highlands and Islands in the Design Council's November tranche of Millennium Products, it believes portable architecture has big potential.

"It's a very weak industry," says partner Duncan Chapman. "Most mobile buildings are essentially trailers, and the visual approach of a lot of the designers in this industry is extremely banal. It's not a new idea – Cedric Price and people have been designing pods that move around for years – but the only other architects that are really active in this field are Apicella Associates [now part of Pentagram]." Indeed, the lipstick red plywood "Bloid" that brightened up Trafalgar Square during Architecture Week last November was part of the practice's attempt to draw attention to portable architecture. As for new projects, Chapman will say only that he has "a number of ideas up his sleeve" and is "having a number of conversations" with potential clients.

"I want to try to get things built that haven't been conceived of in the marketplace before. We'll be suggesting new ideas to unsuspecting clients and trying to convince them that this is a good thing to do," he says.

The practice was set up amid the gloom of 1991 by Chapman, Nigel Reynolds and Andrew Hanson, fresh out of Edinburgh University. "We had no clients and no contacts," recalls Chapman. It has survived its adolescence on a healthy diet of lofts combined with a smattering of shop and office fit-outs, surgeries and mobile exhibitions, not to mention the occasional enquiry from confused clients trying to commission a big top. The Clerkenwell-based firm, now nine-strong, works on a consensus basis and always maintains a sense of fun in what it does.

This year will see the practice grow up. The office has reorganised itself since Hanson left in 1998 to help set up Harper Mackay spin-off HM2 (although he still plays in goal for the practice football team, Dynamo Circus). The plan is to become more business-minded, adopting a proactive marketing strategy and pushing its horizons beyond the nice little domestic projects that look good in the Sunday supplements. On the other hand, a healthy portfolio of reworkings of period properties for society clients will maintain the glamour quotient.

Primarily, Chapman would like to see the practice start making some money. Surprisingly, regular publicity in the lifestyle glossies, the completion of 50-plus yuppie pads and a handful of awards (including the £10 000 first prize in the 1994 Europan housing competition) have not brought the riches one might expect.

"I don't know what it's like when you're dealing with £100m schemes, but down below £250 000, it's difficult to make architecture pay if you want to maintain attention to detail. We've probably been overdrawn to the extent of our limit for 80% of the eight years we've been going," he declares with some degree of pride.

Although he is aware that repetition and linearity would be a more efficient way of working, as it would reduce the practice's workload, he fears this would destroy the very thing that drives him as an architect.

"We're about enjoying each project individually. We don't have such a thing as a house style – although if we see a brass finial, someone will find themselves out of a job." Although the practice would appear to be leaving the loft business at a rather opportune moment, Chapman refuses to subscribe to the theory, recently initiated by design magazine Blueprint and perpetuated by the Sunday papers, that the era of the loft is over, and refutes suggestions that the inclusion of the genre in a museum consigns it to history. "There will always be people who want the freedom that loft construction allows. I don't think that's going to change in a hurry."

Personal effects: Duncan Chapman

How did the practice get its name? That was Nigel’s idea. It was better than Sky Vaulter, which was my suggestion. Do you live in a loft apartment? No, I can’t afford to. I live in a two-up, two-down in Twickenham. What are your favourite Clerkenwell hangouts? The Coach and Horses, where all the Guardian hacks drink, The Eagle, and Al’s Cafe in Exmouth Market. What would be your ideal project be? A commission from the Tate to design a mobile gallery in translucent glass, steel and PVCu that could go round schools and hospitals showing all the work hidden in storage.