The prefabs are sprouting

16 Nov 2005

A marriage between architects Shed KM and Yorkon, the modular buildings manufacturer, might seem like an unlikely match.

Yorkon produces a range of prefabricated units, including MacDonald’s drive-ins and Shed KM designs highly controlled and elegantly simple housing in which every detail counts. However, the award-winning Moho (short for ‘modular housing’) project at Timber Wharf in Manchester combines the skills of both parties to maximum effect.

Describing his first meeting with Yorkon, James Weston, project director at Shed KM, recalls: “I walked into a giant hangar and there are five McDonalds in various stages of assembly, complete with chairs and tables. At the end of the manufacturing process, you are given one last choice – is it buff brick or brown brick. That is how choice has been exercised in the past.” Shed KM has taken the best from the manufacturing process and extended the range of choices to create homes that are relevant for the highly-discerning housing market serviced by Urban Splash.

Moho is the first private sector multi-storey development incorporating prefabricated modular units in the UK. The design process was more demanding and time consuming than designing traditional house-types but, once the design was fixed, Yorkon produced six modules a day and it took just 18 days to completely fit out each unit. It’s not the first scheme of its kind, but previous schemes have been produced by social landlords such as the Peabody Trust and have been seen as experiments in new procurement methods rather than commercial propositions. Urban Splash has already sold 60 per cent of the Moho units in a rather sluggish market, so the project is likely to be a commercial success.

The building was the product of a competition organised to meet the demand for affordable housing that could be brought to site quickly. Shed KM made one very simple but important design move; to abandon the convention of stacking units together like fish fingers in a pack and to put them end to end, creating a long external wall that could be glazed and allow light into every room in the module.

“Our contribution was turning the unit by 90 degrees. I think this is now an accepted principle. Splash like to do units short side on, but they can see the benefits of placing units longways – as long as you can get the density you are looking for on the site,” says Weston.
The flats are small, a one-bedroom flat is just 38 square metres with a long balcony clipped on, which adds an extra ten square metres – the larger two bedroom units are about 54 square metres. Each flat is contained within a single module, but there are optional clip-on dining pods that sit besides the balcony.

A wet core in the centre contains a gallery kitchen overlooking the balcony and a bathroom with a bath accessed from one end. The approach has allowed the architects to create an airy, open-plan feel in a very tight space. The design team produced a full-scale model to study the location of all fittings and, as a result, the units are unbelievably clean-cut and seamless. Each module is made up of a highly insulated lightweight steel frame, which is shipped to site and then slotted into a steel frame structure that supports the deck access and provides rigidity to an independent frame that supports the balconies. The fit-out design is more akin to boat building or product design than architecture; most things are built in. The units, which went on the market at £131,000, are furnished with fitted cupboards and furniture supplied by Mooch.

The organisation of 102 units on the site follows the EDAW master plan for the area. The £9 million U-shaped building with a central court is accessed through the middle of the main elevation. A lobby at ground level opens into a courtyard that slopes up to the first floor. A circular concrete drum contains a lift and stairs that provide access to the deck access walkway on every floor. From the court the building feels like a liner. Exquisitely detailed handrails and uninterrupted glass balustrades banish any association with the recently demolished deck access concrete blocks of nearby Hulme. On the two wings of the U-shape the units are double banked, but again the corridor between units is open with some light borrowed from above, an approach that avoids the misery of the sterile dark residential corridor. The client has even been bold enough to install a rubbish shoot, one of the old emblems of the failures of post-war social housing and collective living.

The prefabricated approach may save time on site, but is not a way to save money; as a rule prefabricated units come in up to 10 per cent above the cost of traditionally constructed units. The benefits of the system could only really be gained in the quality of finish provided to the end user, time saved on site to the designers and clients, time saved over snagging for clients and contractors and in the long run through economies of scale.

Chris Stalker, the project director for Urban Splash, estimates the construction cost of the modular building is estimated at about 5 per cent more than traditional construction. Urban Splash is still evaluating the benefits of this approach and may engage in a more in-depth study of the merits of this approach. They are in a particularly good position to do this, as they have built a scheme with a very similar brief, designed by Glen Howells and built using traditional construction methods, on the site next to Moho. Moho probably cost about £1 per square metre more than Glen Howells’ building, “but pounds per square metre is quite an unscientific way of thinking about buildings“, says Weston. “We would hope to use the idea again hopefully with Splash. There was a learning curve with this project. Our understanding is that the design rests with us,” he adds.

To date, most prefabricated housing has been dubbed ‘McHomes’ and been understood as a compromise. The prejudice that you can’t make gains at the level of build quality and programme without having to make sacrifices in terms of design quality, external appearance and relationship to context is strong. One of the cultural barriers to prefabrication, apart from the association with the failures of Sixties and Seventies social housing, is that the systems tend to be hard to adapt and therefore rarely capable of providing a contextual response and the absence of separate cladding systems tend to create buildings that look dull and lightweight.

At Moho there was an unusual amount of finishing on site to tie the projects together. “Moho sits strongly in the place. It’s a very urban building; it looks robust and appropriate, the reddish timber cladding which reflects the surrounding industrial mills buildings,” says Weston. “The thing with these types of offsite schemes is that very little is done on the outside and as a result they tend to look thinner, but Moho is very robust; there are layers and depth to the elevations. The work and time spent on site is valuable. I personally think that prefabricated should be understood as one component in the process. I prefer that approach to the idea of that rather utopian vision that everything has to be finished in the factory.”

Weston admits that it took a while for his practice to get to grips with the parameters of designing for prefabrication and for the manufacturers to appreciate the level of design detail that he was looking for. However, he thinks one of the biggest culture shocks was for Urban Splash. “The client had to freeze the internal unit design very early on in the process, which they would not normally do. They had to say, ‘yes, this is the specification’ and then they couldn’t change their mind. I thought that was really good,” says Weston.

There is also a question as to whether the industry as a whole is able to adapt to this kind of working. “This kind of system is only as good as its weakest point in the process,” says Weston. “If you want to build a scheme like this to shorten the construction period then you have to be prepared. If all the units arrive on site at once then the enveloping process needs to be manned up accordingly, to maintain the benefits. If you have a meeting with the sub-contractors on site a month before the units arrive and say, it will all be ready in a month, they find it hard to believe.”