Best laid plans

Most of the Housing Forum's demonstration projects find that their innovative build methods are only really put to the test when they arrive on site. But Wimpey Homes, housing association The Guinness Trust and modular building maker Britspace are having to square up to challenges much earlier.

The team are set to develop around 50 homes across two Essex sites for the housing association. But before development of the country's first schemes of two-storey modular houses can begin in Romford and Chelmsford, there have been lengthy negotiations with local authority planners.

Planners can see exactly what modular houses look like, as almost a year ago Britspace manufactured and assembled a pair of semi-detached homes at its factory in Gilberdyke, east Yorkshire.

Although the houses were actually made from eight cold rolled galvanised steel frame modules with steel stud wall panels, from the outside they looked ultra-conventional with their brick slip cladding and Decra Roof Systems' granite-faced steel roof tiles.

Conventional looks, however, have not been sufficient to persuade the planners of the homes' abilities to fit into the streetscape; unfamiliar materials and build methods have given rise to some concerns.

"The roof tiles were not liked by the planners on the first two sites," says Jeff Baker, director of The Guinness Trust. "We also have a difficulty with the window details, as we have much less wall depth than traditional construction so we can't get the traditional depth of reveals. Some planners have also raised concern at the brick slips." Negotiations over these issues are continuing for the Romford site, but the Chelmsford site has been given the green light - albeit with Eternit roof tiles instead of the Decra product - and work is scheduled to begin on site next month.

In the trial conditions of Britspace's factory yard, assembly of the prototype three-bed semi and its two-bed neighbour went like clockwork. It took just three weeks to manufacture the eight modules, complete with their fully-fitted kitchens and bathrooms, and five days to assemble them on site.

Homes arrived on site 80% complete and site labour carried out minor tasks such as adding strips of brick and tile at the interface of modules. The Guinness Trust and Wimpey Homes were impressed by the quality of the Britspace product.

The team commissioned the Building Research Establishment to evaluate the build method, which although new to homebuilding is widely used for other building types, most notably McDonalds restaurants.

BRE's study has found that the manufacturing process reduces potential for problems in the modules to a minimal level, but that there is still a need for close supervision on site.

When the schemes get on site, the assembly process and the homes themselves will be measured against more conventional construction with a series of benchmarks, ranging from defects in the finished product to the amount of disruption and inconvenience that the build process causes to neighbours.

Both projects will be carried out under partnering arrangements, although Wimpey, The Guinness Trust and Britspace have effectively been partnering for two years to bring the modular homes concept through to site.

Cost is not included in the benchmarks for the first two schemes. Baker is nonetheless optimistic that the relatively small quantities of modules being manufactured for the initial sites should not result in hefty cost penalties for the housing association. "It should cost no more than conventional construction," he says.

As the first site gets ready to receive its convoy of low-loaders packed with home modules, the housing association is also having to consider the management issues arising from modular build. "The speed of assembly means that nominations will have to be rethought," says Baker.