Contractor Kajima UK only began preparing a site in North Street, Leeds for a new-build scheme of apartments this month, but decorators have already started painting the walls of the kitchens, the bathrooms, the halls, and the dining rooms. The first and final tasks in housebuilding are being brought together by prefabricating half the apartments' rooms in the factory.

North Street is the location for the second of the Joseph Rowntree Foundation's CASPAR schemes dedicated to creating City-centre Apartments for Single People at Affordable Rents. With CASPAR the JRF has committed to testing both the burgeoning market for rental homes for single people, and innovative building techniques for housing them.

Architect Levitt Bernstein's design for the scheme is termed semi-volumetric, because the lounge and bedroom of each of the 51 m² one-bed apartments is built within the timber frame building. Kitchen, bathroom, the hall separating them, and the adjoining dining room are constructed in the factory of specialist timber pod maker Volumetric in a single module.

Kitchens and bathrooms are the obvious rooms to target for prefabrication because, from a construction point of view, they are the most labour-intensive, skills dependent and problematic elements. "Off-site prefabrication gives us the benefit of quality, rather than the hit and miss on site," says Mike Lewis, project architect with Levitt Bernstein. "Residents will get a better quality finish and a more predictable finish. There won't be the odd socket in the wrong place."

The entrance hall and dining room have been included in the 3.5 m wide by up to 8.4 m long module for simplicity, says Lewis. "It gave us the whole half of the flat. It was simpler to draw a line down the middle, otherwise it could have been tricky to join on site," he says.

Modules for the 45 apartments in the four to five-storey crescent building are standard, with only variation being for left and right handed units. "We put a lot of effort into working out the flat layout so that we were really happy with it," says Lewis. "Normally kitchen and bathroom finishes would be among the last things you would work on, but because they are volumetric units we have worked from the inside out. We developed the flat layouts, then the windows, the cladding, and the roof."

Lewis estimates the cost of the module will be comparable to conventional construction, within the scheme's designed £50 000 per unit build cost. "We were hoping it would be less, but this is a trial process," adds Lewis. "We will be learning from this and hopefully doing it again." Volumetric is already repeating the exercise, having just won a contract to manufacture combined kitchen/bathroom modules for a scheme by a Hampshire housing association.

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Building Homes