Having only 16 weeks to construct a house from scratch is a tall order by any standards. If it is also a self-build project on a tight budget, then the stakes are raised even higher, with no room for mistakes or even second thoughts. When Philippa and Stephen Evans found a Fifties bungalow in rural east Sussex with magnificent views and 1.9 acres of land, it seemed the ideal spot for the family house they had in mind. Stephen, a civil engineer, drew up basic plans, submitted these to the local planning authorities and sat back to wait. To their surprise the plans were approved quickly, but not before the vendor wanted an extra £50,000 for the bungalow and land.
Their goal seemed tantalisingly close and after negotation they settled on a figure just short of the £300,000 being asked. However, they were about to be pushed for time as well as money. "We got an offer on our house in a nearby village almost immediately and the purchasers agreed they would wait four and half months, but no longer," says Philippa.
With such a tight deadline looming, Stephen needed to find a fast method of building that would not compromise quality. Since he wanted to design the house himself, he ruled out a timber-frame package and went for an off-site construction company that would follow his own plans. He settled on a system known as Sips (structural insulated panels), manufactured by BPAC, a company based in Scotland. Stephen explained that the panels, pioneered in the States and relatively new to the UK, are notably strong and quick to construct: "They arrived on a low loader with four men from the company, who took only one week to build the frame," he says. "After that we used local builders and specialists, in the same way as you would with any house. This was all taking place over the summer and so once we had a dry shell, we really didn't worry about finishing it in time. At the very worst we could have lived in it - it would have been a great deal better than camping."
Far from coming to that, the project finished well within the deadline and for a build cost of £244,000. And because they were managing it themselves, they had the fun every evening of poring over plans pinned to their kitchen noticeboard. "We changed very little as we went along, although we could have done because it was not difficult," says Philippa. "When we came to fitting an old French cupboard into the kitchen and found the doorway was too far to one side we just cut a bit out of the panels and moved it over."
At the heart of how the Evanses envisaged their home was space in their main living area. To this end, Stephen included a basement (a solid concrete structure) for their daughters' bedrooms, playroom and bathroom, plus a guestroom. Light-wells and access to the garden from these rooms have removed that below-ground feeling. "This meant we could use the space in the rest of the house creatively with high, vaulted ceilings, some to a height of five and half metres. And the real advantage of this panel system is in the roof. Unlike traditional methods, it went on in two days and can span in any direction."
The kind of flexibility and speed of construction that impressed them are factors that suggest systems-built homes could be one answer to the housing shortage. The Government has said it would like to see 25 per cent of new homes built using off-site manufacture systems. Certainly, old prejudices against prefabs - which for so long were seen as cheap post-war emergency measures - are disappearing, as Scandinavian, German and American expertise finds its way into the British market.
Of the 50,000 or more people who visited the recent Homebuilding and Renovating Show in Birmingham, many were attracted by new construction techniques that appear to offer speed with quality. From the extreme of small pods that can be craned on to a roof top, to a fully fitted house with a plumbed-in bathroom, they have the advantage of being made under factory conditions. Corners are precision-engineered to minute tolerances and walls that are true should mean perfect tiling in kitchens and bathrooms. And because the shell is watertight within days, bad weather doesn't disrupt progress - work can be done on the inside and outside at the same time.
Although many off-the-shelf designs have only limited flexibility, the range of house types is far wider than perhaps many people realise. While some might recognise the distinctive glass and post-and-beam Huf Haus from Germany as contemporary pre-fabrication par excellence, a lookalike Tudor manor house is more surprising.
Border Oak, a small Herefordshire company, manufactures and constructs oak-framed houses; from thatched cottages, to farmhouses with a medieval-style open hall. The total cost of the firm's Meadowsweet Farmhouse shell, for instance, is £167,403 including doors, windows and staircase. It also offers a bespoke design service or will work from an architect's drawings.
At the other end of the scale is Potton, which has been producing timber-frame systems for 40 years, and supplies developers as well as the self-build market. It has 61 house designs on its books. Once the foundations are dug, Potton's "total house" packages, including details such as architraves and iron-mongery, can be erected in no more than two weeks.
Westbury, a developer at the forefront of research and development of new types of construction, has built 1,500 homes with its own system of prefabrication since 2001 and hopes to increase the percentage of houses it builds in this way to 40 per cent of its annual total, which last year was 4,500.
The bulk of the new-homes market is not innovative and for many purchasers the old notions of prefabrication still hold sway. Some people wanting this type of new home may even have been turned down by mortgage lenders. Sue Anderson for the Council of Mortgage Lenders says that although there is no problem industry-wise, individual lenders may take a different view. "The matter is on our radar because there is an issue of longevity with any non-traditional type of construction," she says.
But for those like Philippa and Stephen Evans, the advantages are clear. They have a four-bedroom, weatherboard house with an American appearance and feel, built to their own design. For a total cost of £527,719 they own a home valued at more than £750,000.
Stephen Evans, Building By Design: 01435 884800
BPAC: 01592 882202
Border Oak: 01568 708752; www.borderoak.com
Potton: 01480 401401; www.potton.co.uk
Westbury: 01242 236191