as featured in self build & design magazine.

"One week after we had made the final mortgage payment for our bungalow we totally demolished the entire building," says Frank Peet. "It was a worrying gamble, but it has paid off and given us a far larger home and business premises."

Frank and his wife, Jane, purchased their three bedroom bungalow in Bexleyheath, Kent, in 1990, with the intention of renovating and extending the rundown property to create a six bedroom single storey dwelling. The couple run a small care home for three residents with physical and learning disabilities and, with one wheelchair user, needed easily accessible ground floor accommodation. They employed a local building company to construct the blockwork extension on their former driveway, and then moved in and live in the extended property for a number of years.

"The bungalow measured about 200sq.m, and as our daughter and son were then living at home it was always a bit of a squeeze", says Jane. "A major change to legislation regarding the building codes and Care Standards meant that, although our room sizes would have just been acceptable, we decided to buy a larger property in the area."

Frank and Jane had very specific requirements, and could not find a suitable house or a plot of land on which to build. Eventually, they decided to demolish their existing home and rebuild on an almost identical footprint, introducing rooms in the roof space to create additional accommodation.

They approached Southwark-based architectural practice Banfield Stevens Partnership, who had been recommended by a friend, and explained their needs for ground floor bedrooms and living rooms with separate accommodation for themselves on the first floor.

"It was only after our planning application had been accepted when we suddenly realised that, in our old property, the 60sq.m loft was where we had all our storage," says Frank. "There is no loft in the new design because the upper rooms are built into the roof space, so we decided to build a basement to accommodate storage and seperate laundry facilities. We re-submitted the entire application with the addition of a basement, which was initially refused, and it took nine months of negotioating before we got the go-ahead."

The planners preferred the new house to resemble the existing street scene and, from the road, the property has been designed to look like any other generously proportioned bungalow in the vicinity, with an integral garage and three dormer windows set into the roof to meet height restrictions.

The depth of the house ensures that visitors liken stepping inside to being in a Tardis - the interiors open out in all directions. The 12 by 4 metre partial basement level is completely submerged, and provides two additional rooms - one to either side of the central storage. On the ground floor a wide hallway leads to a living room and kitchen that run across the back of the house - a concept which mirrors the layout of the Peers' previous home. An office / visitors' room, four bedrooms and two bathrooms on this level lead off from the central hallway, where a cloakroom and the basement stairs are also located.

Upstairs, Jane and Frank's living quarters are composed of three bedrooms (one for each dormer window), two bathrooms and a large, contemporary open plan living room / kitchen / dining area, with soaring ceilings and huge sections of glazing over looking the garden. The full height windows and glazed pitched roof, set into the gable, resemble a raised conservatory and ensures that the south facing rear of the house is filled with natural light and in total visual contrast to the more traditional roadside approach.

Roof tiles salvaged from the old bungalow have been used for the rear pitched roof, while new concrete tiles have been used for the front and a central section of flat roof inset with rooflights above the stairs. "You can't see the front and back of the house together, and the contrast works quite well," says Frank.

The Peets searched for rental accommodation where they could stay during their build, and found a property with a ground floor bedroom and shower room suitable for a wheelchair user. It took them six weeks to clean and prepare this house prior to moving in, fitting a new kitchen, redecorating and laying carpets to ensure it would be comfortable during their stay.

Initially, they had hoped to incorporate the existing 1990 extension into their new house, but eventually decided to demolish the entire structure in order to save the VAT, which may be reclaimed for a new build - contacting Customs and Excise for an exemption certificate which they presented to suppliers.

Their lender would not allow them to proceed with demolishing the bungalow until they had cleared their final mortgage payment, and one week later the building was carted away in fifteen huge lorries - a process which the Peets found worrying but exciting.

Frank had seen a television programme about building with Beco, and realised that this would prove an ideal product with which to construct the basement and ground floor external walls. Beco Wallform is a permanent insulated formwork system, based on large hollow polystyrene blocks, which boasts superior energy efficiency and long durability.

The block components lock together without the need for intermediate bedding materials and provide a formwork into which concrete is poured. Once set, the concrete becomes a high strength structure and the formwork remains in place as thermal insulation. This may be clad internally and externally with a wide range of finishes, and is suitable for use both above and below the ground.

Building the Beco is a fast and tidy process as the lightweight blocks simply fit together in a modular grid, and Frank was keen to become involved. "As a first time selfbuilder it was a system I could understand, and something that I could physically do myself," he explains.

"Once the three metre hole for the basement had been dug we worked our way out of the hole with the Beco like giant Lego, with vertical steel reinforcement through the centre of each block tying the basement together. These basement walls were constructed in just three days, and the slab poured over the entire ground floor - leaving just a gap for the staircase. Suddenly this white box started to appear on the site, and was a major tourist attraction for a while!

"The only real mistake of the build occurred when concrete was pumped into the first lift of Beco walling - which just exploded. The hire company had sent the wrong type of pump, and the pressure was far too great and shattered the polystyrene.

"I don't think I stopped swearing for about two hours, and we had to do some fairly significant repairs, but it really wasn't too much of a hardship because the Beco is so quick to work with."

By using NHBC for both the insurance cover and Building Control inspections, the Peets only needed to work with one inspector, which reduced the risk of conflicting points of view and possible extra costs caused by delays. The National House Building Council's (NHBC) Solo for Self Build policy has been specially designed to protect selfbuilders during the building process and provide cover on the house for ten years after completion. It also offers the freedom to have the building work done by individual contractors, or to build some or all of the work yourself.

"Our main contractor was actually a master bricklayer - although there isn't a single brick in the house," says Jane. "He was recommended by our architect and undertook the majority of the structural work, with additional specialist subcontractors for the roofing, plumbing and some other trades. Frank was on site every day working alongside the builders, and we brought our residents along individually to explain all about their new home."