A DIY Self Build

Even if you should not happen to like the style of Roelof and Caroline van Silfhout’s contemporary self-built family home – which took more than a little inspiration from Roelof ’s native Holland – you could not deny that it is one of the warmest and most technically advanced houses in the quiet part of Cheshire in which it stands.

The van Silfhouts bought the 800m² plot, with splendid views to the Peak District, for £160,000 in 2001. It already housed a 1950s bungalow, but initial thoughts of adding a storey were quelled as the couple realised it could cost as much as £100,000 - making it far more economical to demolish and rebuild.

Roelof, a physicist at the University of Manchester, had previously built a stable block in Holland with his father and fancied the challenge of building a contemporary low-energy ‘continental-looking' house with a steeply pitched clay tile roof and white-rendered external walls.

Excitedly, Caroline bought Arcon's 3D Architect software and the couple set out to discover how difficult designing your own home really is. They knew the style of house they wanted: a free-flowing interior with spacious rooms and masses of light entering from all sides, with a full staircase up to the attic space and a small basement that would act as a plant room. To their surprise, with just one minor amendment, their own design for a three bedroom house was passed by Stockport District Council.

The couple never lived on site in the bungalow, but instead rented a flat 10 miles away in south Manchester for three years while Roelof spent virtually all his spare time building the new house almost entirely by himself, except for some help from his father when he was able to come over from Holland to assist. In the end there were only three things Roelof did not do - the groundwork and footings, rendering and plastering, and the floor screeds. "I used only three subcontractors, and even built and clad all the roof myself," says Roelof. "I didn't originally plan it that way, but that's how it worked out. My father, Arend, helped with dry-lining and formwork, which was really useful. It would have taken so much longer without his help."

The first major task was to demolish the existing bungalow and dig the hole for the basement, which acts as a plant room and store. The footings and basement construction were built in a fairly conventional fashion, but almost everything else in the 187m² ecologically orientated house was not.

For several years Roelof had been impressed with the idea of insulated concrete formwork. The house is built using two of these systems - Beco and Styro Stone. Roelof says: "I had been familiar with a similar German system and I always thought it ideally suited to self-build because it is so easy to work with.

"However, to a physicist like me, the problem with systems of this sort is that they do not make enough use of the sun. I am very keen on what I call ‘thermal flywheels' that store and release heat energy from the sun inside the house. One way of achieving this is to have solid concrete internal walls, so I used the concrete pump, while it was on site filling up the insulated formwork, to create solid concrete internal walls, which I then dry-lined with Fermacell.

"In addition to this I designed highly insulated floor screeds, in which a thin (25-40mm) self-levelling screed was poured over a thick layer of polyurethane board." The design of the first floor is very experimental. The building inspector stood agog - both amazed and fascinated - as he watched 30 tonnes of concrete being poured onto 175mm-deep Styro Stone blocks.

"I wanted the greater insulation that the Styro Stone system affords and with conventional beam and block you can't insulate the ceiling very well," Roelof explains. "So I used steel I-beams with Styro Stone blocks between and calculated that with a steel mesh above they would hold the concrete. We held our breath as the concrete was poured. But it worked!"

To construct the roof Roelof adapted a car engine crane by extending the hydraulic arm to lift the three huge steel beams that form the ridge and the purlins. It saved on hire charges, but caused endless worry to the neighbours, because he did it all off a ladder using no scaffold. "I heard from our very tolerant neighbours how scary it was watching this crazy scientist erecting a complete roof on his own!" laughs Caroline.

Because of its complex shape, Roelof found the roof carpentry very difficult. "I used a computer program to calculate the angles," he says. "It was still quite difficult because I wanted most of the roof timbers to be exposed in the vaulted ceiling in the master bedroom, so it had to look really good."

Not content with all this, Roelof has created an attic that is reached by a fixed staircase - an extension to the entire staircase in American oak which he designed and built himself. There is also a 76m² double garage with a large workshop attached to the rear of the house. An internal staircase leads from the workshop to what will eventually be Roelof 's study.

Roelof says: "In addition to this we have the potential for two more bedrooms in the attic space with its fixed stair, plus the room over the garage, so I feel that, with the basement, we have developed the site to its best capabilities.

"I still plan to install a solar array on the south side and also a small wood-pellet boiler. That way we hope to eliminate gas heating altogether. We already have a grey-water system that stores rainwater in a large tank beneath the front garden and reuses it in the WCs, the washing machine and for garden watering. Inside we have central ventilation and a heat recovery system which both conserves energy and keeps the atmosphere constantly fresh.

"Although some parts of the build were definitely very hairy, especially building the roof and laying the floor screeds, I enjoyed almost all of it - despite the fact that it took four-and-a-half years, which was about two years longer than I anticipated. I guess I am the sort of guy who just loves to have a project on the go - even if it turns out to be a real challenge!"

Building with Insulated Concrete Formwork (ICF)

Building with insulated concrete formwork is a fantastically quick way to build a house’s superstructure, and can even be done by the DIYer, as Roelof proves. Polystyrene moulds are erected on site, joined with steel ties, and then filled with pumped concrete before being reinforced. Not only is it quick, but it also provides an impressively efficient wall structure, with most systems providing a Uvalue of around 0.2. In addition, an ICF house contains far fewer elements than in a regular masonry house — no lintels, less wall ties, etc. The lead-in times are not significantly long as the polystyrene moulds are easily available. However, it is essential to ensure that you get the ready-mix concrete right, and also guarantee that there is significant support and bracing to the walls as the pour occurs. As long as these essentials are carried out with care, ICF remains a highly attractive alternative to standard brick and block, and offers first-rate results.

Further reading:

• A Hillside Home Built for £140,000
• A Scandinavian Home in Scotland
• The Secrets of Building to a Budget