A Three Storey Self-build with a Basement

"Most people would have dismissed our site as too small and awkward," says Robin Towers. "It is triangular in shape with a road on one side and a footpath to the other. One of the planning officers even said to me, 'But you don't have a proper front and back garden,' whilst another wanted us to build one metre from the footpath which would have given us views directly onto a high fence!"

When Robin, a designer, heard about a house for sale in Kew that had a large garden, he persuaded his wife Gillie that they should try to buy it. "Infill sites in this area are pretty hard to find," Robin explains. "Although we lost out on the house, I asked the new owners if I could help them to apply for planning permission. After two years of deliberating, they agreed to go ahead, and I secured consent for a new house."

The application caused a flurry of curiosity from interested builders, and Robin and Gillie were asked to match the highest offer if they wanted to buy the plot. They paid £225,000 for the triangular piece of land, sold their previous house and moved into rented accommodation directly opposite the site.

The position of an existing garage ensured that access onto the site was relatively straightforward, although the planners insisted on two car parking spaces which further reduced the size of the plot. Designing a suitably large family house on such an awkward piece of land was a real challenge, and most people would have resigned themselves to building a modest two storey dwelling of traditional design. Robin's innovative solution overcame the planners' objections by burying the lower level below ground, using this basement as habitable space with natural illumination from a large lightwell/lower basement level courtyard. He researched the topic by attending exhibitions and reading books and articles about basement construction prior to employing a structural engineer to calculate the technical specifications for the build.

"The planners' insistence on a maximum eaves height of 3.5 metres meant we had to have dormer style windows, which I felt sat best in traditional materials," says Robin. "Building a basement required specialist contractors, and it therefore made sense to manage the project myself and employ individual trades rather than one main contractor. I would guess that I also saved money this way, although I think I would use a quantity surveyor in future in order to budget more accurately."

Robin admits that building a watertight basement can be difficult in this country, and took a calculated risk with his own design which is located quite close to the river. Kew once flooded on a regular basis and he was aware that, by digging down three metres, there was a chance of hitting water or even an old air raid shelter.

"Although I dug a couple of trial holes I didn't know if we would end up having to drain the site using a pump and a series of suction points to keep the water level down," he says. "That would have proved expensive and complicated particularly as we were building right up to the boundary." Fortunately, the ground proved dry and sandy. The weather was appalling but rainwater quickly drained away - much to the Towers relief.

One contractor was employed to construct the concrete box basement, using a JCB to excavate the hole, which filled several lorries with spoil to be removed from the site each day. Six metre deep sheet piling was specified to retain the pavement and road which bound the site.

"If we had not been building so close to the boundary then it would have been easier to excavate the hole with sloping sides, build the basement and then backfill," says Robin. "The reinforced concrete slab has a membrane beneath it with a small kicker around the edge and an expanding water bar, which takes several days to activate - allowing for rain. Waterproof concrete was poured using large metal panels as shuttering, with a Sika waterproof render to make absolutely sure. It was all a bit belt and braces."

Robin tackled some of the physical work himself, including the setting out, labouring and keeping the site clean. He also undertook some joinery and decorating as well as purchasing materials. Gilly had been sceptical about building - following many years spent renovating the family's previous home - but she loves the use of different levels in the new house.

"People are always surprised when they visit and first see the basement," she explains. "They expect it to be dark and dreary, but our living room is flooded with light and overlooks the courtyard - which is a real sun-trap. The kitchen is the heart of the house, where we spend most of our time, and visitors tend to gravitate towards the bay window seat to look out."

"Initially, our neighbours objected to the idea of a new house being built on the garden site, but they have been very complimentary now that it is finished. We have managed to build a spacious family home without detracting from the surrounding area simply by sinking it into the ground."

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Further reading

• Basements - The Pros and Cons
• An Eco Home with a Basement Swimming Pool
• Site Specific Solutions for Problem Plots

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