Property: Creating a space in the terrace

Not many people would be thrilled to find a period house with a plywood staircase, nasty cheap mouldings and plastic windows, but for Jill Brunstad it was perfect. She could sweep away the interior without a twinge of regret. As an American she favours an open plan lifestyle, as an architect she knew what was possible.

From the outside, the turn of the century terrace London house in Chelsea, bordering on Fulham, is like every other in the street. Three floors including a basement with a maximum of three bedrooms and a 17ft garden. They are smallish houses, not built for large families, and owners here, as in every city in the country, do what they can to fit contemporary lifestyles into narrow rooms that run front to back.

In gutting and redesigning the house, Brunstad did away with the constraints of the original structure and, without extending it, created a home that feels twice as large. A particular feature is a central atrium from the ground floor up to the roof. Galleried landings on the first and second floors look over the dining area.

"One of the foremost things was how to get natural light into floor plans. It was long, skinny and dark and we wanted to open up the centre," she says. "You can now see from the front to the back of the house and your eye only stops at the end of the garden. When you have a long view it makes everything feel that much larger."

This was not the kind of redesign that involves moving into the spare room and living off take-aways. It was a messy, hard-hat job that required precision and skill. Brunstad's two years working for Norman Foster's architectural practice enabled her to take the project in her stride. "We took out the load bearing wall and put in six steel beams to take the weight. All the calculations had to be exact. I am used to working with steel on the cutting edge of structural ideas and if your aim is to bring light into a space it makes no difference whether you are dealing with a skyscraper or your own house."

She also reversed the English principle of burying the kitchen away and moved it on to the ground floor in what would have been the front reception room with a bay window. "I regard the kitchen as the heart of the house, especially with children. I find it rather nice to watch people on the street while washing up and I don't mind if they look in, but I would resent it if I were relaxing with my feet up."

She says a lot of people's comment on the end result was "how interesting", but when the house was put on the market, opinions mattered more. The interest was enormous and it sold, through Sotheby's within days for 20 to 25 per cent more than is usual in these streets.

Perhaps not surprisingly, the buyer was an American as well as British citizen. Fraser Marcus and his wife had been looking for such a property for some time: "We wanted to stay in this part of London. We had been considering buying an old house and doing it ourselves, which is why as soon we saw this house we jumped at it."

Paul Tayler at Sotheby's is familiar with the wish lists of US and European buyers, and sees more than most agencies. Their research shows Americans buy mostly from other Americans or Europeans, particularly Germans or Scandinavians.

"They love the idea of London because of its history and architecture but the downside is that their living environment is determined by it. They would like to be able to float above historical London in a capsule. What they want is more open space, fewer floors and a high standard of fittings. This is not easy to find in areas such as Kensington and Chelsea and although a few buyers are prepared to consider Docklands, most want to stay in the places they are familiar with."

Jill Brunstad's radical changes would be beyond most people, he says. Staircases usually dominate Victorian and Edwardian houses and the decision to move it to the back of the building is not easy. "While the English mentality of being able to the close the door on a room is changing, by and large they do not want to live in a completely open plan home. But where the best of American and European practices can be adopted is in the plumbing and fittings. Even that might well involve putting in extra water tanks, strengthening floors and designing around things like shower cubicles which are often larger than we are used to."

While the vogue for fussy, poor and inappropriate imitations of period features may be past, Jill Brunstad is clear that had she inherited a lovely staircase and fireplaces she would not have removed them.

"All buyers like the original cornices, skirting boards and fireplaces and they can look wonderful in a modern setting," adds Tayler. There is a danger that unthinking modernisation could return us to the Sixties scenario where houses were stripped of anything that appeared "old", but it seems more likely that houses will continue to evolve from our lifestyles.

"Nobody wants lots of dark little rooms," says Brunstad, "but when I hear people talking about lofts in an old mansion I want to cry. They have completely missed the point."

Jill Brunstad will take on the design phase of a project from New York: 240 East 86th Street, New York 10028 (Tel: 001 646 414 8844) Sotheby's International Realty: 0171-598 1600.