Deeper and deeper

When the going gets tough, the homeowner gets digging. Graham Norwood explains why basement extensions are a smart investment

You need another room but already have a loft. You want more space but dare not move house while the market is falling. There is only one solution - go underground.

You need another room but already have a loft. You want more space but dare not move house while the market is falling. There is only one solution - go underground.

Basements can be as cheap or expensive as you wish, depending on what you use them for and whether your home already has a cellar. "Why risk losing out through falling prices, then lose out again by paying stamp duty?" asks Home Search Bureau's director Jerome Kitson, a buying agent who expects a sharp fall in house sales this year as people choose to extend instead of move.

Almost any property built before 1960 can have a new basement. "Victorian houses are well suited if they have small cellars with old coal chutes beneath suspended timber floors," says Maggie Smith of The London Basement Company, which specialises in converting large homes in the south-west of the capital. "From the 1960s many houses were built with solid floors and stronger foundations, so it's more difficult - although not impossible," she insists.

The Basement Information Group (BIC), a body of conversion firms and enthusiasts who promote cellars as living spaces, says they are better than any other extension for the following reasons:

* They can extend the full width and depth of a property - even run beneath a garden - to provide more space than lofts conforming to the shape of a roof.

* They can be full height rooms because most drains are built to the sides of older houses, making it feasible to dig to a depth of three metres.

* Many basements do not require planning permission unless they are used to provide separate, self-contained accommodation.

* A basement can make a home 10% more energy efficient by releasing underground heat which rises through the rest of the home.

* Tanking a basement - lining it with a metal skin to deter damp - allows it to be used for any conventional purpose.

The BIC, with the government think-tank the Building Research Establishment, is holding a conference this month to raise awareness of basement living. But some people have already beaten them to it.

Jennifer Brawdley, a lifestyle and business coach, decided that the only way was down when she became pregnant in 2002. She converted two adjoining coal chutes, each 12 feet by four feet, beneath her two-bedroom flat in Streatham, south London. "It was an excellent but entirely useless space, because the floor was just soil, the air was damp and the brick walls had mould. You couldn't store bikes or paint cans down there because they would rust."

So she hired builders to tank the chutes, move a boiler from the kitchen, install lighting, running water and central heating, and decorate the finished space. Now she uses the area as a laundry, a home office, clothes store and occasional bedroom. Brawdley moved out for 10 weeks when the work was done but says the inconvenience and the £20,000 cost were worthwhile. "It's transformed my life. My kitchen is more spacious because the boiler has gone, I can work from home and there's plenty of space for my daughter Lydia" she says. She is now moving across London so is selling up for £229,950 (through Kinleigh Folkard & Hayward, 020 8769 8744) but reckons the basement has added much more than it cost.

Some estate agents believe, however, that larger and more sophisticated conversions are only cost effective on properties worth at least £500,000. Most urban basement specialists charge £90,000 to £150,000 plus VAT, depending on size. The London Basement Company says an existing cellar can be turned into a full-size basement in 16 weeks but it will take 24 weeks starting from scratch.

In some cases a mini-JCB does the initial excavating from outside the property and then workmen use props to support the house; but often owners must move out while the ground floor is taken over by men with pick axes and diggers. The potential for mess is obvious: "I've seen men in waders pumping out water while they've been digging," cautions Maggie Smith.

If you do spend a six figure sum do not expect an overnight profit. "Anyone considering converting a basement needs to look at their reasons. If the extra space means they don't have to move for three years, it will be worthwhile. But anyone thinking about converting it to add short term value will probably be disappointed," suggests George Franks of estate agency Douglas & Gordon.

According to Douglas & Gordon, many of the houses on the Peterborough Estate, in Parsons Green and on the roads between Munster Road and Parsons Green Lane have already had their basements converted. A good example of a house with a very smart conversion currently on the market is in Bradbourne Street, SW6. This is a five-bed house extending to 2,759 sq ft, which has had the basement converted into a kitchen/dining room, and is for sale through Douglas & Gordon (020-7731 4391) at £1.5m.

Providing you keep costs to a minimum, there has never been a better time to dig down. With the high cost of moving and house prices dipping across the country, we are definitely in a cellars' market.

www.basements.org.uk

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