A basement as an investment in West London

For a homeowner in West London, adding space is rarely a matter of choice. The choice would be between up, out and down. The plot is fixed. The roof is often already converted. The garden is usually protected or too small to give away. So people go down.

What a basement gives you

A basement takes the rooms that do not need daylight and puts them underground. These include a cinema, a gym, a wine cellar, plant, utility and storage. That frees the floors above for bedrooms and living space. That is the part that actually changes how the house works.

It also adds floor area without changing the elevations. That is why it survives planning in a conservation area. A rear extension would not.

Does it pay?

That depends on three things. One is what the finished space is worth per square foot in your postcode. Another is what the build actually costs on your ground conditions and access. The last is how much value you recover when you come to sell.

Nobody can promise a return on it. Anybody who quotes you a fixed percentage has not seen your house. What we can do is give you an accurate construction figure early. Then the arithmetic is yours to do. Our own basement rates by specification are published in the NU Build Cost Calculator.

Modern basements are not cellars

A well-designed basement is bright and dry. Lightwells front and back all bring daylight down. So does a subterranean courtyard, or a generous stair opening. Finished ceiling height of 2.8 to 3 metres is what stops it feeling underground.

All of that has to be designed in before excavation. None of it can be added afterwards.

Energy and running cost

Below ground, the surrounding earth moderates the temperature. A properly insulated basement is cheaper to heat than the equivalent floor above it. It does need designed ventilation and a maintainable drainage and pump arrangement. That is where badly built basements fail.

Getting it right

A basement is a structural, planning and neighbour problem before it is an interior. Before you appoint anybody, read the ten checks worth making. Also read planning a basement conversion for the surveys and the sequence.

NU Projects builds basements in West London. It takes the planning, the party wall process and the structural design. It also takes the waterproofing and the fit-out, all through one contract. Tell us about the house.