Thinking about digging down to add more space to your home? Chris Bates takes a look at some of the most common questions about planning and building a basement extension 

 Natural lighting needs careful thought in a basement extension. In this project by Riach Architects, a structural glass balustrade allows brightness from two large rooflights on the storey above to flood into the new zone

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asements are a standard feature of new homes across the USA and much of Europe, yet they’re relatively rare here in Britain. That’s a real shame because, as I know first-hand from project managing Build It’s Self Build Education House, a wellplanned and well-lit basement can be a wonderful addition to a home – offering valuable and flexible extra living space.

Integrating this kind of zone into a self build project on a blank plot is one thing, of course, but what if you want to create one beneath an existing house? Well, improved construction and waterproofing techniques (and more designers and builders with experience delivering projects on the ground) mean it’s easier than ever to add a highquality basement extension. Here’s what to consider when deciding whether this is the right project for you.

What does a basement extension cost?

This will depend on the nature of your project and the scale of works required – not to mention the level of fit-out you’re going for. After all, some people choose to spend more on their home cinema than others do on the entirety of the internal fixtures and fittings.