How much does a house extension cost in Surrey?

This is one of those questions that comes up early on and quite rightly so. Whether you’re planning a side return, a rear extension, or a full double-storey addition, understanding the cost is key to knowing what’s realistic for your home and budget.

The truth is, costs vary a lot, but the more you understand the moving parts, the easier it is to plan with confidence and avoid the “hidden extras” that can creep in if you’re not prepared.

As a very general guide, in Surrey, a single-storey extension tends to start around £2,500 - £3,000 per square metre, depending on the level of finish, the materials you choose, and the complexity of the build. Double-storey extensions usually offer better value per square metre, but of course, they require more upfront investment. These are just ballpark figures though, and the real number depends on so many details, from the size and style of your extension to the specifics of your site.

And yes, where you live within Surrey does matter. Some areas have higher labour and material costs than others, and things like access (tight driveways, terraced houses, conservation areas) can also affect how straightforward (or not) the build will be. Then there are the choices that affect cost: bespoke glazing vs. standard windows, timber cladding vs. brickwork, polished concrete floors vs. laminate… each decision plays its part.

What’s easy to overlook are the softer costs: planning applications, building regulations approval, structural engineers, party wall surveyors (if your project’s close to a neighbour), and of course, those three magical letters…VAT. These aren’t the glamorous bits of a project, but they do add up, and they’re crucial to factor in early on!

In my experience, the best approach is to be open with yourself about your budget and your priorities. What really matters to you? Is it the big open-plan kitchen that’ll be the hub of family life? The light? More open access to the garden? When you’re clear on that, it’s much easier to design smartly and spend where it counts.

The cost of extending is rarely a small thing, but when it’s done thoughtfully, it can be one of the best investments you make - not just in your property, but in how you live every day. And if you're in the early stages and feeling unsure, don’t be afraid to start a few conversations with contractors. The clearer your picture from the beginning, the smoother your project will go!