How Much Does a House Extension Cost in Bristol in 2026?

It is the first question every homeowner asks, and the one the internet answers worst. Search for extension costs and you will find figures ranging from suspiciously cheap to wildly high — usually written by people who have never built one.

As rough guidance only, a well-built single-storey extension in the Bristol area typically falls somewhere between £1,800 and £2,600 per square metre in 2026, with double-storey work often costing less per metre than single-storey because the foundations and roof are shared. Treat any figure like this as a starting point for a conversation, not a quotation — every house, plot and specification is different.

What actually moves the price: the ground beneath your house (poor ground means deeper foundations), the amount of structural steelwork needed to open up the existing rear wall, the glazing (slim-framed sliding doors and large rooflights are worth every penny, but they are not cheap), the kitchen and finishes you choose, and access — a tight Bristol terrace with no side access costs more to build on than an open suburban plot.

The costs people forget: design fees, structural engineering, planning or lawful development certificates, Building Regulations fees, party wall agreements in terraced streets, and VAT. A proper proposal should make all of this visible before you commit.

Our honest advice: be wary of any builder who gives you a firm price over the phone or from a photograph. A reliable figure comes from a site visit, a defined scope and an itemised proposal. That is exactly how we work — the initial consultation and site visit cost you nothing, and the detailed proposal tells you precisely what is and is not included.

If you are planning an extension in Bristol, Somerset or South Wales, request a consultation and we will give you a straight answer about what your project is likely to involve.