Extension Cost · Beaconsfield

How much does an extension cost in Beaconsfield?

Beaconsfield prices at the South East baseline BuildLens builds from, in one of the highest-value towns in the commuter belt — and its projects behave accordingly, climbing on size and specification at once. A single-storey rear runs from a shell figure around £3,575 per m² to an all-in nearer £5,882, and Beaconsfield projects routinely leave that representative case behind.

Cost your Beaconsfield extension See a sample report

The figure you find isn't the figure you pay

As everywhere, most cost guides quote a shell rate — the bare build. It is not what lands on your account. Calibrated to Beaconsfield, a single-storey rear looks like this per square metre.

The headline
you find

£3,575

Shell only — structure, roof, envelope. Per m².

What you
actually pay

£5,882

All-in with a fitted kitchen, fees, contingency and VAT. Per m².

On a typical 30 m² rear in Beaconsfield, that is roughly £150,000 to £175,000 all-in — against a shell headline nearer £107,000. The difference is the fit-out, the professional fees, the contingency and the VAT the shell figure never included. Where in that range you land depends heavily on the property.

Figures at the BuildLens South East baseline, priced on current trade day rates and live merchant pricing (2026). The all-in assumes an entry-level bespoke kitchen from local joinery; a higher kitchen tier moves it further.

What moves the number in Beaconsfield

Beaconsfield's baseline rate conceals how far its projects travel from the baseline case.

Top of the commuter belt

Among the highest-value towns in the London orbit, Beaconsfield's specification expectations sit at the top of the market — the finishes, glazing and fit-out tiers that elsewhere mark a premium project are the local norm, and the trades that deliver them price for it.

Old Town and New Town

The Georgian coaching core of the Old Town carries conservation coverage and the period overhead; the New Town's Edwardian and later plots are generous, and generous plots take large extensions. Two stocks, two stories — one protected, one expansive.

Projects run large

Full-width rears, wraps and double-storey additions are the local pattern on the New Town plots. At the same per-square-metre rate, the footprints lift Beaconsfield totals well above the representative 30 m² case.

Where the money goes, itemised. The full anatomy of an extension — substructure through fit-out — and how BuildLens builds the number from method and live pricing, sits on the main extension cost page. This page is the Beaconsfield calibration of it.

Extension cost — the full breakdown →

Common questions about extension cost in Beaconsfield

How much does a single-storey rear extension cost in Beaconsfield?

Calibrated to Beaconsfield, the shell runs around £3,575 per m² and the all-in — with a fitted kitchen, fees, contingency and VAT — nearer £5,882. A typical 30 m² rear therefore lands roughly £150,000 to £175,000 all-in. The figure depends heavily on the specific property, which is what a desktop analysis of your address sets out.

Why do Beaconsfield quotes differ from the national averages online?

Because most published figures are shell rates without fit-out, fees, contingency or VAT — and because they know nothing about Beaconsfield: plots that take large footprints, and a local market that specifies at the top of every tier. The quote is usually not high; the headline was incomplete for this property in this place.

Why do Beaconsfield extension totals run above the South East figure?

Size and specification together. The labour prices at the South East band, but the New Town's plots take large extensions and the local market specifies at the top of it — so the same per-square-metre arithmetic lands on bigger footprints and higher tiers. The representative figure is the floor here, not the midpoint.

What pushes a Beaconsfield extension over budget?

The property and the fit-out, usually — a kitchen or bathroom specified above the budget it was set against, and the local conditions above surfacing mid-job instead of being priced upfront. Both are predictable once the specific property is assessed, which is exactly what a BuildLens report does before you commit.