Extension Cost · Kilburn

How much does an extension cost in Kilburn?

Kilburn prices with its neighbours, whatever the purchase ledger says — the same trades that build in West Hampstead and Queen's Park build here, at the same rates. A single-storey rear runs from a shell figure around £3,930 per m² to an all-in nearer £6,470, and the gap between NW6's build cost and its buy-in price is exactly why the area is moving.

Cost your Kilburn 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 Kilburn, a single-storey rear looks like this per square metre.

The headline
you find

£3,930

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

What you
actually pay

£6,470

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

On a typical 30 m² rear in Kilburn, that is roughly £190,000 to £215,000 all-in — against a shell headline nearer £120,000. 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 calibrated from BuildLens South East build data — around 10% above the regional baseline — priced on current 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 Kilburn

Kilburn's cost story is the inverse of its neighbours': the constraint is lighter, the labour is identical, and the arithmetic is what makes the area work.

A market moving street by street

NW6 sits between West Hampstead and Queen's Park, and its Victorian terraces are being upgraded one street at a time. The build labour serving those streets is the same pool serving the neighbours — the day rates do not know which side of the postcode boundary they are on. What differs is the purchase base underneath, which is why extension arithmetic works harder here than almost anywhere in London.

Fewer heritage constraints than the neighbours

Kilburn carries less conservation coverage than the postcodes around it, which means more headroom under permitted development and faster, cheaper consents where full applications are needed. It is a genuine saving — in programme and fees, not in build cost.

The stock is honest Victorian terrace

The period overhead is the standard one: lath-and-plaster, joist work, services renewal, party wall awards on both sides. Predictable once assessed, and priced in the build base.

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 Kilburn calibration of it.

Extension cost — the full breakdown →

Common questions about extension cost in Kilburn

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

Calibrated to Kilburn, the shell runs around £3,930 per m² and the all-in — with a fitted kitchen, fees, contingency and VAT — nearer £6,470. A typical 30 m² rear therefore lands roughly £190,000 to £215,000 all-in. The figure depends heavily on the specific property, which is what a desktop analysis of your address sets out.

Why do Kilburn 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 Kilburn: the same period overhead as the neighbours, bought against a lower purchase base. The quote is usually not high; the headline was incomplete for this property in this place.

Is it cheaper to build an extension in Kilburn than West Hampstead?

Not meaningfully. The trades are the same pool at the same day rates, and the terrace fabric is the same Victorian stock. What Kilburn offers is a lower purchase base under the same build cost, plus lighter conservation coverage — faster and cheaper consents, not a cheaper build. The saving is in the arithmetic of the whole move, not the construction line.

What pushes a Kilburn 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.