Extension Cost · Richmond

How much does an extension cost in Richmond?

Richmond sits toward the top of the national range, and for two reasons at once — London-fringe labour, and a housing stock that is overwhelmingly period. A single-storey rear here runs from a shell figure around £3,930 per m² to an all-in nearer £6,470, and older or conservation-area properties push higher again.

Cost your Richmond extension See a sample report

The figure you find isn't the figure you pay

As everywhere, most Richmond cost guides quote a shell rate — the bare build. It is not what lands on your account. Calibrated to Richmond, 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 Richmond, 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, plus the period and conservation premium Richmond carries. Where in that range you land depends heavily on the property.

Richmond 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. Period and conservation-area properties sit toward and beyond the upper end.

Why Richmond sits above the national range

Two forces push Richmond costs up, and they compound. The first is labour: Richmond's project density and the pay scales across south-west London pull skilled trades toward the postcodes that pay best, so the same work costs more here than in most of the country. The second, and the larger one, is the housing stock itself.

Period stock is the dominant driver

Most of Richmond's housing is Victorian, Edwardian or interwar, and period property carries an overhead that newer builds do not. Lath-and-plaster comes down rather than being skimmed over. Joist depths often need packing or doubling to accept modern services. Lead and asbestos testing needs budgeting upfront rather than discovering mid-job. Chimneys and original windows frequently need specialist work rather than an off-the-shelf swap. None of it is exotic, and all of it is predictable once the property is properly assessed — but it is rarely in the headline figure people arrive with.

Conservation status adds cost before site work starts

Significant parts of Richmond sit within conservation areas, with pockets under further designation. Window specifications, materials and external alterations that pass freely elsewhere need formal application and design iteration here. Planning fees, additional drawings and conservation requirements are a real line item before a single course of bricks is laid.

The finishing trades are where the premium shows

Richmond properties tend to expect a standard of finish that demands experienced trades rather than fast ones. Tilers, joiners and decorators command a premium, and the work cannot be sped up without the quality showing. It is the most visible place the local labour premium lands.

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 Richmond calibration of it.

Extension cost — the full breakdown →

Common questions about extension cost in Richmond

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

Calibrated to Richmond, 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, with period and conservation-area properties toward and beyond the upper end. The figure depends heavily on the specific property, which is what a desktop analysis of your address sets out.

Why are Richmond extension quotes higher than the national average?

Two reasons that compound. Labour across south-west London is dearer, so the same build costs more. And Richmond's housing is overwhelmingly period, which carries a real cost overhead — lath-and-plaster, joist work, lead and asbestos testing, conservation-grade windows — that a national average never accounts for. The quote is usually not high; the national figure was incomplete for a period property in Richmond.

Does conservation-area status add to the cost of an extension in Richmond?

Yes. Much of Richmond sits within conservation areas, where external alterations, window specifications and materials need formal application and design iteration. That means planning fees, additional drawings and conservation requirements as real line items before site work begins — and it can rule some alterations out entirely. It is one of the reasons Richmond figures sit toward the top of the range.

What pushes a Richmond extension over budget?

The property and the fit-out, usually. Period surprises — joist depths, services, structural fabric that needs more work than expected once opened up — and a kitchen or bathroom specified above the budget it was set against. Both are predictable once the specific property is assessed, which is exactly what a BuildLens report does before you commit.