Extension Cost · Greenwich

How much does an extension cost in Greenwich?

Greenwich sits toward the top of the national range, with Victorian terraces doing the volume and a World Heritage setting sharpening the oversight near the centre. A single-storey rear here runs from a shell figure around £3,930 per m² to an all-in nearer £6,470.

Cost your Greenwich 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 Greenwich, 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 Greenwich, 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.

Why Greenwich sits above the national range

Greenwich pairs standard London cost drivers — labour and period stock — with a heritage setting few boroughs share.

A World Heritage setting sharpens oversight

Maritime Greenwich is a World Heritage Site, and its buffer zone reaches into the surrounding streets. Near the centre, rear elevations, rooflines and materials are watched more closely than the London norm, and applications iterate accordingly. Further out the controls relax to standard conservation coverage — west Greenwich in particular — but the gradient is real and it prices.

Victorian terraces do the volume

The working stock is Victorian terrace, and the working project is the rear knock-through with or without a side return. Party wall matters are near-standard, access is often through the house, and the period fabric carries the usual overhead of lath-and-plaster, joist work and services renewal.

The finishing premium follows the postcode

Greenwich finish expectations track its property values, and the experienced trades that deliver them price accordingly.

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 Greenwich calibration of it.

Extension cost — the full breakdown →

Common questions about extension cost in Greenwich

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

Calibrated to Greenwich, 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 Greenwich 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 Greenwich: heritage oversight that sharpens toward the centre, and the period overhead the terrace stock always carries. The quote is usually not high; the headline was incomplete for this property in this place.

Does the World Heritage Site affect extension cost in Greenwich?

Near the centre, yes. The buffer zone around maritime Greenwich means closer scrutiny of rear elevations, rooflines and materials than standard conservation coverage, with the design iteration and programme that implies. The effect fades with distance — much of the borough builds under ordinary conservation or none — but for addresses near the core it is a real line item.

What pushes a Greenwich 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.