Kitchen Extension Cost · Chiswick

How much does a kitchen extension cost in Chiswick?

A kitchen extension is one fixed build with a kitchen sitting on top of it, in Chiswick that usually means a side-return infill with a long steel span. Calibrated to Chiswick, a typical 30 m² kitchen-diner rear runs from around £148,000 with a self-managed kitchen to £200,000 and beyond for a bespoke one — the build barely moves, and the kitchen you choose is the whole difference.

Cost your Chiswick kitchen extension See a sample report

One build, four budgets — calibrated to Chiswick

The build is fixed; the kitchen is the variable. For a representative 30 m² kitchen-diner rear in Chiswick, the project total climbs with the tier while the base underneath never moves.

Self-managed IKEA, self-fit
£8,000 – £10,000 £148,000 – £150,000

Supplied & fitted Howdens · Magnet · Benchmarx
£14,000 – £22,000 £154,000 – £162,000

Premium Local bespoke · Second Nature / Burbidge
£23,000 – £50,000 £163,000 – £190,000

Luxe & bespoke deVOL · Tom Howley · Plain English
£60,000+ £200,000+

The fixed build base — £4,680/m² · ~£140,000 on a 30 m² rear. Foundations and slab, walls and superstructure, roof, envelope and glazing, first-fix services, non-kitchen finishes, fees and contingency — and the structural knock-through, the steel and the opening between the existing house and the new room. Identical on every tier.

Figures calibrated from BuildLens South East build data — around 10% above the regional baseline — priced on current day rates and live merchant pricing (2026). Fully loaded — fees, contingency and VAT included. Totals scale with size, and firm to your own property with a report. The full tier ladder, with what each rung buys, sits on the main kitchen extension page.

The knock-through in Chiswick

In Chiswick the kitchen extension is usually a side-return infill combined with a rear opening — which means a long steel span carrying two walls' worth of load, opened in one structural operation. It is the defining local project, and where a full rear extension joins it, the two are priced as two extensions rather than one.

The mechanics are the same everywhere: a wall comes out, an engineer-sized steel beam goes in to carry what it held, building control signs it off, and where the wall sits on or near a boundary, a party wall matter follows. All of it is standard, all of it is predictable from the property, and all of it is carried in the fixed build base — the tier ladder above sits on top of it, never inside it.

The full ladder, rung by rung. What each kitchen tier actually buys — and why bespoke is not the top rung — sits on the main kitchen extension page. This page is the Chiswick calibration of it.

Kitchen extension cost — the full ladder →

Common questions about kitchen extension cost in Chiswick

How much does a kitchen extension cost in Chiswick?

On a representative 30 m² kitchen-diner rear calibrated to Chiswick, the fully-loaded total runs from around £148,000 – £150,000 with a self-managed kitchen, through £154,000 – £162,000 supplied and fitted, to £163,000 – £190,000 for a premium or local-bespoke kitchen, and £200,000+ for a named bespoke maker. The build base is fixed at about £140,000; the kitchen tier sets where the total lands.

Is a side-return kitchen extension priced differently in Chiswick?

The side-return infill is its own scope — a long steel span, a glazed roof over the diner, and access through the house on most terrace streets. Where a side return is combined with a full rear extension, BuildLens prices them as two extensions, never one, because that is how the work actually builds.

Why does the kitchen choice change the total by so much?

Because the build behind it doesn't change. The structure, roof, envelope, services and the knock-through steel cost much the same whichever kitchen goes in — so the entire spread on the same extension sits in the kitchen tier. Picturing a bespoke kitchen on a mainstream budget is where most kitchen-extension budgets come apart.