Kitchen Extension Cost · 2026

How much does a kitchen extension cost?

A kitchen extension is one fixed build with a kitchen sitting on top of it. On a typical 30 m² kitchen-diner rear in the South East, the total runs from around £136,000 with a self-managed kitchen to £188,000 and beyond for a bespoke one. The build — including the knock-through steel — barely moves. The kitchen you choose is the whole difference.

Cost your kitchen extension See a sample report

One build, four budgets

Two costs make up a kitchen extension, and they behave completely differently. The build is fixed — shell, structure, services, finishes, and the knock-through steel that defines it. The kitchen is a choice, and it is the entire variable. For a representative 30 m² kitchen-diner rear, the total climbs like this while the base underneath never moves.

01 — Self-managed

Self-managed kitchen

IKEA, self-fit
£8,000 – £10,000

Project total £136,000
– £138,000

02 — Supplied & fitted

Supplied & fitted kitchen

Howdens · Magnet · Benchmarx
£14,000 – £22,000

Project total £142,000
– £150,000

03 — Premium

Premium kitchen

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

Project total £151,000
– £178,000

04 — Luxe & bespoke

Luxe & bespoke kitchen

deVOL · Tom Howley · Plain English
£60,000+

Project total £188,000+

The fixed build base £4,255/m² · ~£128,000 on a 30 m² rear

Identical on every rung — the kitchen moves, the build doesn't.

Foundations and slab · walls and superstructure · roof · envelope and glazing · first-fix services · non-kitchen finishes · fees and contingency · and the one thing that defines a kitchen extension: the structural knock-through — the steel and the opening between the existing house and the new room.

Self-managedLuxe & bespoke

Bespoke isn't the top rung. A local cabinetmaker builds you a bespoke kitchen at Premium money. The jump to the top buys the brand name — deVOL, Tom Howley, Plain English — and, usually, a bigger room to put it in.

South East figures on current trade day rates and live merchant pricing (2026), fully loaded — fees, contingency and VAT included. The build base is fixed for the extension; only the kitchen changes between rungs. Totals scale with size, and firm to your own property and region with a report.

What makes it a kitchen extension, not just an extension

The defining feature is the join. A kitchen extension almost always opens the new room into the existing house — a wall comes out, and a steel beam goes in to carry what that wall was holding up. That knock-through is on the base of every rung above, and it is the single element a plain new-kitchen page never has to price.

It carries its own considerations. The beam needs sizing and building-control sign-off, the opening needs making good on both sides, and if the wall sits on or near a boundary the work can trigger a party wall matter with the neighbour. None of it is exotic, and all of it is predictable once the specific property and the proposed opening are assessed — which is what a desktop analysis of your address is for.

Does location change the cost?

Yes, but less than for a bare extension — and the reason is instructive. The build follows local labour, so it moves region to region. The kitchen is mostly supply, and a Howdens or a deVOL costs much the same in Leeds as in London. A kitchen extension is one of each, so the region-flat kitchen dilutes the swing on the total.

Prime London +25–30%

South East & Kent baseline

Northern England −15–18%

Regional variation applies to the build, not the kitchen. So where a bare extension swings roughly a fifth either side of the South East across the country, a kitchen extension's total swings less — the further up the kitchen ladder you go, the more the region-flat kitchen flattens the regional spread. Figures rounded; BuildLens calibrates each to the property's location.

How BuildLens gets the number

A BuildLens figure is built from two layers, then calibrated to your property — its region, its age and type, and the scope of what you are building.

Layer 01 — Method

Itemised the way a job is actually priced

The build and the kitchen are broken out separately and by trade — substructure, superstructure, roof, envelope, services, the knock-through, then the kitchen fit-out on top. That separation is exactly why the total is a range: the build is fixed, and the kitchen line is where it moves.

Layer 02 — Current prices

Live rates, not a published average

The figures come from working trade day rates and weekly merchant pricing, refreshed continuously rather than pulled from an annual index. Location, property age and kitchen tier are applied on top, so the number reflects your project now — not a national mean from a guide last updated a year ago.

Common questions about kitchen extension cost

How much does a kitchen extension cost in 2026?

On a representative 30 m² kitchen-diner rear in the South East, the fully-loaded total runs from around £136,000 with a self-managed kitchen, through roughly £142,000–£150,000 for a supplied-and-fitted mainstream kitchen, to £151,000–£178,000 for a premium or local-bespoke one, and £188,000 and beyond for a named bespoke maker. The build base is fixed at about £128,000; the kitchen you choose sets where the total lands.

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 — tens of thousands of pounds 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.

Does a kitchen-diner knock-through need a steel beam?

Almost always. Removing a wall between the existing house and the new room means something has to carry the load above it, and that is usually a steel beam on padstones, sized by a structural engineer and signed off under building control. If the wall is on or near a boundary, the work can also trigger a party wall matter with the neighbour. It is a standard part of a kitchen extension, and it is carried in the fixed build base.

Does where I live change a kitchen extension's cost?

Less than for a bare extension. The build follows local labour and moves region to region — roughly 15–18% below the South East across much of the north, and 25–30% above in prime London. The kitchen, being mostly supply, costs much the same everywhere, so it dilutes the regional swing on the total. BuildLens calibrates every figure to the property's location.

Is a bespoke kitchen worth it in an extension?

It depends what you are buying. A local cabinetmaker builds you a genuinely bespoke kitchen at premium money. A named maker such as deVOL or Tom Howley costs several times more, and much of that premium is the brand and the scale of kitchen those makers typically fit rather than the cabinetry alone. In an extension the kitchen is the point of the project, so the decision matters more here than almost anywhere — which is exactly why it pays to set the tier before the build starts.