How much does a kitchen extension cost in the UK?

A kitchen extension costs £71,400 to £103,000 including VAT across most of the UK for a 20 square metre single-storey build, or £90,400 to £144,000 in London. That figure splits into two separate budgets: the extension itself, and the kitchen that goes into it. Most published figures only price one of them.

That is the main reason kitchen extension quotes come in higher than people expect. A builder prices the box. A kitchen supplier prices the kitchen. Neither number is your project.

What does a kitchen extension cost in 2026?

At 30 square metres the build scales roughly with the floor area while the kitchen does not, because a bigger room does not necessarily mean more units. Expect £79,000 to £119,000 for the build nationally and £108,000 to £180,000 in London, with the kitchen figure largely unchanged.

The kitchen column does not vary by region because cabinetry, worktops and appliances come from national suppliers at national prices. It is the building work that carries the London premium.

What does the kitchen itself cost?

This is the half we can be precise about. The figures below come from 1,460 Beams kitchen projects estimated between January and July 2026, covering units, worktops, appliances, flooring, tiling and lighting. They exclude building work entirely.

Half of all kitchens land between £18,398 and £24,019. One in ten comes in below £13,543, and one in ten passes £26,320.

Those are medians and quartiles rather than averages, because a handful of very large projects would otherwise pull the figure up. Our projects are in London and the surrounding area, and the kitchen figures are used here as a national proxy on the basis that the goods are nationally priced.

If you want the kitchen figure broken down by layout and by component, our guide to what a kitchen renovation costs goes further, including what changes when you add an island.

What does the extension build cost?

Between £2,640 and £3,960 per square metre including VAT across most of the UK, and £3,600 to £6,000 in London, for a finished shell: foundations, walls, roof, glazing, plastered, wired, plumbed and floored, ready for the kitchen to go in.

A shell on its own, without any of that fit-out, runs £1,200 to £1,700 per square metre before VAT, against £2,200 to £3,300 for the same area finished on the same basis. Roughly half. That shell figure is sometimes quoted as an extension cost, which is how a project appears to double between the first conversation and the first quote.

The build is where the variables live: groundworks you cannot see until you dig, the width of the structural opening back into the house, and how much of the wall you want to be glass. Our guide to what a house extension costs covers the build side properly, including the statutory fees, the party wall position and the other extension types.

Where the kitchen budget actually goes

Three choices move the kitchen figure more than everything else combined.

Cabinetry. The widest range of anything in the project. Flat-pack at the bottom, rigid trade units in the middle, and hand-built joinery at the top, where the kitchen can cost more than the rest of the fit-out put together. This is where a £15,000 kitchen becomes a £40,000 one without the room changing at all.

Worktops. Laminate to quartz to Dekton swings several thousand pounds across an identical run of units. An island doubles the templated area, which is why it costs more than the unit itself suggests.

Appliances. The easiest place to overspend late, because a Bosch or Neff package sits at a very different level from a Miele or Gaggenau one, and the model in the showroom is rarely the base model.

Two things people expect to matter and mostly do not: the sink and the tap. Even a boiling-water tap is a few hundred pounds against a project measured in tens of thousands.

Does a bigger extension mean a bigger kitchen bill?

Not usually, and it is worth knowing before you size the build.

A kitchen's cost is driven by how many units you buy, not by how much floor you have. Going from 20 to 30 square metres adds around £26,000 of building work nationally and up to £60,000 in London, and often adds nothing at all to the kitchen, because the extra space becomes dining or seating rather than more cabinetry.

So if your motivation is a better kitchen, the cheaper route is a smaller extension with more of the budget in the fit-out. If it is space to eat and live in, extend further and keep the kitchen modest. Attempting both at maximum specification is how kitchen extensions reach six figures.

For narrow terraces where the footprint is fixed by the plot, our guide to small kitchen extension ideas covers what works in the space available.

The fees on top

Planning, building control, structural engineer, party wall and design fees together add somewhere between 5% and 24% on top of the build cost, with the architect appointment deciding where in that range you land. A householder planning application in England costs £548 from 1 April 2026, though many single-storey rear extensions fall within permitted development and need no application at all.

Those apply to any extension rather than to kitchen extensions specifically, and the house extension guide linked above sets each of them out with the current figures.

Separately from fees, hold 10% to 15% back as contingency. Older properties tend to need the higher end of that, because the ground and the existing structure are where the surprises live.

Do you pay VAT on a kitchen extension?

Yes, 20%, on both the building work and the kitchen. Every figure on this page includes it.

Extending an occupied home is standard-rated and no relief applies. The reduced 5% rate exists for renovating a property empty for two years or more, and for conversions that change the number of dwellings, and an extension does not qualify on its own. If a quote looks low, check for a missing VAT line before assuming otherwise.

One detail specific to the kitchen half, for the rare job where a reduced rate does apply: fitted kitchen furniture counts as a building material for VAT purposes, so the units qualify. Appliances do not, so the oven stays at 20% whatever the rest of the job is rated at.

How long does a kitchen extension take?

Ten to sixteen weeks on site for the build, then the kitchen fit on top, which adds two to three weeks once the shell is watertight and the floor is down.

Start to finish is longer than either. Design, planning and building control sit in front of the build, and kitchen lead times run six to twelve weeks for anything semi-bespoke. Order the kitchen while the foundations are going in, not when the plastering is done. Six to nine months from first drawing to cooking in it is realistic.

Does a kitchen extension add value?

Nationwide's house price research, based on its own mortgage lending, found that a 10% increase in floor space adds around 5% to a property's price, and that an extension delivering both an extra bedroom and a bathroom adds up to 24%.

A kitchen extension usually delivers neither of those. It adds ground-floor area and improves the room buyers judge a house on, which is worth having, but it rarely changes how the property is described in a listing. Treat it as something you are doing for the years you live there, with a reasonable chance of recovering much of the cost, rather than as an investment. Over-specifying for the street is how people lose money on one.

How Beams helps

A kitchen extension is two projects that have to be sequenced as one. The kitchen has to be designed before the shell is finished, because the services, the floor build-up and the ceiling heights all depend on it. Get that order wrong and you spend the build chasing changes.

So we define both halves up front: the build scope and the kitchen specification. Then we set a realistic cost expectation, match you with builders suited to the job, and line up as many as three site visits, all quoting from the same information.

That is what a managed kitchen renovation with Beams looks like: one agreed price, payments released against milestones, and a 12-month workmanship warranty behind it.

Common questions about kitchen extension costs

Can I get a kitchen extension for £50,000?
Not at 20 square metres. On these figures the build alone starts at £53,000 nationally before any kitchen goes in. It becomes possible on a smaller footprint, around 12 to 15 square metres, with a straightforward specification and a kitchen at the lower end of the range. In London it is out of reach at any size once VAT is counted.

Should I buy the kitchen separately from the builder?
You can, and it often saves the builder's margin on the units. You take on the risk of ordering the wrong sizes for a room that does not exist yet, which is a real risk on a new shell where dimensions move during the build. Agree who measures, and at what point.

Does the kitchen have to be finalised before the build starts?
Close to it. The position of the sink, the hob and the extractor determine where services run, and the choice of flooring determines the floor build-up, so both need deciding before first fix. You can leave door colours and handles late. You cannot leave the layout late.

Do I need planning permission?
Often not. Many single-storey rear extensions fall within permitted development, subject to depth, height and boundary limits, and to the property not being listed or in a conservation area. A Lawful Development Certificate for a proposed use costs £274 if you want that confirmed in writing.

Where these figures come from

The kitchen figures come from 1,460 Beams kitchen projects estimated between January and July 2026, covering units, worktops, appliances, flooring, tiling and lighting at retail price. They include VAT and are stated as medians and quartiles rather than averages. Our projects are in London and the surrounding area.

The extension build figures are market rates rather than Beams data, compiled from published industry cost sources: Architecture for London (London £3,000 to £5,000 per m², construction only, ex VAT, January 2026), Homebuilding & Renovating (£2,200 to £3,300 per m² finished, ex VAT, February 2026) and Checkatrade (shell only £1,200 to £1,700 per m², ex VAT). Inc-VAT figures are calculated at 20%.

Planning and certificate fees: Planning Portal, applying from 1 April 2026

Building control: published council fee schedules, 2025 and 2026

Value uplift: Nationwide house price research, October 2025

Professional fee ranges: HomeOwners Alliance, 2026. RIBA publishes no fee percentage

Every project prices differently once the ground, the structure and the kitchen specification are known. These figures are a starting point for a conversation rather than a quote.