Kitchen Extension Cost Breakdown: London Data (2026)
We analysed DesignForMe survey data covering thousands of kitchen extension projects across the UK. The London premium is real: a 10m² kitchen extension costs £109,000 in London versus £53,000 outside - a 2.06x multiplier.
TL;DR
Kitchen extensions in London cost roughly double what they cost elsewhere in the UK. A 10m² kitchen extension averages £109,000 all-in (London) versus £53,000 (non-London). The cost breaks down into three layers: structural build (£3,000/m² inner London), kitchen fit-out (£8,000-25,000+), and project costs (fees, VAT, contingency). The biggest variable is the kitchen itself - a basic kitchen adds £8,000, while a premium spec with stone worktops and integrated appliances pushes past £25,000. Builder day rates in London run £280-440/day, with specialist trades like electricians and plumbers even higher.
£109k
London 10m² average (all-in)
DesignForMe survey data
£53k
Non-London 10m² average
DesignForMe survey data
2.06x
London premium
London vs non-London ratio
£3,000/m²
Inner London build cost
Regional cost model
Sources: DesignForMe survey data, ConcreteMath trade rates 2024/25, Mayfair Studio cost model
The Headline Numbers
DesignForMe surveys thousands of homeowners who have completed extension projects across the UK. Their data for kitchen extensions of approximately 10m² shows a stark London premium:
- -UK average: £86,500 all-in for a 10m² kitchen extension
- -London average: £109,000 (26% above UK average)
- -Non-London average: £53,000 (39% below UK average)
- -London premium: 2.06x (London costs are more than double non-London)
These are all-in figures including build costs, kitchen, fees, VAT, and contingency. The London premium reflects higher land values (which push up builder costs), more constrained sites, higher specification expectations, and the additional complexity of working in a dense urban environment.
Kitchen Extension Cost by Size (London)
Costs scale with size, but not linearly. Larger extensions have a lower cost per m² because fixed costs (foundations, steelwork, connections) are spread over more area. Here are the typical all-in cost ranges for London kitchen extensions:
| Extension size | Cost range (London) | Cost per m² | Typical layout |
|---|---|---|---|
| 10m² | £65,000 - £95,000 | £6,500 - £9,500 | Compact kitchen or galley extension |
| 15m² | £85,000 - £120,000 | £5,700 - £8,000 | Kitchen-diner with island |
| 20m² | £110,000 - £155,000 | £5,500 - £7,750 | Open-plan kitchen-diner-living |
| 25m² | £135,000 - £190,000 | £5,400 - £7,600 | Large open-plan with utility |
Source: Mayfair Studio cost model, DesignForMe survey data • Data as of 2026
Ranges reflect variation between inner and outer London, standard vs premium specification, and site-specific factors. All figures include VAT, professional fees, and 10% contingency.
Build Cost Breakdown
The "build cost" is the structural construction before you add the kitchen, fees, or VAT. In inner London, this runs at approximately £3,000/m². Outer London is slightly lower at £2,600-2,900/m². Here's how a typical 15m² kitchen extension build cost breaks down:
| Component | Cost | % of build |
|---|---|---|
| Foundations and groundworks | £6,000 - £9,000 | 13-20% |
| Structural steelwork | £3,000 - £5,000 | 7-11% |
| Walls, brickwork, blockwork | £5,000 - £8,000 | 11-18% |
| Roof structure and finish | £4,000 - £6,000 | 9-13% |
| Windows and doors (inc. bifolds) | £5,000 - £10,000 | 11-22% |
| First fix (electrics, plumbing, heating) | £4,000 - £6,000 | 9-13% |
| Insulation and damp proofing | £2,000 - £3,000 | 4-7% |
| Plastering and second fix | £3,000 - £5,000 | 7-11% |
| Flooring | £2,000 - £4,000 | 4-9% |
| Decoration and snagging | £1,500 - £3,000 | 3-7% |
Source: Mayfair Studio cost model • Data as of 2024/25 rates
The total build cost for a 15m² extension at £3,000/m² is approximately £45,000. To reach the all-in cost, you add the kitchen (£8,000-25,000+), professional fees (10-15%), VAT (20%), and contingency (10%). This is why the all-in figure of £85,000-120,000 is roughly 1.9-2.7x the raw build cost.
Kitchen Specification Levels
The kitchen itself is often the single biggest variable in the project. The difference between a basic and premium kitchen can be £17,000+. Here's what each level typically includes:
| Spec level | Cost | Includes |
|---|---|---|
| Basic | ~£8,000 | Flat-panel doors, laminate worktops, freestanding appliances, standard sink and tap |
| Standard | ~£15,000 | Shaker-style doors, composite worktops, integrated oven and hob, undermount sink, better hardware |
| Premium | £25,000+ | Handleless or bespoke cabinetry, stone worktops (quartz/granite), fully integrated appliances, boiling water tap, feature lighting |
Source: Kitchen supplier pricing, Mayfair Studio project data • Data as of 2025/26
Most London homeowners investing in a kitchen extension opt for standard to premium specification. The logic is straightforward: if you're spending £50,000+ on the build, skimping on the kitchen undermines the whole project. Island units add £3,000-8,000 depending on size and complexity.
London Trade Rates (2024/25)
Understanding trade rates helps you assess builder quotes. These are day rates for London-based tradespeople from the ConcreteMath 2024/25 survey:
| Trade | Day rate (London) | Typical days on 15m² extension |
|---|---|---|
| General builder / labourer | £280 - £440 | 40-60 days |
| Electrician | £350 - £550 | 5-8 days |
| Plumber | £350 - £500 | 4-7 days |
| Tiler | £250 - £400 | 3-5 days |
| Plasterer | £300 - £450 | 4-6 days |
| Roofer | £300 - £450 | 3-5 days |
| Structural engineer | £400 - £600 | 1-2 site visits + calcs |
Source: ConcreteMath trade rate survey • Data as of 2024/25
These rates explain why London builds cost more. A builder charging £350/day for 50 days is £17,500 in labour alone, before materials, subcontractors, or overheads. Most builders quote a fixed price rather than day rates, but understanding the underlying labour costs helps you evaluate whether a quote is reasonable.
What Drives Cost Variation in London?
The wide cost ranges reflect real differences between projects. The main factors driving costs up or down:
- 1.Inner vs outer London. Inner London build costs are 15-25% higher than outer London due to site access constraints, parking restrictions, and higher trade rates. A 15m² extension in Islington will cost more than the same build in Bromley.
- 2.Structural complexity. Removing a load-bearing wall requires steelwork (£3,000-5,000). Underpinning existing foundations for a deeper dig adds £5,000-15,000. Party wall agreements cost £1,500-3,000 per neighbour.
- 3.Glazing choices. Bifold doors are the most popular choice for kitchen extensions but vary enormously in price. Aluminium bifolds range from £4,000-12,000 depending on size, brand, and thermal performance. Slim-frame systems like Schuco or Origin are at the top end.
- 4.Kitchen specification. As shown above, the kitchen itself can range from £8,000 to £25,000+. This single line item creates most of the variation in otherwise similar projects.
- 5.Heritage constraints. Conservation area requirements for matching materials, or listed building consent conditions, can add 30-50% to build costs. London stock brick matching alone can add £3,000-5,000.
Hidden Costs to Budget For
Beyond the build and kitchen, several costs are frequently underestimated:
| Cost item | Typical range | Notes |
|---|---|---|
| Architectural drawings | £2,500 - £5,000 | Planning + building regs drawings |
| Structural engineer | £800 - £1,500 | Beam calculations, foundation design |
| Party wall surveyor | £1,500 - £3,000 | Per neighbour, if party wall affected |
| Building control | £500 - £1,000 | Council or approved inspector fees |
| Planning application | £258 | Householder fee (2026), if needed |
| Thames Water build-over | £400 - £800 | If building over a public sewer |
| Skip hire and waste | £2,000 - £4,000 | 6-8 skips typical for kitchen extension |
| Temporary kitchen | £500 - £1,500 | 8-12 weeks without a kitchen |
| Contingency (10%) | £6,500 - £15,000 | Essential for unexpected issues |
Source: Mayfair Studio project data • Data as of 2024-2026
Frequently Asked Questions
How much does a kitchen extension cost in London?
A 10m² kitchen extension in London costs £65,000-£95,000 all-in, rising to £85,000-£120,000 for 15m² and £110,000-£155,000 for 20m². These figures include build costs, kitchen fit-out, professional fees, VAT, and contingency. Inner London is 15-25% more expensive than outer London.
Why are kitchen extensions so expensive in London?
London's 2.06x premium over the rest of the UK reflects higher trade rates (builders charge £280-440/day vs £180-280 outside London), constrained site access, parking restrictions, higher specification expectations, and the structural complexity of extending Victorian and Edwardian terraces. Our free AI chat gives you a cost estimate specific to your property.
How much does a kitchen cost for an extension?
The kitchen fit-out itself costs approximately £8,000 for a basic spec (flat-panel, laminate worktops), £15,000 for standard (shaker-style, composite worktops, integrated appliances), and £25,000+ for premium (handleless/bespoke, stone worktops, fully integrated). Most London homeowners choose standard to premium.
How long does a kitchen extension take to build?
A typical 15m² single-storey kitchen extension takes 10-14 weeks on site. Add 8-16 weeks for design, planning (if needed), and building regulations approval. From first architect meeting to moving back in, budget 6-9 months total.
Do I need planning permission for a kitchen extension in London?
Many kitchen extensions qualify as permitted development if they are single-storey, rear only, and within size limits (3m depth for semi/terraced or 4m for detached under standard PD; up to 6m or 8m respectively with Prior Approval). Conservation areas, Article 4 directions, and other constraints may remove PD rights. Use our free PD checker to find out instantly.
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