Cost guide · 2026
KitchenExtensionCostinLondon2026
Detailed pricing for London open-plan kitchen extensions: side return, rear, wraparound. Real-world cost ranges, factor analysis and worked examples.
Quick answer
A kitchen extension in London costs £55,000–£180,000 for the building work. A side return kitchen extension typically runs £55,000–£115,000; a 4m rear kitchen extension £75,000–£130,000; a wraparound kitchen-dining space £115,000–£180,000. Kitchen units and appliances are separate — typically £20,000–£55,000 extra. Cost per m² is £3,200–£4,800.
What moves the price
The seven cost factors that matter most.
Standard bifold £8–12k; premium slider £14–22k; steel Crittall £18–28k. Single biggest variable above 35m².
Howdens £8–18k; bespoke painted in-frame £25–45k; hand-built premium £45–80k. Excluded from base extension cost.
Quartz £350–£500/m²; Dekton £700–900/m²; marble £500–1,500/m² + maintenance cost.
Spine wall removal £4–7k per beam; opens kitchen to dining/living.
Mid-spec £6–9k; premium integrated (Miele, NEFF Slide&Hide) £14–25k.
Wet UFH £150–280/m²; electric £40–80/m². Adds 250mm build-up vs existing.
Layered design (ambient, task, feature, accent) on dimmable circuits £2,500–4,500 for typical kitchen.
Cost breakdown
Where the money actually goes.
Percentage breakdown of a typical mid-spec project. Add or subtract per your finish tier.
| Line item | % of total | £ on avg project |
|---|---|---|
| Groundworks & foundations | 12% | £14,100 |
| Superstructure & roof | 14% | £16,450 |
| Glazing | 14% | £16,450 |
| Electrics | 8% | £9,400 |
| Plumbing & heating | 7% | £8,225 |
| Plaster & decoration | 6% | £7,050 |
| Worktops | 6% | £7,050 |
| Flooring | 7% | £8,225 |
| Lighting & second fix | 4% | £4,700 |
| Fees | 9% | £10,575 |
| Site management | 6% | £7,050 |
| Margin & contingency | 7% | £8,225 |
Real projects
Worked examples from completed builds.
London zones
Where your borough sits in the price band.
| Zone | Multiplier | Notes |
|---|---|---|
| Zone 1–2 | 1.15–1.25× | Premium spec, access surcharges |
| Zone 3 | 1.00–1.08× | Baseline |
| Zone 4–6 | 0.90–1.00× | Outer boroughs |
Builderr vs other London builders.
The construction industry has a wide distribution of operators. Here's what changes between a directly-employed, fixed-scope outfit and the alternatives.
| Criterion | Builderr | Typical London builder | Cowboy outfit |
|---|---|---|---|
| Labour model | Directly employed team (PAYE) | Mixed subcontract gangs | Day-rate cash labour |
| Pricing | Fixed-scope itemised quote | Estimate + provisional sums | Verbal price + variations |
| Design & engineering | In-house architect + SE | Outsourced, separate billing | Builder draws on the back of an envelope |
| Planning + LDC handled | Yes — included in price | Often charged extra | Builder asks you to apply |
| Party wall surveyors | Instructed by us | Your responsibility | Skipped (illegal) |
| Building control | Plans + site inspections booked by us | Building Notice route | Not registered |
| Project management | Dedicated PM, weekly photo updates | Foreman doubles up | Owner-manager juggles 5 jobs |
| Payment schedule | Stage payments against signed-off milestones | Weekly invoices | Cash up front |
| Insurance | £10M PL + 10yr structural warranty | £2–5M PL only | No documented cover |
| Snags at handover | <3 typical | 20–30 typical | Walk-off mid-job common |
| Variation creep | 0% — fixed scope | +15–25% over original quote | +40%+ regularly |
Save £23,500–£52,875 on a kitchen extensions.
Industry data (FMB, RICS, Which? Trusted Trader 2024) shows the average London construction project overruns by 18–22% on cost and 25–35% on time. Fixed-scope contracts with a single accountable team eliminate that variance. The savings above assume a typical project at £117,500.
Related
See the full kitchen extensions service page.
FAQ
Kitchen Extension Cost in London:
common questions.
How much does a kitchen extension cost in London including the kitchen?
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A 4m rear kitchen extension with bifold doors and a mid-spec kitchen (Howdens or equivalent, quartz worktops, integrated appliances) typically costs £95,000–£140,000 all-in. A 6m rear with a bespoke kitchen runs £140,000–£200,000. A wraparound with a hand-built kitchen: £200,000–£260,000.
Is a kitchen extension worth the cost in London?
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For most London terraces in zones 2–4, yes. An open-plan kitchen-diner is now expected by buyers at the £700k–£1.5m level — properties without one sell more slowly and at a discount. A well-executed kitchen extension typically adds more value than it costs in inner London, particularly when it creates a through-room to the garden.
Why is a kitchen extension more expensive than a standard extension?
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Kitchen extensions cost more per m² because they involve: removing additional internal walls (spine wall between kitchen and dining room), upgrading the consumer unit for induction and appliance loads, installing UFH with full screed floor build-up, specifying premium glazing, fitting worktops (templated stone), and integrating all appliance connections. The glazing alone (bifolds + lantern) is often £18,000–£28,000.
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