How Much Does a Kitchen Extension Cost in 2026? (UK)
A kitchen extension in the UK costs £35,000 to £75,000 in 2026, covering the extension shell and the kitchen fit-out. It's the UK's most popular home improvement — and adds significant value. Here's the full 2026 cost breakdown.
Kitchen extension cost at a glance
A typical kitchen extension in the UK in 2026 costs £35,000–£75,000 — broken down as roughly £1,800–£2,500/m² for the build and £8,000–£30,000 for the kitchen itself.
- Small kitchen extension (15m²): £35,000 – £50,000
- Medium kitchen extension (25m²): £50,000 – £75,000
- Large kitchen-diner extension (40m²): £75,000 – £110,000
- Side return extension (London terraces): £45,000 – £70,000
London and the South East typically add 20–25%. A kitchen extension adds 10–18% to UK property value — often more than the build cost on properties above £400,000.
2026 Kitchen Extension — Shell + Fit-Out Split
A kitchen extension has two parts: the extension itself (shell) and the kitchen (fit-out). Most homeowners underestimate the fit-out cost. Here's a realistic 2026 split.
| Element | Budget Spec | Mid-Range | High-End |
|---|---|---|---|
| Extension shell (20m²) | £36,000 | £45,000 | £55,000 |
| Kitchen units & worktops | £5,000 | £12,000 | £25,000 |
| Appliances | £1,800 | £4,500 | £10,000 |
| Flooring (LVT / tile / engineered wood) | £1,200 | £2,400 | £4,800 |
| Bifold / sliding doors | £3,500 | £6,500 | £12,000 |
| Lantern / skylights | £0 | £2,500 | £6,000 |
| Underfloor heating | £0 | £1,800 | £3,500 |
| Total (20m² kitchen extension) | £47,500 | £74,700 | £116,300 |
Prices include all labour, materials, building control and VAT. Add 10% contingency. Regional variation: +25% London, −10% to −15% North England, Wales and Scotland.
Kitchen Extension Types & 2026 Prices
Build onto the back of the house to create an open-plan kitchen-dining space. Usually under Permitted Development. The gold standard for UK family homes.
Extends into the unused side passage. Transforms dark Victorian kitchens into bright, wide open-plan spaces. Typical 5–6m² uplift.
Rear + side combined. Creates the largest open-plan kitchen-living space possible on a single floor. Planning usually required.
Generic single-storey rear extension used for a new kitchen. Flat roof or pitched, with glazing to the garden.
Kitchen-diner downstairs plus an extra bedroom or ensuite above. Best value per m² — shares foundations and roof with existing house.
Solid-roof orangery or conservatory extension. Usable year-round with underfloor heating. Limits kitchen layout flexibility.
How to Save £5,000–£15,000 on a Kitchen Extension in 2026
Kitchen extensions are where budgets most often slip. Here are six specific moves that save UK homeowners thousands in 2026 without compromising the finished result:
- Get 3 quotes, not 1. Prices vary 20–30% between builders for identical specs — a £60,000 job can come in at £48,000 from a different quote. Free to do, saves thousands.
- Stay within Permitted Development. Avoid a £258 planning fee plus £2,000–£4,000 of architect resubmissions. PD also saves 8–12 weeks of project time.
- Choose flat roof over pitched. A GRP or EPDM flat roof is £3,000–£6,000 cheaper than a pitched roof for the same footprint — and modern finishes look sharp.
- Skip the roof lantern. Lanterns add £3,000–£6,000. Two well-placed Velux rooflights give similar daylighting at a third of the cost.
- Supply your own kitchen. Buying units direct from Howdens/Wren/Magnet and asking your builder to install can save £3,000–£8,000 vs a turnkey kitchen specialist.
- Time the build for spring. January–March is builder low season — expect 5–10% lower quotes. Avoid October–December when everyone wants work done before Christmas.
More Kitchen & Extension Guides
All cost guides →Full guide to rear extension costs by size with regional data.
Loft conversion costs by type — Velux, dormer, hip-to-gable, mansard.
Costs for a new kitchen without extending — units, worktops, fit.
Vetted kitchen fitters and builders — free quotes in 24 hours.