Kitchen extension cost in 2026: build, kitchen and glazing
4 min
7
September 2026. Costs are indicative 2026 UK ranges, not a quotation.
Key figures in this guide
One-minute decision
What are you trying to work out?
Use the calculator with your own quantities and rates, then keep a contingency visible from day one.
Open calculatorA kitchen extension costs £52,000 - £86,000 in 2026 for a standard 20 square metre single-storey rear extension, £34,000 - £52,000 for a small 12 square metre one, and £78,000 - £130,000 for a wrap-around side return and rear. The shell alone is £2,300 - £3,400 per square metre; the kitchen and the glazing are separate budgets.
A kitchen extension is really three budgets pretending to be one: the shell, the kitchen itself, and the glazing. Most overspends happen because people price the shell and then discover the other two.
All figures are 2026 UK prices including labour and materials, excluding VAT where it does not apply and excluding furniture.
What a kitchen extension costs in 2026
| Scope | Size | Typical 2026 cost |
|---|---|---|
| Small rear extension, basic finish | 12 sq m | £34,000 - £52,000 |
| Standard single-storey rear, mid finish | 20 sq m | £52,000 - £86,000 |
| Wrap-around side return and rear | 28 sq m | £78,000 - £130,000 |
| Rear extension plus knock-through and structural beam | 20 sq m | £62,000 - £98,000 |
As a rate, the shell costs £2,300 - £3,400 per square metre in 2026. London and the South East run 15-30 per cent above the national figure.
The three budgets
| Element | Typical 2026 range | What drives it |
|---|---|---|
| Shell and structure | £2,300 - £3,400 per sq m | Ground conditions, drainage, steel spans |
| Kitchen supply and fit | £9,000 - £38,000 | Units, worktop material, appliances |
| Glazing | £4,000 - £26,000 | Rooflights, bifolds or slim-frame sliders |
Worktops alone move the number more than people expect: laminate £600 - £1,400, quartz £2,800 - £5,500, sintered stone or granite £3,500 - £7,500 for a typical run with an island.
What is usually extra
| Item | Typical 2026 cost |
|---|---|
| Architect or designer | £3,000 - £9,000 |
| Structural engineer | £750 - £1,800 |
| Planning application, where needed | £258 householder fee, plus drawings |
| Building control | £700 - £1,500 |
| Party wall surveyor, per neighbour | £1,200 - £2,200 |
| Underfloor heating | £3,000 - £6,500 |
| Moving or upsizing the drainage run | £1,500 - £5,000 |
| Redecorating the rooms you opened up | £1,500 - £4,000 |
What moves the price most
- 01Structural openings. A wide flush beam between the old and new space costs far more than a smaller opening with a downstand.
- 02Glazing choice. Slim-frame sliding doors can cost three times a standard bifold of the same width.
- 03Drainage and manholes. Building over a shared sewer needs approval and often a rebuild of the run.
- 04Ceiling height and rooflights. Flat roofs with several rooflights need more structure and more careful detailing.
- 05Where you live. Labour rates and access difficulty in cities are the single biggest regional factor.
How long it takes
- Design and approvals: 10-16 weeks
- Build on site: 12-20 weeks for a standard rear extension
- Kitchen fit and snagging: 3-5 weeks, once the shell is watertight and dry
How to get comparable quotes
Kitchen extension quotes rarely differ by skill. They differ by what has been assumed. Before asking for prices, write down:
- 01The finished floor area and the size of the structural opening.
- 02The glazing type, size and brand you are pricing.
- 03The kitchen budget, and whether the builder or a separate supplier fits it.
- 04The floor finish, heating type and lighting plan.
- 05Who pays for skips, scaffolding, protection and making good.
Renovome turns that into a defined brief and programme, so every professional prices the same job and you can compare like with like.
Related guides
- How much does a house extension cost, and how do you set a realistic budget?
- Extension cost calculator: how to work out your build cost per square metre
- Do I need planning permission for my extension or renovation?
Last reviewed: September 2026. Costs are indicative 2026 UK ranges, not a quotation.