UK extension costs · 2026
Kitchen extension cost in the UK (2026 prices)
A kitchen extension is a single storey extension plus a full kitchen fit-out, and usually plenty of glazing. The ranges below include a new kitchen, bifold or sliding doors and a roof lantern, which is what most homeowners actually want when they open up the back of the house.
Typical kitchen extension cost by size
| Size | Indicative cost |
|---|---|
| Compact kitchen extension (about 15 m²) | £40,000 – £51,000 |
| Kitchen-diner (about 25 m²) | £55,500 – £71,000 |
| Large open-plan kitchen (about 35 m²) | £71,500 – £90,500 |
| Full-width kitchen and family room (about 45 m²) | £87,000 – £110,500 |
Indicative only, based on typical UK build rates for a standard finish. Your own quote depends on your property, access and specification.
How much of the budget is the kitchen itself?
A mid-range fitted kitchen with appliances and worktops typically sits between £10,000 and £18,000, and can run far higher with stone worktops and premium appliances. Bespoke joinery can double it.
Because the kitchen is the most visible part of the project, it is worth fixing your kitchen budget early so the builder's quote and the kitchen supplier's quote add up to something you are comfortable with.
Glazing, ventilation and lighting
Deep kitchen extensions can feel dark at the back of the original house, so roof lanterns or slimline rooflights are usually money well spent.
Building regulations require adequate extraction in a kitchen — plan the cooker hood route early, because it affects where the hob can sit.
What affects the price most
- Floor area in square metres — the single biggest driver of the total price.
- Access to the rear or side of the property for machinery, deliveries and waste.
- Ground conditions, drainage runs, manholes and any nearby trees affecting foundation depth.
- Structural openings: a wide steel beam into the existing house costs more than a standard doorway.
- Glazing choice — bifold or sliding doors, roof lanterns and large windows add several thousand pounds.
- Internal fit-out: kitchens, bathrooms, underfloor heating, flooring and decoration.
- Professional fees: architect or designer, structural engineer, building control and any planning application.
- Where you are in the UK — London and the South East typically run 10–20% above national averages.
Frequently asked questions
- How much does a kitchen extension cost in the UK?
- Most kitchen extensions land between roughly £55,000 and £110,000 including the new kitchen and glazing, depending on size, specification and location.
- Can I stay in the house during a kitchen extension?
- Usually yes, but plan for several weeks with a temporary kitchen. Ask your builder when the existing kitchen has to come out.
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