Cost calculator
Kitchen extension cost calculator
A kitchen extension is two projects sold as one: the shell, and the kitchen inside it. Most quotes price the shell accurately and carry a provisional sum for everything you actually care about.
New floor area created by the extension.
Broad trade availability keeps day rates near the national average.
Estimated range, ex VAT
£54,000 – £92,500
- Labour (typical)
- £38,000
- Materials (typical)
- £35,000
Guidance only. A real quotation depends on site conditions, specification and access — which is exactly what an independent review of your own quote will tell you.
What affects the cost
Structural opening to the house
Removing the rear wall needs a substantial beam, often the largest single structural item in the job.
Glazing
Bifolds, sliders, lanterns and rooflights typically account for 15–25% of a kitchen extension budget.
Kitchen specification
The kitchen itself can range from £8,000 to £45,000 in the same physical space.
Side return constraints
London side returns involve party walls, restricted access and hand-dug foundations.
Underfloor heating and finishes
Screed, UFH, large-format tiling and levelling into the existing house.
Regional pricing differences
Materials cost roughly the same everywhere in the UK; labour does not. Use the region selector above to apply a local index — London and the South East typically run 15–30% above the national average, while the North East, Northern Ireland and Yorkshire sit below it.
Labour vs materials
Roughly 52% of this type of work is labour and 48% materials. Shell labour and materials split roughly evenly; the kitchen fit-out inside pushes materials higher.
Common hidden costs
- Provisional sums for kitchen, flooring and glazing that get replaced by real, higher numbers.
- Party wall awards and structural engineer's fees.
- Rerouting the boiler flue, soil pipe and external drainage.
- Making good and redecorating the rooms that connect to the new space.
How to save money
- Fix the kitchen supplier and specification before signing the build contract so provisional sums become fixed.
- Choose rooflights over a full lantern where the roof structure allows.
- Keep the sink and drainage on the existing wall.
- Get all quotes priced against the same drawings, glazing schedule and kitchen budget.
Frequently asked questions
How much is a kitchen extension?
£55,000–£95,000 ex VAT for a 25m² rear extension including a mid-range kitchen in 2026, more in London.
Is a side return worth it?
In Victorian terraces it usually transforms the ground floor for a smaller footprint than a full rear extension.
How long does a kitchen extension take?
Fourteen to twenty weeks from breaking ground to a usable kitchen.
Can I stay in the house?
Usually yes, with a temporary kitchen for six to ten weeks. Factor in the cost and disruption.
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