Kitchen Extension Cost Guide UK
Planning a kitchen extension? Discover typical UK build costs, interior fit-out costs, professional fees and realistic budget examples to help you plan your project with confidence.
How Much Does a Kitchen Extension Cost?
A kitchen extension is one of the most popular ways to create additional living space and increase the value of your home. However, many homeowners focus only on the builder's quotation and underestimate the overall project budget.
A complete kitchen extension budget usually consists of three parts:
- Building the extension
- Interior fit-out
- Professional fees and contingency
This guide provides a realistic overview to help you budget with confidence before requesting quotations.
Looking for a personalised estimate? Try our free Kitchen Extension Cost Calculator.
Typical Kitchen Extension Build Costs
The figures below are for a typical single-storey kitchen extension and include the structural building works only. They exclude the kitchen, interior finishes and professional fees.
| Extension Size | Typical Build Cost |
|---|---|
| 20m² | £40,000–£60,000 |
| 30m² | £60,000–£85,000 |
| 45m² | £90,000–£130,000 |
Typical build costs usually include:
- Foundations and groundworks
- Brickwork and structural walls
- Roof structure and coverings
- Windows and external doors
- Structural steelwork
- Insulation
- First fix plumbing and electrics
- Plastering
Typical Additional Costs
These items are usually not included in the builder's extension price.
| Item | Typical | High Specification |
|---|---|---|
| Kitchen (units, worktops & appliances) | £15,000–£30,000 | £35,000–£70,000+ |
| Flooring | £40–£80/m² | £90–£180/m² |
| Electrical installation | £2,500–£5,000 | £5,000–£10,000 |
| Lighting | £1,500–£3,000 | £3,000–£8,000 |
| Decoration | £20–£40/m² | £45–£80/m² |
Professional Fees & Other Costs
| Item | Typical Cost |
|---|---|
| Architectural design | £2,000–£6,000 |
| Structural engineer | £500–£1,500 |
| Planning application (if required) | £500–£2,000 |
| Building Regulations | £800–£2,000 |
| Party Wall surveyor (if required) | £800–£3,000 |
| External works & landscaping | £1,000–£8,000 |
| Recommended contingency | 10–15% |
Typical Total Project Budgets
The examples below combine the extension build, interior fit-out, professional fees and contingency to give an indication of the overall investment.
| Extension Size | Typical Budget | High Specification |
|---|---|---|
| 20m² | £75,000–£100,000 | £105,000–£150,000+ |
| 30m² | £100,000–£135,000 | £140,000–£195,000+ |
| 45m² | £140,000–£190,000 | £190,000–£270,000+ |
These are planning budgets only. Actual costs depend on your location, design, structural complexity, specification and builder.
Final Thoughts
The cost of a kitchen extension is much more than the builder's quotation. By budgeting for the construction, kitchen, interior finishes and professional fees from the beginning, you'll have a much clearer picture of the total investment and be better prepared when comparing quotations.
Use our free Kitchen Extension Cost Calculator to estimate your project based on your extension size and specification.
Planning a similar project?
Get a realistic UK cost estimate before speaking to builders.