Kitchen Extension Cost: Full Price Breakdown
How much does a kitchen extension cost? Detailed breakdown covering build, kitchen units, professional fees, and regional variations.
A kitchen extension is the most popular type of home extension in the UK - and for good reason. It transforms the most-used room in the house, creates open-plan living space, and adds real value to your property. But it's also one of the most expensive home improvements, with total costs routinely catching homeowners off guard.
This guide breaks down every cost involved in a kitchen extension so you can budget accurately from the start.
The Three Cost Components
A kitchen extension has three distinct cost areas, and confusing them is the most common budgeting mistake:
1. The Build (Structure)
This is the shell: foundations, walls, roof, floor slab, windows, doors, drainage, and all structural work. This is what your builder quotes for.
2. The Kitchen (Fit-Out)
Units, worktops, appliances, splashbacks, lighting, flooring, and decoration. Often quoted separately by a kitchen supplier.
3. Professional Fees and Extras
Architect, structural engineer, Building Control, Party Wall surveyors, and all the hidden costs that sit outside the build and kitchen quotes.
Build Costs in Detail
The structural build is the largest single cost. Here's what to expect per square metre:
| Finish Level | Cost per m² | 20m² Extension | 30m² Extension |
|---|---|---|---|
| Budget | £1,500–£1,800 | £30,000–£36,000 | £45,000–£54,000 |
| Standard | £1,800–£2,500 | £36,000–£50,000 | £54,000–£75,000 |
| Premium | £2,500–£3,000 | £50,000–£60,000 | £75,000–£90,000 |
| Luxury | £3,000–£3,500+ | £60,000–£70,000 | £90,000–£105,000 |
These figures include:
- Foundations and ground slab
- External walls (block and brick or render)
- Roof structure (flat or pitched)
- Internal plastering and screeding
- Windows and external doors
- Basic electrics and plumbing first fix
- Drainage connection
They don't include: kitchen units, appliances, floor finishes, decoration, or professional fees.
What Drives Build Cost Up?
Several factors push costs above the baseline:
- Structural steelwork - removing a load-bearing wall to create open plan adds £1,500–£4,000 for steel and installation
- Underfloor heating - £50–£80 per m² for a wet system, £30–£50 for electric
- Bifold or sliding doors - a 3-metre set of aluminium bifolds costs £3,000–£6,000 vs £1,500–£2,500 for standard French doors
- Vaulted or lantern roof - a roof lantern adds £2,000–£5,000 but transforms the space with overhead light
- Complex foundations - trees, clay soil, or proximity to drains can add £2,000–£8,000
- Pitched roof vs flat - a pitched roof adds £1,500–£3,000 but looks more proportionate on larger extensions
Kitchen Costs in Detail
The kitchen itself is where budgets vary most wildly:
Budget Kitchen: £3,000–£6,000
- Flat-pack units from B&Q, IKEA, or Wickes
- Laminate worktops
- Basic integrated appliances
- DIY or semi-professional fitting
Mid-Range Kitchen: £6,000–£15,000
- Rigid units from Howdens, Wren, or Magnet
- Quartz or solid timber worktops
- Quality integrated appliances (Bosch, Neff, AEG)
- Professional installation
Premium Kitchen: £15,000–£30,000
- Bespoke or premium brand units (Schuller, Nobilia, Harvey Jones)
- Granite, Dekton, or Corian worktops
- High-end appliances (Miele, Siemens iQ700, Sub-Zero)
- Designer lighting and hardware
Luxury Kitchen: £30,000–£50,000+
- Handmade bespoke cabinetry
- Natural stone or bespoke material worktops
- Professional-grade appliances (Wolf, Gaggenau)
- Integrated butler's pantry or utility room
Tip: Order your kitchen early in the build process - lead times for mid-range and premium kitchens are typically 4–8 weeks. Budget kitchens from B&Q or IKEA can be picked up in days.
Professional Fees and Extras
These costs sit outside both the builder's and kitchen supplier's quotes:
| Item | Typical Cost |
|---|---|
| Architect / architectural technologist | £1,500–£5,000 |
| Structural engineer | £500–£1,500 |
| Planning application (if needed) | £258 |
| Building Control | £500–£1,200 |
| Party Wall surveyor(s) | £800–£3,000 |
| Temporary kitchen setup | £200–£500 |
| Skip hire (2–3 skips) | £500–£1,000 |
| Scaffolding | £500–£1,200 |
| Subtotal | £4,500–£13,000 |
For a detailed breakdown of these additional expenses, see our guide to hidden extension costs.
Total Cost: Putting It All Together
Here's the full picture for a typical 20m² single-storey kitchen extension:
| Component | Budget | Standard | Premium |
|---|---|---|---|
| Build (20m²) | £30,000 | £40,000 | £55,000 |
| Kitchen + appliances | £5,000 | £12,000 | £25,000 |
| Professional fees & extras | £5,000 | £7,000 | £10,000 |
| Landscaping / making good | £2,000 | £4,000 | £6,000 |
| Contingency (10%) | £4,200 | £6,300 | £9,600 |
| Total | £46,200 | £69,300 | £105,600 |
These are national averages. Apply regional multipliers:
| Region | Adjustment |
|---|---|
| Inner London | +30–45% |
| Outer London / South East | +15–25% |
| South West / East | +5–10% |
| Midlands | Baseline |
| North West / Yorkshire | −5–10% |
| North East / Wales | −10–20% |
For a personalised estimate based on your exact location and specification, use our free extension quote calculator. You can also browse kitchen extension costs by city to see how prices compare across the UK.
Saving Money Without Cutting Corners
Do
- Get 3+ builder quotes and compare what's included line by line
- Separate the kitchen purchase from the build - you'll often get better value buying direct from a kitchen supplier than through your builder
- Choose a flat roof over pitched for smaller extensions (saves £1,500–£3,000)
- Use standard-size windows and doors - custom sizes are significantly more expensive
- Bundle the kitchen extension with other planned work (rewiring, new boiler, damp proofing) to share setup costs
Don't
- Choose the cheapest builder - get references and check previous work through the Federation of Master Builders
- Skip the structural engineer - their fee is tiny compared to the cost of getting steelwork wrong
- Forget the Party Wall Act if you're on a semi or terrace
- Underestimate the timeline - plan for 4–6 months from design to move-in
Next Steps
- Set your total budget - use the tables above as a starting point
- Get a detailed estimate - our free quote tool gives an itemised cost breakdown for your area
- Appoint an architect or technologist - find a chartered professional through RIBA or CIAT
- Start Party Wall notices early - build 2–3 months into your timeline
- Read about financing options if you need to borrow
Frequently Asked Questions
Ready to Get a Quote?
Use our free calculator to get a personalised, itemised estimate for your project - tailored to your location and specification.