How Much Does a Kitchen Extension Cost in the UK?
Planning a kitchen extension is exciting, but the cost can bring you back to earth with a bump. The figures can be higher than expected, and it’s not always obvious what drives the budget up. Prices are often higher than expected, and it’s not always clear what drives them. In the UK, guide costs vary widely depending on size, spec and location.
This guide isn’t about Beams Renovation’s own pricing. It’s here to give you a clear sense of average UK figures, based on industry data and completed projects. With the right expectations, you’ll make better design calls - and avoid nasty surprises.
Average Kitchen Extension Costs
In the UK, a kitchen extension typically costs £1,750 - £2,350 per m² of new internal space. These are national guide prices - not Beams’ own fees.
To put that into context:
- A modest 20m² rear extension could range from £35,000 to £47,000.
- A 30m² single-storey kitchen extension often lands between £52,500 and £70,500.
In higher-cost areas (like London and the South East), premiums on labour and materials can push costs higher. Rural builds may come in at the lower end.
What Influences the Cost?
Size matters, of course - but it’s far from the only factor. The spec and structural demands make just as much difference.
- Size: Bigger builds mean more materials, more labour, and often, more structure.
- Specification: A kitchen extension with standard uPVC windows will cost less than one with full-width aluminium bifolds or a glass roof.
- Construction method: Traditional masonry is often the most cost-effective. SIPs or timber frame may carry a premium.
- Location: A project in central London will almost always cost more than a similar build in the Midlands due to labour rates.
A Realistic Cost Breakdown
Here’s a rough guide to how a typical 30 m² rear extension breaks down::
- Structure (foundations, walls, roof): ~£20,000
- Plumbing and heating: ~£3,500
- Electrics and lighting: ~£3,500
- Flooring: ~£1,500
- Kitchen units and worktops: ~£15,000
- Bifold doors: ~£3,500
- Decorating: ~£2,000
- Making good/landscaping: ~£2,000
This brings the total to around £51,000–£55,000 plus VAT. Adding mid-range kitchen appliances, worktops, and finishes could take the final figure to £65,000 or more. Again, these are averages - real projects will vary.
Don’t Forget the Hidden Costs
Beyond the obvious build costs, there are additional fees that often catch homeowners off guard. Planning permission applications (currently £258 in England), Building Regulation approval, and structural engineer drawings are all necessary.
If your project involves a Party Wall Agreement, expect around £1,500 in fees (higher in London). Insurance, waste disposal, scaffolding, and temporary site facilities can add thousands more. These aren’t always visible in initial quotes, so they’re worth flagging early.
How Design Choices Affect Costs
The kitchen itself is often the most expensive part of the project. A basic DIY kitchen might come in under £5,000, but most homeowners spend closer to £10,000–£20,000 on cabinetry and appliances, with premium designs reaching much higher.
Worktops range from affordable laminates at £30–40/m² to high-end quartz or Corian at £400–£500/m². Lighting design, taps with instant boiling water, and integrated smart appliances also add to the final total.
This is where many families use the extension as a chance to invest in a full kitchen remodel or redesign, rather than just creating additional floor space.
Compact Extensions
Not every build needs to be big. Side returns and small rear additions - popular in terraced homes - often cost £30,000–£45,000. They may add fewer m², but they can hugely improve layout, flow and light.
If you’re working with tighter dimensions, it’s worth looking at clever ways to optimise the space. Take a look at our guide to small kitchen extension ideas.
Planning Your Budget
Every extension involves trade-offs between size, specification, and budget. Phasing work is sometimes the most sensible approach if the whole house needs attention.
Before committing to an architect’s drawings, it’s worth modelling costs using a renovation cost calculator. This can highlight whether your vision is realistic before you start spending on fees.
Beams Renovation’s Take
A kitchen extension is one of the most rewarding changes you can make — but costs can snowball without a plan. The happiest homeowners are the ones who:
- Prioritise what matters most to their lifestyle
- Balance ambition with flexibility
- Keep a contingency for the unexpected
If you’re thinking about extending, a thoughtful kitchen redesign can sometimes deliver just as much value as square metres of new space. For those with smaller homes, small kitchen extension ideas can spark inspiration. And before any plans are signed off, we always recommend running numbers through a renovation cost calculator to avoid shocks down the line.
At Beams Renovation, we design and build kitchen extensions that blend beauty, practicality and long-term value.
Frequently Asked Questions
How much does a kitchen extension add to the value of a home?
A well-designed kitchen extension often adds between 10–15% to the property’s value, depending on location and design quality. It’s one of the most popular improvements buyers look for in the UK.
Do I always need planning permission for a kitchen extension?
Not always. Many kitchen extensions fall under permitted development rights, provided they meet certain size and design criteria. However, it’s advisable to confirm with your local authority and secure a certificate of lawful development.
Can I save money by managing parts of the project myself?
Yes, some homeowners save 15–30% by project managing or taking on elements of the labour themselves. But savings need to be weighed against the risk of delays, compliance issues, and additional stress.
What’s the cheapest way to build a kitchen extension?
Using standard materials (such as brick and block masonry), choosing simpler glazing, and keeping plumbing where it is to keep costs down.