A 24m² (6m by 4m) single storey kitchen extension at mid spec, with bifold doors, a roof lantern and a new kitchen, costs £71,500 to £82,500 including VAT and professional fees at West Midlands rates. That works out at about £3,180 per m². In inner London the same job is £93,000 to £115,500; in the North East it is £66,500 to £79,500. Below is what sits inside that number and how size, spec and glazing move it.
- Compact 4m by 4m, standard spec: £56,000 to £64,500
- 6m by 4m, standard spec: £67,000 to £77,000
- 6m by 4m, mid spec: £71,500 to £82,500
- 6m by 4m, high spec: £86,000 to £99,000
- Side return, 6m by 2.5m, mid spec: £62,500 to £71,500
Every figure comes from Quoteio’s free calculator. Enter your postcode there, or see prices by region.
Why is a kitchen extension more expensive than a plain extension?
A kitchen extension is two projects at once. First there is the structure: foundations, walls, roof, drainage, electrics and plumbing. Then there is everything that turns it into a kitchen: units and worktops, a big glazed opening onto the garden and usually a rooflight or lantern to bring daylight into the middle of a deep room. People budget carefully for the first and underestimate the second.
On our typical 6m by 4m mid spec job, the empty shell with fees and VAT comes to £61,000 to £70,000. Adding the kitchen allowance, bifold doors and a lantern takes it to £71,500 to £82,500. A kitchen also needs more electrics and plumbing than a lounge or playroom, which is why the engine prices services from floor area rather than as a flat fee.
Where does the money go?
Here is how the engine splits the typical mid spec kitchen extension. Everything is shown ex VAT, with VAT added at the bottom.
| Part of the job | Cost |
|---|---|
| Structure (foundations to roof, services, labour) | £49,826 |
| Kitchen units and fitting allowance | £5,600 |
| Bifold doors and roof lantern | £4,000 |
| Drawings, engineer, Building Regs, planning fee | £4,178 |
| VAT at 20% | £12,721 |
| Total | £76,325 |
The calculator shows the total as a range (£71,500 to £82,500) because no two sites are the same. Read how we set the range.
The structure is by far the biggest slice. That is worth remembering when you are tempted to save money on the kitchen: a cheaper worktop changes the total far less than taking a metre off the depth of the room.
How much does size change the price?
Footings, scaffold, drainage and the planning fee cost much the same whether the room is small or large, so the price per m² falls as the room gets bigger. These are all mid spec with a kitchen, bifolds and a lantern, apart from the first row.
| Size | Typical price inc VAT and fees |
|---|---|
| 4m by 4m (16m²), standard spec about £3,730 per m² | £56,000 to £64,500 |
| 6m by 2.5m side return (15m²) about £4,420 per m² | £62,500 to £71,500 |
| 6m by 4m (24m²) about £3,180 per m² | £71,500 to £82,500 |
| 8m by 4.5m (36m²) about £2,560 per m² | £86,500 to £99,500 |
A side return infill is popular on Victorian and Edwardian terraces, where the narrow alley beside the back addition is wasted space. It is a smaller room, but it usually involves a party wall with the neighbour, which the engine allows for with a party wall surveyor fee.
Standard, mid or high spec: what changes?
Spec in the calculator is not just the kitchen. It changes the wall build-up, the roof, the size of the glazing and the level of the professional fees. For the same 6m by 4m room with a kitchen, bifolds and a lantern:
| Spec level | Typical price inc VAT and fees |
|---|---|
| Standard Blockwork walls, flat GRP roof, 3-pane bifold, basic kitchen allowance | £67,000 to £77,000 |
| Mid Cavity walls, larger glazing, mid-range kitchen allowance | £71,500 to £82,500 |
| High Face brick, pitched slate roof, 5-pane bifold, premium kitchen allowance | £86,000 to £99,000 |
Bifolds and a lantern, or French doors?
Big glazing is what makes a kitchen extension feel special, and it is one of the few line items you can change without touching the structure. On a 6m by 4m standard spec job, swapping the bifolds and lantern for a single set of French doors saves about £2,040, bringing the price to £65,000 to £74,500. You lose daylight in the back of the room, so if you go this way, consider one or two rooflights instead, which you can add in the calculator.
How much does a kitchen extension cost in my region?
Labour and materials cost more in London and the South East and less in the North East and Northern Ireland. Kitchens and glazing are mostly supply cost, so only part of the regional difference applies to them. Here is the typical 6m by 4m mid spec kitchen extension next to the plain 5m by 4m standard spec shell in every region.
| Region | Kitchen extension 24m², mid | Plain extension 20m², standard |
|---|---|---|
| Inner London | £93,000 to £115,500 | £71,000 to £88,500 |
| Outer London | £84,000 to £104,500 | £64,000 to £79,500 |
| South East | £78,500 to £94,000 | £59,500 to £71,000 |
| East of England | £75,500 to £90,000 | £57,000 to £68,000 |
| South West | £73,500 to £88,000 | £55,500 to £66,000 |
| East Midlands | £69,500 to £83,000 | £52,000 to £62,500 |
| West Midlands | £71,500 to £82,500 | £54,000 to £62,000 |
| North West | £69,500 to £83,000 | £52,000 to £62,500 |
| Yorkshire and the Humber | £67,500 to £81,000 | £50,500 to £60,500 |
| North East | £66,500 to £79,500 | £49,500 to £59,500 |
| Wales | £67,500 to £81,000 | £50,500 to £60,500 |
| Scotland | £70,000 to £83,500 | £52,500 to £63,000 |
| Northern Ireland | £63,500 to £76,000 | £47,500 to £56,500 |
If you live in or around Birmingham, Dudley or Wolverhampton, our West Midlands prices come straight from completed local jobs. For the capital, see London extension costs, where site access and party walls widen the range.
What is not included in these prices?
- Appliances. Ovens, hobs, fridges and dishwashers are not in the kitchen allowance.
- A designer kitchen. The allowance covers standard units. If your kitchen supplier has quoted, use their figure.
- Knocking through. Opening up the back wall of the house needs steel beams and making good. Ask your builder to price it separately.
- Moving the boiler or soil stack. Common in kitchen moves, and only priced once a builder has seen it.
- Ground conditions. Clay, tree roots or a public sewer under the footprint can change the foundations.
- Flooring, decorating and landscaping after the build.
Do you need planning permission for a kitchen extension?
Many single storey rear extensions in England can be built under permitted development, which usually means no full planning application, provided the extension stays within the depth and height limits and the house still has its permitted development rights. Side extensions, homes in conservation areas, listed buildings and flats are usually treated differently. Your council can confirm, and a lawful development certificate gives you written proof. Our prices include the householder planning fee to be safe. Building Regulations approval is needed in every case.
How do I get an accurate price for my kitchen extension?
- Measure the outside footprint you want and run it through the calculator with your postcode, rooms and glazing.
- Use that range to set your budget before you speak to an architect, so the design matches the money.
- Get at least three written quotes from builders working from the same drawings.
- Keep a contingency for the things nobody can see until the ground is open.
Planning a bigger project? Our full UK extension cost guide compares every type of extension, and the single storey extension guide breaks the structure down trade by trade.
Common questions
How much does a kitchen extension cost in the UK?
A 6m by 4m single storey kitchen extension at mid spec, with bifold doors, a roof lantern and a new kitchen, costs £71,500 to £82,500 at West Midlands rates including VAT and professional fees. The same job is £66,500 to £79,500 in the North East and £93,000 to £115,500 in inner London.
Does a kitchen extension need planning permission?
Many single storey rear kitchen extensions fall under permitted development, so they usually do not need a full planning application, as long as they stay within the size and height limits and the house has not had its permitted development rights removed. Side extensions, larger rear extensions, flats, listed buildings and homes in conservation areas often do. Check with your council or apply for a lawful development certificate for certainty. Building Regulations approval is needed either way.
Is the kitchen itself included in the price?
Our figures include an allowance for supplying and fitting kitchen units at each spec level (£6,720 inc VAT on the mid spec example). Appliances and designer kitchens are not included. If you have a quote from a kitchen supplier, use that figure instead of the allowance.
What is the cheapest way to get a bigger kitchen?
Keep the footprint modest and the glazing simple. On a 6m by 4m standard spec extension, French doors instead of bifolds and a roof lantern bring the price to £65,000 to £74,500. Knocking through to an existing dining room without extending at all is cheaper again, though it still needs a structural engineer and Building Regulations sign-off.