- What Does a Kitchen Extension Cost in the UK in 2026?
- What Drives the Cost of a Kitchen Extension?
- Hidden Costs to Budget For
- What Good Value Actually Looks Like
- How to Get a Realistic Figure for Your Project
- Kitchen Extension Costs: A Quick Summary
- Frequently Asked Questions
A kitchen extension remains one of the most popular home improvements in the UK, and it's easy to see why. It adds real, usable space, improves how your home feels day to day, and tends to hold its value well when you come to sell. But before you commit, you need a realistic picture of what it will actually cost — not a rough ballpark, but a figure that reflects your property, your brief, and where you live.
This guide breaks down kitchen extension costs across the UK in 2026, explains what drives the price up or down, and helps you go into the planning process with your eyes open.
What Does a Kitchen Extension Cost in the UK in 2026?
There's no single answer, because kitchen extensions vary enormously in size, specification, and complexity. That said, here are the broad ranges most homeowners are working with this year:
| Extension Type | Typical Cost Range |
|---|---|
| Small single-storey rear extension (up to 3m) | £30,000 to £55,000 |
| Mid-size single-storey rear extension (3m to 6m) | £55,000 to £90,000 |
| Large single-storey rear extension (6m+) | £90,000 to £140,000+ |
| Side return extension | £45,000 to £80,000 |
| Wrap-around (rear and side combined) | £80,000 to £150,000+ |
These figures cover structural work, glazing, roofing, flooring, and a fitted kitchen. They don't include furniture, appliances, or landscaping unless those are agreed as part of your project scope.
London projects typically sit at the upper end of these ranges. Labour costs are higher, access is often more restricted, and Victorian terraces bring their own structural considerations that can add time and cost.
What Drives the Cost of a Kitchen Extension?
A headline figure only tells you so much. Understanding what actually moves the price is far more useful when you're trying to plan a realistic budget.
Size and Footprint
The most obvious driver. A larger footprint means more materials, more groundwork, and more time on site. Going beyond 6 metres at the rear also triggers different planning rules in some boroughs, which can add both cost and lead time.
Structural Complexity
Opening up a rear wall requires a steel beam. If your home is a Victorian terrace with a party wall, you'll need a Party Wall Agreement with your neighbour before work can begin — that's a legal requirement, not an optional extra, and it takes time to arrange.
Shallow foundations, older drainage runs beneath the proposed footprint, or existing outbuildings that need demolishing all add to the structural cost. These are the kinds of things that only become visible once someone has properly assessed your property.
Glazing and Roof Design
Bifold or sliding doors, roof lanterns, and full-width glazed gables are popular choices for kitchen extensions. They flood the space with light and look striking, but they cost significantly more than a standard tiled roof with a single set of French doors. A well-specified glazed roof or large door system can add £8,000 to £20,000 to your budget.
Kitchen Fit-Out Specification
The kitchen itself is one of the biggest variables in the whole project. A mid-range fitted kitchen with stone worktops might cost £15,000 to £25,000. A bespoke, handmade kitchen from a specialist joiner can reach £40,000 to £60,000 or more. If you're commissioning the extension and the kitchen together, it's worth nailing down the kitchen specification early so your budget reflects the full picture from the start.
Location
London adds a premium across every trade. Projects in Chelsea, Notting Hill, or Ladbroke Grove will carry higher labour rates and skip hire costs than equivalent work elsewhere in the UK. Access restrictions, congestion charges, and permit requirements for skips on public roads all contribute.
Outside London, costs are generally 15 to 25 per cent lower for the same specification.
Design and Project Management
A design-and-build approach — where one team handles everything from initial drawings through to final handover — typically costs more than hiring a builder directly. But it removes the coordination burden from you, reduces the risk of errors between trades, and usually produces a more coherent result. For most homeowners, the time saved and the stress avoided more than justify the difference.
Hidden Costs to Budget For
These are the items that catch people out when they've only been quoted for the build itself.
Planning permission: A single-storey rear extension under 4 metres (3 metres for semi-detached or terraced homes) may qualify as permitted development, but many London projects require full planning permission. Budget £200 to £500 for the application fee, plus architect or designer fees to prepare drawings.
Structural engineer: Required for beam calculations and foundation design. Typically £500 to £1,500 depending on complexity.
Party Wall Agreement: If your extension is within 3 metres of a neighbour's property or involves work on a shared wall, a Party Wall Agreement is a legal requirement. A surveyor typically charges £700 to £1,500 per neighbour.
Building regulations approval: Separate from planning permission, and legally required for most extensions. Budget £500 to £1,000 for the application and inspections.
Contingency: Always hold back 10 to 15 per cent of your total budget for unexpected findings during groundwork or demolition. Older homes regularly reveal surprises once walls come down.
What Good Value Actually Looks Like
Low cost and good value are not the same thing. A contractor quoting 20 per cent below everyone else isn't necessarily saving you money — underbidding often leads to variation orders mid-project, delays while materials are sourced, or a finish that falls short of what you had in mind.
Good value means a detailed quote that covers the full scope of work, a realistic programme, and a team that communicates clearly throughout the build. Monthly budget tracking and on-site progress reports should be standard, not a premium add-on. If a contractor can't tell you where your money is going at any point during the project, that's worth taking seriously before you sign anything.
How to Get a Realistic Figure for Your Project
Generic price guides are useful for orientation, but they can't account for your specific property, your borough's planning requirements, or the specification you have in mind. The fastest way to understand what your kitchen extension might actually cost is to get an estimate based on your real brief.
At MVV, you can get an instant cost estimate online without booking a consultation first. It gives you a genuine ballpark figure based on your project type and scope, so you can plan your budget before committing to anything.
Every MVV project then includes detailed upfront budget planning, a single point of contact from design through to delivery, and monthly reports with budget tracking and on-site photography. No surprises, no chasing multiple contractors, and no gap between what was designed and what gets built.
Kitchen Extension Costs: A Quick Summary
- Small single-storey extensions start from around £30,000 to £55,000
- Mid-size and larger projects typically run from £55,000 to £140,000 or more
- London adds a meaningful premium across labour, access, and compliance
- Hidden costs — planning, structural engineering, Party Wall fees — can add £3,000 to £5,000 or more
- Always hold a contingency of 10 to 15 per cent
- The kitchen fit-out specification is one of the biggest single variables in your total cost
Frequently Asked Questions
How much does a kitchen extension cost in London in 2026?
Most London kitchen extensions fall between £55,000 and £140,000 depending on size and specification. Smaller single-storey rear extensions can come in below that range, while large wrap-around or highly specified projects often exceed it.
Does a kitchen extension add value to my home?
Generally, yes. A well-designed extension that improves the flow and usability of your home tends to increase its market value. The return depends on the quality of the work, the local property market, and how well the extension suits the rest of the house.
Do I need planning permission for a kitchen extension?
Not always. Some single-storey rear extensions qualify as permitted development, but the rules depend on your property type, the size of the extension, and your local authority. In London, many properties sit within Article 4 areas or conservation zones where permitted development rights are restricted. It's worth checking with your local planning authority or a design-and-build team before assuming you can proceed without permission.
How long does a kitchen extension take to build?
A typical single-storey kitchen extension takes 10 to 16 weeks on site once planning and building regulations approvals are in place. Larger or more complex projects can take longer. The design and planning phase before work starts often adds another 8 to 16 weeks.
What is a Party Wall Agreement and do I need one?
A Party Wall Agreement is a legal document required when your building work affects a shared wall or falls within 3 metres of a neighbouring property. It protects both you and your neighbour and is a legal requirement under the Party Wall etc. Act 1996. Your contractor or designer should flag this early in the process.
Is a design-and-build contractor worth the extra cost?
For most homeowners, yes. Coordinating an architect, structural engineer, main contractor, and specialist trades yourself takes significant time and carries real risk if communication breaks down between parties. A design-and-build team manages all of that under one roof, which typically produces a more consistent result and fewer costly errors.
What is a realistic contingency budget for a kitchen extension?
10 to 15 per cent of your total build cost is a sensible buffer. Older properties — particularly Victorian terraces — regularly reveal unexpected issues during groundwork or demolition. Having that reserve means you can deal with problems without derailing the project.
A kitchen extension is a significant investment. Getting the cost right from the start — with a real figure based on your specific project rather than an industry average — puts you in a much stronger position to plan, compare, and commit with confidence.
Get your free cost estimate in minutes at themvv.co.uk.