Table of Contents
- What Does a Kitchen Extension Cost in London in 2026?
- Types of Kitchen Extension
- What Affects the Cost?
- Planning Permission vs Permitted Development
- Design Considerations for a Kitchen Extension
- How Long Does a Kitchen Extension Take?
- Choosing the Right Contractor in London
- FAQs
A kitchen extension is one of the most effective investments you can make in a London home. Done well, it creates an open, functional space that genuinely changes how you live day to day. Done badly, it costs more than it should and runs months over schedule.
This guide covers what you actually need to know before starting: realistic 2026 costs, the most common extension types, planning rules, and what separates a good contractor from a costly one.
What Does a Kitchen Extension Cost in London in 2026?
Costs vary considerably depending on size, specification, and where in London you are. These are realistic ballpark figures for 2026:
| Extension Type | Approximate Cost Range |
|---|---|
| Small single-storey rear (up to 4m) | £40,000 – £65,000 |
| Medium single-storey rear (4–6m) | £65,000 – £95,000 |
| Side return extension | £55,000 – £85,000 |
| Wraparound extension | £90,000 – £140,000+ |
| Double-storey extension | £100,000 – £180,000+ |
These figures cover structural work, glazing, kitchen fit-out, and mid-range finishes. Bespoke joinery, high-end materials, or an unusually complex structural situation will push the number higher.
London pricing typically runs 20–30% above the national average. Labour costs across SW, W, and SE postcodes are among the highest in the country, and working in dense urban areas adds both time and logistics costs.
The quickest way to get a project-specific figure is to use MVV's instant cost estimator at themvv.co.uk. You get a ballpark number without booking a consultation first, so you can sense-check your budget before committing any time to the process.
Types of Kitchen Extension
Single-Storey Rear Extension
The most common approach in London. You extend the back of the house into the garden — typically 3–6 metres — and open up the ground floor into a larger kitchen-dining or kitchen-living space.
Rear extensions suit Victorian and Edwardian terraces particularly well, which make up a large share of housing stock across SW and SE London. The existing rear wall comes down, a steel frame carries the load, and a flat or pitched roof with roof lights brings natural light into the new space.
Side Return Extension
The side return is the narrow strip of land running alongside the kitchen in a typical London terrace — often just 1–1.5 metres wide and used for little more than bins and bikes.
Infilling it adds useful floor area, but more importantly it changes the shape of the kitchen. A narrow galley becomes a wider, more workable room. Combined with a rear extension, a side return creates a wraparound layout.
Wraparound Extension
A wraparound combines a rear extension with a side return infill to produce an L-shaped addition. It is the most popular choice for homeowners who want a genuinely spacious kitchen-diner — room for an island, a dining table, and a separate seating area without everything feeling cramped.
Wraparounds are structurally more involved and need careful design to avoid a dark, enclosed feel. Roof lights and full-width glazing at the rear are the standard solutions.
Double-Storey Extension
Adding a second storey above the kitchen extension — typically a bedroom or bathroom — improves the cost-per-square-metre significantly compared to a single-storey build. If your budget and planning situation allow it, a double-storey rear extension is often the most efficient way to add space.
These projects almost always require full planning permission and need careful design to protect light to neighbouring properties.
What Affects the Cost?
Several factors can move the final figure meaningfully in either direction.
Size and footprint. Cost scales with floor area, but not in a straight line. A 6m extension costs more than twice a 3m extension once you account for structural complexity, longer steel spans, and larger glazing requirements.
Specification. A flat roof with roof lights costs less than a lantern roof with structural glazing. A standard kitchen fits out at a very different price point to bespoke cabinetry. Specification choices alone can shift the total by 20–40%.
Structural complexity. Older London properties can have shallow foundations, party wall complications, or load-bearing walls in unexpected positions. A structural survey early in the process is the best way to avoid surprises mid-build.
Party wall agreements. If your extension sits on or near a shared boundary, you will need a party wall agreement with your neighbour. This typically adds £1,000–£2,000 per neighbour and a statutory two-month notice period.
Glazing. Large glazed doors and roof lights are one of the biggest single cost variables in any kitchen extension. Aluminium bifold or sliding doors across the rear can range from £3,000 to £15,000 or more depending on size and specification.
Finishes and fit-out. Flooring, kitchen units, worktops, and appliances are consistently underestimated. Budget at least £15,000–£25,000 for a mid-range kitchen fit-out in a London extension project.
Planning Permission vs Permitted Development
Many kitchen extensions in London can be built under permitted development rights, meaning no formal planning application is required. The rules are specific, though, and London's density means they hit their limits more often than elsewhere.
Under permitted development, a single-storey rear extension can extend:
- Up to 4 metres for a detached house
- Up to 3 metres for a semi-detached or terraced house
These limits can increase to 8 metres (detached) and 6 metres (other) under the neighbour consultation scheme, provided no objections are raised.
Permitted development does not apply if:
- Your property is in a conservation area
- Your property is listed
- Previous extensions have already used the permitted development allowance
- The extension would cover more than 50% of the original garden area
A significant proportion of London's Victorian and Edwardian terraces sit in or near conservation areas — particularly across SW3, SW6, W10, and SE3. If yours does, you will need full planning permission, which adds 8–12 weeks to the programme and requires a more detailed design submission.
Always check with your local planning authority before assuming permitted development applies. A good design and build contractor will confirm this for you as part of the initial design process.
Design Considerations for a Kitchen Extension
Getting the design right matters as much as the build quality. These are the decisions that shape how the space actually feels to live in.
Natural light. A rear extension can easily feel dark without careful thought about light. Roof lights above the kitchen zone, full-width glazing at the rear, and a considered ceiling height all make a real difference. In a wraparound, the junction between old and new is where light is most easily lost — a structural glass roof or a large lantern solves this well.
Connection to the garden. Most homeowners want the extension to open directly onto the garden. Sliding or folding doors across the full rear elevation achieve this, but the threshold detail matters. A flush floor level between inside and outside, with a consistent material at the junction, makes the space feel considered rather than tacked on.
Ceiling height. Standard ceiling heights can feel low in a large open-plan space. Even a modest step up to 2.7m or 3m in the extension zone — where the existing ground floor sits at 2.4m — changes the feel of the room considerably.
Kitchen layout. The extension is an opportunity to rethink the layout entirely. An island works well in a wider space, adding worktop area, storage, and a natural social focal point. Think about the working triangle between hob, sink, and fridge before fixing the layout.
Heating and ventilation. Underfloor heating is standard in new extensions and works well under stone or large-format tile. Check that the boiler has sufficient capacity before committing to the layout. If a ceiling-mounted extractor is part of the brief, ventilation above the hob needs to be planned into the structural design from the outset.
How Long Does a Kitchen Extension Take?
A realistic timeline for a London kitchen extension in 2026:
| Stage | Typical Duration |
|---|---|
| Design and planning (permitted development) | 6–10 weeks |
| Design and planning (full planning permission) | 14–20 weeks |
| Structural calculations and building regulations | 4–6 weeks (can run concurrently) |
| Party wall process (if required) | 8–12 weeks (can run concurrently) |
| Build programme | 10–18 weeks depending on size |
From first appointment to completion: typically 6–9 months for a permitted development project, and 9–14 months where full planning permission is required.
These timelines assume a contractor who manages design, planning, and build without gaps between stages. When design and build are handled by separate firms, handoff delays are one of the most common reasons programmes run over.
Choosing the Right Contractor in London
Budget overruns and unreliable contractors are the two things London homeowners worry about most when starting a construction project. Both are largely preventable — with the right contractor and the right contract structure.
Here is what to look for:
A single team from design to build. When the same firm handles design, planning, and construction, there are no gaps where responsibility falls between parties. You have one point of contact, and the team that designs the extension is the team that builds it. This matters when decisions need to be made quickly on site.
Ongoing budget transparency, not just an upfront quote. An initial estimate is useful, but it is not enough. A contractor who provides monthly budget tracking throughout the build gives you the information you need to make decisions before costs escalate — not after.
Monthly progress reports with photography. This should be a named deliverable, not a vague promise of regular updates. You should be able to see what has happened on site, what has been spent, and what is coming next, every single month.
Relevant local experience. A contractor who has delivered projects in your postcode understands the local planning environment, the structural quirks of the housing stock, and the supply chain in your area. Completed projects in Fulham, Wimbledon, Chelsea, and Notting Hill are evidence of that.
Verifiable social proof. Video testimonials and named client reviews carry more weight than anonymous star ratings. Repeat work and referrals from structural engineers and architects are both strong indicators of consistent delivery.
MVV works across London, with completed projects in SW6, SW19, SW3, SE3, and W10. Every project runs from concept to completion under one team, with monthly reports covering budget tracking and on-site photography. You can get an instant cost estimate for your kitchen extension — no consultation required — at themvv.co.uk.
FAQs
How much does a kitchen extension cost in London in 2026?
A small single-storey rear extension starts at around £40,000–£65,000. A mid-sized side return or wraparound typically falls between £65,000 and £140,000. Double-storey extensions start at around £100,000. The final figure depends on size, specification, structural complexity, and finish level. An instant online estimator gives you a project-specific ballpark before you speak to anyone.
Do I need planning permission for a kitchen extension in London?
Many kitchen extensions fall under permitted development rights and do not require a planning application. However, properties in conservation areas, listed buildings, and those that have already used their permitted development allowance will need full planning permission. A significant number of London terraces sit in or near conservation areas, so it is worth checking before assuming.
How long does a kitchen extension take from start to finish?
A permitted development project typically takes 6–9 months from first appointment to completion. Projects requiring full planning permission take 9–14 months. The build programme itself usually runs 10–18 weeks depending on size and complexity.
What is a side return extension?
A side return extension fills in the narrow strip of land running alongside the kitchen in a typical London terrace. Infilling it adds floor area and widens the kitchen from a galley into a more usable space. Combined with a rear extension, it creates a wraparound layout.
What is the difference between permitted development and full planning permission?
Permitted development is a right that allows certain extensions without a formal planning application, subject to size and location limits. Full planning permission requires a formal application, a design submission, and a statutory determination period of 8–13 weeks. Properties in conservation areas, or those exceeding permitted development size limits, need full planning permission.
How do I avoid budget overruns on a kitchen extension?
Work with a contractor who provides ongoing budget tracking throughout the build, not just an upfront quote. Monthly reports showing actual spend against budget give you early visibility of any variance. Fixing the specification before work starts and agreeing a detailed contract also reduces the risk of scope creep.
What should I look for when choosing a kitchen extension contractor in London?
A single team that handles design and build without handoffs, transparent cost management with monthly budget reporting, verifiable completed projects in your area, and clear social proof from named clients. A contractor who can give you a cost estimate before you commit to a consultation is also a strong signal of transparency.
Getting a kitchen extension right in London comes down to three things: a well-considered design, a realistic budget, and a contractor who stays accountable from start to finish. The planning and cost questions are answerable early if you have the right information to hand. Get a project estimate at themvv.co.uk and you will know where you stand before you speak to anyone.