A kitchen extension in London can totally change the way you live and use your space, but you’ve got to plan your budget carefully. Construction costs here are higher than most of the UK—blame it on steep labour rates, material transport, planning headaches, and the tricky logistics of working in crowded city streets.
Most London homeowners should budget between £25,000 and £190,000 for a kitchen extension, depending on size, finishes, and structural complexity.
Knowing what actually drives these costs can help you make smarter choices (and avoid ugly surprises). The price swings a lot based on your extension’s square meterage, the materials you pick, how much structural work is needed, and whether you need planning permission or party wall agreements.
Labour and professional fees stack up fast in the capital, where skilled trades and architects don’t come cheap.
This guide breaks down the real numbers behind kitchen extensions in London for 2026. You’ll gain insight into what to expect at various budget levels, what factors drive costs up or down, and how to plan a project that delivers value without depleting your savings.
Key Takeaways
- Kitchen extension costs in London typically range from £25,000 for a small, basic build to £190,000 for a large, open-plan space with premium finishes.
- Planning permission, building regs, and party wall agreements add time and cost, but you can’t skip them in most London boroughs.
- Smart material choices, building in phases, and comparing several contractor quotes can help you save money without sacrificing quality.
Average Kitchen Extension Costs in London
Kitchen extension costs in London are noticeably higher than the rest of the UK. Most projects land somewhere between £40,000 and £150,000, depending on size and complexity.
Labour, material transport, and planning requirements in London add 20-40% to construction costs compared to other regions.
Cost Ranges by Extension Type
Single-storey extensions usually cost between £30,000 and £80,000 in London. A rear kitchen extension of 20 square metres will run from £30,000 to £50,000 for a basic build.
A more substantial 30-square-metre project ranges from £50,000 to £80,000. Side return extensions, which are popular in Victorian terraces, generally cost £50,000 to £75,000.
These narrow extensions use that alley space beside your house, adding 10-15 square metres to your kitchen. Wrap-around extensions combine rear and side return builds, creating substantial open-plan spaces.
Budget £70,000 to £100,000 for standard finishes, but high-end projects can hit £120,000 or more. Multi-storey extensions are the biggest investment at £80,000 to £150,000.
These add both kitchen space and rooms above, but need scaffolding and more complex structural work, which bumps up the cost.
Kitchen Extension Cost per Square Metre
In London, construction costs for kitchen extensions average £1,500 to £3,000 per square metre. Basic builds with standard finishes sit at the lower end, around £1,500 to £2,000 per square metre.
Mid-range projects with better materials and fixtures usually cost £2,000 to £2,500 per square metre. High-spec builds with premium materials, underfloor heating, and bespoke joinery can hit £2,500 to £3,000 per square metre or more.
Location really matters. Inner London boroughs like Westminster or Camden see costs 15-25% higher than places like Bromley or Enfield, thanks to trickier access, parking permits, and steeper labour rates.
Recent Project Examples in London
In Clapham, a 25-square-metre rear kitchen extension in 2025 cost £62,000. That included bi-fold doors, a flat roof with skylights, and mid-range kitchen units.
The project took about 10 weeks. Over in Islington, a side return extension added 18 square metres for £58,000 in early 2025.
The owner went for engineered oak flooring, quartz worktops, and handleless cabinets. Structural work and planning fees tacked on another £8,000.
A wrap-around extension in Ealing finished in autumn 2025 cost £95,000 for 40 square metres. This one had underfloor heating, a pitched glass roof, and high-end appliances.
Professional fees and party wall agreements added £12,000 on top.
Key Factors Affecting Kitchen Extension Prices
A bunch of elements decide how much you’ll spend on a London kitchen extension. Your location, build size, and choice of materials all play a big part in the final bill.
Location and Property Type
London boroughs charge different rates for labour and materials. Central and inner London areas usually cost 15-25% more than outer boroughs, since builders are in higher demand and access is tougher.
A terraced house in Westminster, for example, will have pricier logistics than a detached property in Bromley.
Your property type affects structural requirements too. Victorian terraces often need party-wall agreements and specialist brickwork matching, which can add £2,000-£5,000.
Semi-detached and detached homes usually offer easier access for materials and equipment, which cuts down on labour time and costs.
Planning restrictions vary by borough. Some areas have Article 4 directions that remove permitted development rights, so you’ll need to submit full planning applications at £206-£462.
Conservation areas have stricter rules on materials and design. You might need premium brickwork or specific window styles, which cost more than standard options.
Extension Size and Layout
Size is a huge driver of cost. A compact 9 m² extension typically costs £40,000-£60,000, while a 20 m² open-plan space runs £110,000-£190,000.
You’ll pay roughly £1,500-£3,000 per square metre depending on the spec. Complex layouts cost more.
Removing load-bearing walls means steel beams at £1,000-£3,000 per beam, plus structural engineer fees of £500-£1,500. Open-plan designs need extra electrical outlets, underfloor heating zones, and better soundproofing compared to simple rectangular extensions.
Ceiling height matters too. Standard 2.4-metre ceilings cost less than 3-metre heights, which need more brickwork, bigger windows, and extra heating.
Materials and Finishes
Your material choices shape both upfront costs and long-term value. Standard UPVC windows cost £300-£600 per unit.
Aluminium bi-fold doors run £3,000-£8,000 depending on width. Premium hardwood or powder-coated aluminium frames add 30-50% to glazing budgets.
Sustainable materials often cost more upfront but save on energy bills. High-performance insulation adds £15-£25 per square metre but helps cut heating costs.
Triple-glazed windows are about 40% pricier than double-glazing, but they do a lot for energy efficiency. Kitchen fittings are all over the map.
Basic cabinets and laminate worktops cost £3,000-£8,000, while bespoke cabinetry with quartz surfaces can hit £15,000-£30,000. Appliances tack on another £2,000-£10,000 depending on the brand.
Labour, Professional Fees, and Regulatory Requirements
Labour and professional services usually make up 50-60% of your total kitchen extension budget in London. Structural expertise, architectural design, and getting through local regs all cost real money, but you need them for a legal and high-quality job.
Labour Costs in London
London construction labour rates range from £150 to £250 per day for general builders. Specialist trades like electricians charge £200-£300 per day, and plumbers ask for £180-£280 per day.
Your total labour costs depend on how long your project takes and how complicated it is. A standard single-storey kitchen extension usually takes 8-12 weeks, which turns into £15,000-£40,000 in labour expenses.
London’s competitive market and higher living costs push these rates 20-30% above the UK average. Kitchen fitters charge separately for cabinets and worktops.
Expect £2,000-£5,000 for a professional kitchen installation, depending on how complicated your units are. Many contractors offer package quotes that bundle labour, which can simplify budgeting—but compare carefully.
Architect and Structural Engineer Fees
Architectural services for kitchen extensions cost £2,500-£8,000 in London. Local architects usually charge 8-12% of your total build costs, or fixed fees for smaller projects.
This covers initial designs, technical drawings, and planning application support. Structural engineer fees range from £800-£2,500, depending on size and complexity.
You’ll need structural calculations for load-bearing walls, foundation design, and steel beam specs. Some people also hire a quantity surveyor for £500-£1,500 to help control costs and negotiate with contractors.
Most projects need both an architect and a structural engineer. If you’re removing walls or adding weight to existing structures, you can’t skip the engineer.
Some architectural practices include basic structural design, but complicated projects usually need a separate specialist.
Planning Permission Considerations
A lot of single-storey kitchen extensions fall under permitted development rights, so you might avoid formal planning permission. But if you’re in a conservation area, listed building, or already have previous extensions, you’ll need to apply (costing £206-£462).
Your local council’s building regulations approval runs £500-£1,200 no matter what. This covers structural safety, fire regs, and energy efficiency.
London boroughs have their own quirks, especially when it comes to party walls in terraced and semi-detached homes. Party wall agreements cost £700-£1,500 if your extension affects neighbours.
Set aside an extra 10-15% of professional fees for random regulatory requirements or design tweaks requested by planning officers.
Building Regulations, Party Wall Agreements, and Legalities
Kitchen extensions in London need a few legal boxes checked beyond planning permission. You’ll need building regs approval for structural work, and if your extension touches a shared boundary, the Party Wall Act 1996 comes into play.
Understanding Building Regulations Approval
Building regs approval is a must for all kitchen extensions in London, no matter the size. This makes sure your extension meets standards for structural integrity, fire safety, ventilation, electrics, and insulation.
You’ll have to submit plans to your local authority building control or use an approved inspector. The process usually takes 5-8 weeks.
Expect to pay £800-£1,500 for building control fees, depending on size and complexity. Even if your extension is permitted development, you still need building regs approval.
Inspectors will visit your site at key moments—foundation work, damp-proofing, and final completion.
Here’s what the regulations cover:
- Structural stability – foundations, walls, roof
- Fire safety – escape routes, fire-resistant materials
- Drainage and waste – proper connection to existing systems
- Energy efficiency – insulation, glazing
- Ventilation – good air flow in the new space
Party Wall Agreements and Surveyor Roles
If your extension is built on or within three metres of a shared boundary, you have to serve a party wall notice to neighbours. This applies to terraced, semi-detached, and some detached properties in London.
The Party Wall Act 1996 protects both you and your neighbour. Serve notice at least two months before work starts for building on a party wall, or one month for excavations near a boundary.
Your neighbour can consent or dissent. If they dissent or don’t reply in 14 days, you’ll need a party wall surveyor.
You can use a single agreed surveyor (usually £700-£1,200) or both sides can appoint their own (costing £1,500-£2,500 total). RICS-qualified surveyors check the neighbour’s property condition and draw up a party wall award.
This document lays out what work you can do, when, and how to handle any damage.
UK Building Regulations Compliance
UK building regs set the minimum standards for your kitchen extension. Part L (conservation of fuel and power) requires U-values of 0.18 W/m²K for walls and 0.15 W/m²K for roofs in new extensions.
You need enough daylight—glazing should cover at least 20% of the floor area. Part M covers accessibility, so you’ll need level thresholds and enough space to move around.
Electrical work must comply with Part P, which usually means certification from a qualified electrician. Building control officers check things at critical stages.
They’ll look at foundations, damp-proofing, structural elements, and drainage before you cover them up. Final sign-off includes testing ventilation and checking energy efficiency calculations.
Hang onto all your certification documents—you’ll need them if you ever sell your property.
Cost Breakdown: Construction, Kitchen Fittings, and Additional Features
A kitchen extension in London comes down to three main cost areas: the structural build, the kitchen itself, and any premium upgrades you fancy. London prices usually run 15-25% higher than the UK average because of higher labour costs and stricter planning requirements.
Construction Costs and Core Works
The construction cost is usually the biggest part of your extension budget. For a standard 15-20m² single-storey rear extension, expect to pay £40,000-£60,000 just for the structural work. That covers groundworks, foundations, walls, roof, windows, doors, and plastering.
If you go for a timber frame, you might save 10-15% compared to traditional brick and block. It also speeds up the build. In outer London, basic construction costs about £1,200-£1,500 per square metre, but in central areas, it jumps to £1,800-£2,200 per square metre.
You’ll need damp-proof membranes, proper insulation, and good ventilation to meet building regs. Don’t forget about £300-£600 for building control fees and £500-£1,200 for structural engineer calculations. If you’re knocking down existing walls, add £1,500-£3,000 for steel beams and installation.
Kitchen Fitting and Appliance Costs
Kitchen installation eats up 30-40% of your total project budget. For a new extension kitchen, budget somewhere between £12,000 and £25,000 for a mid-range setup—units, worktops, and appliances included. Budget kitchens start at £6,000, while bespoke designs can easily top £25,000.
Labour for fitting the kitchen costs £2,200-£4,600 in most areas, but London fitters charge £250-£400 a day. Standard installation takes 5-10 days. You’ll also need electricians (£500-£1,900), plumbers (£300-£1,000), and maybe a Gas Safe engineer (£40-£75 per hour) for gas hobs.
| Component | Budget Range |
|---|---|
| Base units and cabinets | £2,000-£8,000 |
| Worktops (quartz/granite) | £1,500-£4,000 |
| Appliances | £1,500-£6,000 |
| Sink and taps | £200-£800 |
| Flooring and tiling | £1,000-£2,500 |
Premium Features: Underfloor Heating, Roof Lights, and Glazing
Underfloor heating brings comfort and value. Electric systems run £75-£100 per square metre, so a 20m² kitchen costs around £1,500-£2,000. Water-based systems are pricier upfront (£150-£200 per square metre) but cheaper to run in bigger spaces.
Roof lights can totally change the feel of an extension. Standard Velux-style units cost £600-£1,200 installed, while flat roof lights start at £800-£1,500. Structural roof lanterns range from £2,500-£6,000, depending on size and glazing.
Bi-fold or sliding doors are hugely popular. Expect to pay £1,200-£2,000 per metre width for aluminium bi-folds, or £800-£1,400 for uPVC. Triple-glazed doors add £200-£400 each but make a noticeable difference in thermal efficiency.
Strategies for Budgeting and Avoiding Cost Overruns
Kitchen extensions in London need solid financial planning. If you don’t want surprise expenses to mess up your project, you’ll want to set aside contingency funds, get detailed quotes from multiple contractors, and know how to react if costs start to spiral.
Contingency Budgets and Managing Hidden Costs
A contingency budget is your safety net for unexpected costs. Most experts say put aside 10-15% of your total project cost for surprises.
In London, older properties often hide problems like damp, dodgy wiring, or foundation issues that only show up once you start work. Your contingency fund covers these headaches so you don’t have to cut corners or halt the project.
Hidden costs can include:
- Planning permission fees (£200-£500)
- Building regs approval (£400-£800)
- Party wall agreements (£700-£1,500 per surveyor)
- Temporary kitchen setup
- Structural engineer fees (£500-£2,000)
Track these separately from your main budget. The Building Cost Information Service is handy for up-to-date London cost data.
Obtaining Accurate Quotes and Controlling Expenses
Always get written quotes from at least three contractors before you sign anything. Each quote should break down labour, materials, and timeline.
Detailed quotes make it easier to compare and spot where costs are sneaking in. Push for specifics—materials, brands, quantities. Vague estimates usually mean trouble later.
Fixed-price contracts are safer than day rates. They lock in costs and put some risk on the contractor. Attach a clear spec sheet listing every fixture and finish so there’s no confusion.
Set up payment milestones tied to finished work stages. This gives you some leverage, so you’re not paying for half-done jobs. Hold back 5-10% as retention until everything passes inspection.
Dealing with Cost Overruns
If costs start to blow past your budget, figure out if the extra expense is truly needed or just a “nice to have.” You can’t skip structural fixes or building regs, but fancy finishes can wait.
Talk to your contractor as soon as you notice costs creeping up. Ask for written explanations for any changes from the original quote. If it’s down to unforeseen structural issues or changes you requested, fair enough—but don’t pay for their mistakes.
When overruns hit, consider:
- Reducing scope: Do the essentials now, finish the rest later
- Sourcing materials yourself: Hunt for sales on appliances and fixtures
- Adjusting specs: Choose mid-range options that still work
Get all changes in writing. Don’t approve extra work verbally—it just leads to arguments later.
Alternative Options: Loft Conversions, Garage Conversions, and Kitchen Renovations
You don’t always need a kitchen extension to get more space. Loft conversions and garage conversions add square footage, while kitchen renovations can totally change your layout without major building work.
Comparing Loft Conversions and Kitchen Extensions
A loft conversion in London will set you back £30,000 to £60,000—about the same as a kitchen extension, which usually costs £30,000 to £50,000. The big difference? Loft conversions give you another bedroom or office upstairs, while kitchen extensions expand the heart of your home.
Dormer lofts start at around £35,000. Mansard conversions can go past £60,000. Most loft projects take 6-8 weeks.
Go for a kitchen extension if you need more space for cooking, eating, or hanging out with family. Loft conversions are better for extra bedrooms or work space, especially if you want to keep your garden. Both options usually boost your property value.
Garage Conversion as an Alternative
Garage conversions cost £8,000 to £20,000 in London, so they’re much cheaper than kitchen extensions. Since you’re working with what’s already there, you skip a lot of groundwork and structural faff. Most projects take 4-6 weeks.
A garage conversion uses your existing footprint—no lost garden or major foundation work. But you do lose parking and storage space for good.
This route works if you need a ground-floor bedroom, office, or playroom. It’s not ideal if you specifically want to make your kitchen bigger. Some homes can link a converted garage to the kitchen, but it depends on your layout.
Kitchen Renovations Without Extension
Kitchen renovations run £5,000 to £25,000 if you don’t extend. You can upgrade cabinets, worktops, and appliances without touching the walls. The job usually takes 2-4 weeks and causes less chaos than an extension.
Refacing cabinets costs £1,000 to £3,000. New worktops are £500 to £3,000. Swapping out appliances adds £2,000 to £5,000.
Smart design tweaks can make your kitchen feel bigger. Take down a non-structural wall between your kitchen and dining room to open things up. Better lighting and lighter colours help too. These changes don’t need planning permission and cost less than any extension or conversion.
Frequently Asked Questions
Kitchen extension projects in London can get complicated. Knowing the typical costs, timelines, and rules helps you prep for a successful extension.
What are the average costs per square metre for extending a kitchen in London in 2026?
In London, kitchen extension costs usually fall between £2,500 and £4,000 per square metre. The price depends on your materials, design complexity, and finish choices.
Basic extensions with standard materials are at the lower end. High-end projects with luxury kitchens, loads of glazing, and tricky structural work hit the top end.
Your actual cost per square metre comes down to your choices on fixtures, appliances, and structure. Location matters too—some boroughs are just pricier.
Which factors predominantly influence the price of a kitchen extension in London?
Size is the main factor—bigger extensions need more materials and labour. Structural changes, like removing load-bearing walls or adding steel beams, bump up the price.
Complex designs cost more. Open-plan layouts with big doors or sliders are pricier than simple, contained spaces.
Materials and finishes make a big difference. If you want premium worktops, fancy cabinetry, or luxury appliances, your budget will stretch.
Labour costs are higher in London than elsewhere in the UK. Builders and trades charge more because of living costs and demand.
Access can also affect pricing. If your site is tricky for deliveries or work, expect higher quotes. Party wall agreements and extra surveys might be needed too.
Are there any specific planning permissions required for building a kitchen extension in London?
Some kitchen extensions fall under permitted development, so you don’t need formal planning permission. But a lot of London boroughs remove these rights with Article 4 directions.
Your local planning authority decides if you need to apply. Usually, you’ll need architectural drawings, a design statement, and maybe drainage or acoustic reports.
All kitchen extensions need building regs approval, even if you don’t need planning permission. This checks for structural safety, insulation, electrics, and ventilation.
If your work affects a shared wall or foundation, you’ll need a party wall agreement. That means hiring a surveyor, which adds time and cost.
It’s worth checking with your planning department early. Saves you hassle and money down the line.
How does the size and complexity of the kitchen design affect the overall extension cost?
A 7.5m² extension costs about £25,000 to £40,000 for basic specs—just the shell, standard finishes, and a simple kitchen.
If you go up to 12m², expect £60,000 to £95,000. That gets you better glazing, higher-end fixtures, and a more practical layout.
A big 20m² extension can hit £110,000 to £190,000. These usually have open-plan designs, premium kitchens, and complex services.
Complex designs add costs, no doubt. Vaulted ceilings, roof lanterns, and lots of glazing need more structural support and expert fitting.
Open-plan layouts need more outlets, lighting, and sometimes acoustic tweaks than compact kitchens. Your layout choices definitely shape the final bill.
What potential hidden costs should homeowners account for when budgeting for a kitchen extension?
Building regulations approval fees and structural engineer consultations can really bump up your initial budget. These pros usually charge several thousand pounds, but they make sure your extension meets safety standards—so, not something you want to skip.
If your work affects neighbouring properties, you’ll probably need a party wall agreement. That means hiring a surveyor, which isn’t cheap, especially in London.
VAT sits at 20% and applies to both labour and materials. This tax can be a bit of a shock, so double-check if your contractor’s quote already includes VAT or if it’s going to sneak up on you later.
Unexpected structural issues have a habit of popping up once construction starts. It’s smart to set aside a contingency fund—maybe 10% to 20% of your total budget—just in case you hit a snag.
During construction, your kitchen will be out of action. You might end up setting up a makeshift cooking area or, let’s be honest, spending more on takeaways than usual.
Sometimes, utility connections and upgrades cost more than you’d think. New gas lines, electrical panel upgrades, or extra plumbing can all add thousands to the final bill.
Can you outline the anticipated timeline for completing a kitchen extension in London?
Kitchen extension projects in London usually take anywhere from 4 to 12 months, start to finish. If you’re lucky enough to have permitted development rights, things tend to move faster than if you’re stuck waiting on planning permission.
The design and planning phase tends to last about 6 to 12 weeks. You’ll spend this time meeting with architects, sorting out drawings, and getting those applications into your local authority.
Once you submit everything, planning permission decisions can take 8 to 13 weeks. Building regulations approval either happens at the same time or right after, which adds a bit more waiting before you can actually break ground.
Construction itself? That’s generally 8 to 16 weeks, but it really depends on how big and complicated your extension is. Bad weather, slow deliveries, or tricky site access can stretch things out longer than you’d hope.
Finishing touches like kitchen installation and decorating will tack on another 2 to 4 weeks. It’s always a good idea to get a detailed schedule with all the key milestones from your contractor before they start swinging hammers.
