Typical budget
£50,000 to £200,000+
Depends on extension type, specification, borough, and whether the project includes a new kitchen.
Create the extra space your home is missing. Without giving up the area that already works.
A well-planned extension can give you the bigger kitchen, brighter layout and calmer family space your current home is missing. We help London homeowners move from first idea to finished extension with clear guidance, realistic budgets and disciplined delivery.
£10M insured10-year workmanship guaranteeWeekly updates during build
Book your extension consultationTrusted by London homeowners
5-star rated service with verified review proof across Google, Houzz, and MyBuilder.
Google 5
My Builder 5
Best of Houzz Award
5 star rated and award winning renovation company
Quick Answer
A good extension should solve daily friction, not just add metres
The strongest extension projects do more than make the house bigger. They make the space lighter, easier to use, and more supportive of how family life actually works now.
Direct answer: most London house extensions sit somewhere between £50,000 and £200,000+, depending on the route you choose. Simpler rear extensions can often avoid full planning, while wraparound and double-storey schemes usually need more approvals and a longer timeline. The full journey is commonly 6 to 10 months from feasibility to handover, and the right route depends as much on your house and priorities as it does on budget.
Planning route
Many simpler rear extensions avoid full planning
Wraparounds, side extensions and many larger schemes usually need more planning work.
On-site build
12 to 24 weeks
Single-storey is usually shorter. Wraparound and double-storey schemes take longer.
Value upside
Often 10% to 20%
The best-performing extensions improve daily use now and make the home more desirable later.
Why Extend
Why London homeowners choose extensions instead of moving
The best reason to extend is rarely just square metres. It is usually about keeping the life you already like while removing the part of the house that keeps frustrating you.
Stay in the area that already works for you
For many London families, the real win is not just extra square metres. It is avoiding the cost, disruption and compromise of moving when the right street, school run or neighbourhood is already in place.
Fix the ground floor that is wearing you down
Most extensions are really about one thing: the kitchen feels cramped, the layout feels dark, or family life keeps colliding in the same few rooms. A good extension removes that pressure every day.
Improve daily life and future value at the same time
When the design improves light, flow and usability properly, the result is easier to enjoy now and easier to justify later if you ever sell. That makes the spend feel safer, not just bigger.
Costs
House extension costs by type in London
These planning-stage guide ranges help you sense-check affordability early, before you fall in love with the wrong extension route for your house or budget.
| Type | Typical budget | Build phase | Planning route |
|---|---|---|---|
| Single-storey rear extension | £50,000 to £95,000 | 12 to 16 weeks build | Often permitted development if kept within depth limits |
| Side return extension | £35,000 to £60,000 | 8 to 12 weeks build | Often permitted development on suitable terraces |
| Wraparound extension | £75,000 to £140,000 | 14 to 20 weeks build | Usually full planning |
| Double-storey extension | £100,000 to £200,000+ | 16 to 24 weeks build | Often more planning-heavy than single-storey routes |
| Kitchen extension with fit-out | £80,000 to £160,000 all-in | 12 to 20 weeks build | Depends on whether the structural route is rear, side return or wraparound |
Professional fees, structural design and approvals usually add 10% to 15% on top of the build cost, so the cheapest headline quote is rarely the true number.
Party wall matters, scaffold licences, temporary parking suspensions and drainage surprises can shift the budget if they are not surfaced early.
If the real goal is a kitchen-living transformation, the kitchen itself can add £15,000 to £60,000+ on top of the structural extension cost.
Types
Which extension route fits your house?
The right answer depends on your plot, your property type, how much transformation you actually need, and whether your real goal is more light, a better kitchen-living layout, or significant extra space on more than one floor.
£50,000 to £95,00012 to 16 weeks build
Single-storey rear extension
The classic route when you need a larger kitchen-diner, better garden connection and more light without changing the whole house.
Planning note: Often permitted development if kept within depth limits
£35,000 to £60,0008 to 12 weeks build
Side return extension
A powerful option for Victorian and Edwardian homes where a narrow side passage is holding back what the ground floor could become.
Planning note: Often permitted development on suitable terraces
£75,000 to £140,00014 to 20 weeks build
Wraparound extension
The strongest choice when you want a real transformation of the ground floor rather than a modest gain in square footage.
Planning note: Usually full planning
£100,000 to £200,000+16 to 24 weeks build
Double-storey extension
Best when one extra room is not enough and you want meaningful space both downstairs and upstairs in one project.
Planning note: Often more planning-heavy than single-storey routes
£80,000 to £160,000 all-in12 to 20 weeks build
Kitchen extension with fit-out
Ideal when the real goal is not just an extension, but a large open-plan kitchen-living space that changes how the whole house works.
Planning note: Depends on whether the structural route is rear, side return or wraparound
Proof
Real extension projects that make the decision feel safer
The best proof is not generic praise. It is seeing projects where the layout improved, communication stayed clear, and the finished result felt worth the disruption.
Rear extension + full renovationN19, North London
Rear extension and whole-home transformation in N19
This project captures what most homeowners are actually buying when they extend: not just extra space, but a calmer layout, better natural light, and the feeling that the whole home now works properly together.
“The team managed the project with clarity and delivered a finish that feels premium in every room.”
- Rear extension integrated cleanly into the existing house
- Brighter kitchen-living space with stronger day-to-day flow
- Weekly progress updates to keep decisions and expectations clear
N19 Homeowner
Client testimonial
Side return extensionMore light, better circulation
Side return kitchen extension in E7
A narrow galley layout became a brighter and more usable family kitchen with stronger connection to the garden.
“The extension has transformed how we use the house day to day and the finish feels genuinely premium.”
E7 Homeowner
Client testimonial
Extension + renovationA more social family layout
Kitchen extension and renovation in N8
A structural extension project that created a larger and more sociable kitchen-living zone for modern family life.
“The build was organised, communication was clear, and the transformation feels substantial.”
N8 Homeowner
Client testimonial
Process
How we keep extension projects under control
Extension projects usually become stressful when the budget is vague, the drawings are disconnected from build reality, or communication fades once work starts. This process is designed to prevent exactly that.
Step 1
Feasibility and budget first
Before drawings gather momentum, we pressure-test what makes sense for the house, the planning context and the level of spend you are genuinely comfortable with.
Step 2
Design the extension around real living
The goal is not to bolt on square metres. It is to create better light, flow, storage and a ground floor that feels easier to live in every day.
Step 3
Approvals and pre-construction clarity
Planning, building regulations, structural input and sequencing all need to line up before site starts. That is what reduces the nasty surprises clients usually fear.
Step 4
Build with weekly visibility
You should know what is happening, what decisions are needed, and whether the programme is holding. Communication is part of the service, not a favour.
Step 5
Snagging and handover
The job should finish with detail, not drift. We close out with quality checks, snagging discipline and a handover you can feel safe signing off.
Guarantees that protect the work after handover
When you invest heavily in your home, you should know what happens after the builders leave. Our workmanship guarantees are there to give you clear protection and peace of mind.
10 years
Extension and loft conversion guarantee
2 years
Bathroom fitting and renovation guarantee
2 years
Kitchen fitting and renovation guarantee
1 year
Painting and decorating guarantee
Want the full guarantee breakdown?
Read it hereFAQ
Frequently Asked Questions
- Most London house extensions sit somewhere between roughly £50,000 and £200,000+, depending on the type. Side returns are usually the lightest route, rear extensions are the most common, and wraparound or double-storey schemes sit at the heavier end because they involve more structure, approvals and programme time. If the project also includes a new kitchen, that can materially increase the all-in budget.
- Not always. Many simpler rear extensions can proceed under permitted development if they stay within the relevant size limits, but wraparound, side, conservation-area and more ambitious schemes usually need more planning input. We check that early, because getting the planning route wrong at the start is one of the easiest ways for an extension project to become slower and more stressful than it needs to be.
- The on-site build phase is often around 12 to 24 weeks depending on the type, but the full journey including design, approvals, party wall matters and pre-construction coordination is usually closer to 6 to 10 months. That is why a realistic early plan matters more than a seductive start-date promise.
- For many London homeowners, yes. If you already like the street, the area and the basic house, extending can be a smarter use of money than paying stamp duty, agent fees, legal costs and the upheaval of moving. The real question is whether your house can be improved in the specific way you need without overspending for the area.
- It depends on the plot and the goal, but rear and side return extensions are often the strongest fit for London terraces. If the side passage exists and the kitchen feels cramped, a side return or wraparound can transform the whole ground floor far more effectively than simply extending straight out the back.
- Yes. In fact, many of the strongest extension projects combine the structural build with kitchen installation, layout reconfiguration and selected internal upgrades so the finished home feels coherent rather than half-old and half-new.
Useful Reading
The extension guides worth reading before you commit
If you are still comparing routes, budgets, planning risk or likely return, start with these. They will help you make a better decision before you speak to anyone.
House extensions London 2026: the complete guide
The best starting point if you want the bigger picture on cost, planning, process, ROI and extension routes in London.
House extension types compared
Use this to compare rear, side return, wraparound, double-storey and kitchen-extension routes before you pick one too early.
How much value a house extension adds in London
Useful if you are trying to balance emotional motivation with resale logic and want a clearer sense of likely return.
How to finance an extension in London
Covers remortgaging, further advances, budgeting realism and the financial case for improving versus moving.
House extension mistakes London homeowners make
Read this if you want to understand where budgets drift, planning assumptions go wrong, or a supposedly simple extension becomes stressful.
Next Step
If extending feels like the right route, start with a realistic conversation
A useful first conversation should tell you whether the extension idea makes sense for your house, what the realistic budget range looks like, and whether planning, layout or structural constraints are likely to shape the route before you spend too much energy on the wrong plan.