Area guide · N9 & N18
House Extensions in Edmonton (N9 & N18)
Planning a house extension in Edmonton? We design, gain planning permission and build extensions and loft conversions across Lower Edmonton, Upper Edmonton and the streets around Edmonton Green. Most single-storey rear extensions here cost £40,000–£80,000 to build — comfortably under the North London average — applications go through Enfield Council, and the most-approved project type right now is the prior-approval rear extension, with 6m schemes sailing through in N9 and N18. Get us round for a free site visit and we'll spell out what your street supports.
Live planning data
What Enfield Council is actually approving right now
We track every residential planning decision across North London — so instead of guessing what your council will accept, you can see it. And here's the headline: Edmonton is currently the single busiest town in our entire tracker. In the most recent two-week decision window, 38 schemes were approved across N9 and N18 — more than any other town we cover — out of 113 residential approvals across the borough of Enfield as a whole. Real examples from that list:
- 15 Coniston Gardens, N9 — householder extension approved via the prior-approval route
- 32 Hudson Way, N9 — householder extension approved via the prior-approval route
The pattern behind the numbers is unmissable: prior-approval rear extensions are sailing through Edmonton. The larger home extension scheme allows a rear extension of up to 6m on a terrace or semi (8m on a detached house) through a light-touch neighbour-consultation process rather than a full planning application — and Edmonton homeowners are using it street after street. If that's the shape of your project, you're pushing at an open door. We design to exactly that grain.
Source: Enfield Council's publicly available planning decisions. The examples describe the borough's approval pattern, not our own jobs — and every application is weighed on its own particulars.
Local knowledge
Edmonton's housing stock — and what works on each
Edmonton is the value belt of our patch — and that's precisely what makes it one of the smartest places in North London to extend. Three broad markets, one common thread: space is cheaper to build here than almost anywhere else we cover, and the value it adds is just as real.
The Victorian terraces of Lower Edmonton (N9). Classic two-storey terraces with rear additions and side alleys. The strongest moves are the side-return extension (£30,000–£55,000), turning a narrow galley kitchen into a full-width kitchen-diner, and the prior-approval 6m rear extension — the exact scheme type dominating Enfield's current approvals list. Party wall agreements with both neighbours are usually needed; we manage that as part of the job.
The interwar belt (Upper Edmonton, N18 and the Great Cambridge Road corridor). Bay-fronted 1930s semis and terraces with hipped roofs and proper gardens. Here the hip-to-gable loft conversion with rear dormer (£48,000–£80,000) adds a double bedroom and en-suite without touching the garden, and pairs beautifully with a single-storey rear extension below — plenty of owners phase the two.
Post-war and ex-local-authority family homes. Solidly built, often with wider plots and garages — which makes the garage conversion (£16,000–£30,000) the cheapest extra room in Edmonton, and keeps the rear garden free for a kitchen extension later.
The value-add story. Build costs in Edmonton run 10–15% below the North London baseline, yet a well-designed kitchen extension or loft transforms exactly the kind of three-bed family house this area is full of. The result: an extension in N9 or N18 adds proportionally more than almost anywhere else we cover. If you're weighing "move vs improve" anywhere in our patch, Edmonton is where the maths tilts hardest towards improve.
Every street is different. That's the point.
We design to Edmonton's stock and to what the council demonstrably approves — not to a template. A free site visit tells you what your house can take.
Get my free estimateHonest numbers
What a house extension costs in Edmonton in 2026
These are realistic all-in build ranges for Edmonton — labour and materials to a good standard, excluding VAT, professional fees and kitchen fit-out:
| Extension type | Typical Edmonton cost | On-site time | Usual planning route |
|---|---|---|---|
| Side-return extension | £30,000 – £55,000 | 2–3 months | Often permitted development |
| Single-storey rear | £40,000 – £80,000 | 3–4 months | Often permitted development |
| Kitchen extension (incl. mid-range kitchen) | £48,000 – £95,000 | 3–4 months | Often permitted development |
| Hip-to-gable loft + rear dormer | £48,000 – £80,000 | 6–10 weeks | Usually permitted development |
| Wrap-around extension | £60,000 – £120,000 | 4–6 months | Full application |
| Double-storey rear | £65,000 – £140,000 | 5–7 months | Full application |
| Garage conversion | £16,000 – £30,000 | 4–6 weeks | Usually permitted development |
As a rule of thumb, Edmonton build costs run £2,400–£3,700 per square metre — 10–15% below the wider North London rate of £2,800–£4,200/m², helped by straightforward stock and plots that are easier to work on. To put that in project terms, a 20m² rear extension works out at £50,000–£70,000 of build cost. The quote you receive after the free site visit is fixed and itemised throughout — the price stays put from contract to completion.
Permissions, handled
Planning permission in Edmonton — what you need to know
Most Edmonton extensions don't need a full planning application. Out of the box, permitted development hands semis and terraces 3m of single-storey rear depth and detached houses 4m — then the larger home scheme, via prior approval, takes those to 6m and 8m, which is exactly the route Edmonton's current approvals are flowing through. Loft conversions enjoy a generous volume allowance, so most hip-to-gable and dormer schemes proceed without a full application too.
Where you do need permission: double-storey rear extensions, wrap-arounds, anything on flats and maisonettes, and houses where previous owners have already used up permitted development rights — common on terraces extended in decades past. Expect a standard householder application to spend roughly eight weeks with Enfield Council before a decision; prior-approval determinations are typically quicker.
Party walls: almost all of N9 and N18 is terraced or semi-detached, so the Party Wall Act applies to the great majority of projects — budget £1,000–£2,500 per affected neighbour if surveyors are appointed, and start the conversation early. We prepare the notices as part of the job.
Conservation: permitted development rights are restricted in conservation areas, so we check your address against the council's conservation map before any design work starts — no surprises halfway through.
Our approach: we design to what Enfield Council demonstrably approves — and in Edmonton that means making maximum use of the prior-approval route. Where a Lawful Development Certificate is the smarter way to lock in your position, we'll say so and sort it — leaving you with paperwork no buyer's conveyancer can pick holes in.
How it works
How it works
- Free site visit — we tour your Edmonton terrace or semi, hear your plans, and level with you about feasibility, cost and the planning route.
- Design & drawings — working drawings and 3D visuals built around the house you own and the space you need from it.
- Planning, handled — application prepared, lodged with Enfield Council and managed by us until the decision lands.
- Fixed-price build — our vetted North London team carries out the work, gets building control's sign-off and leaves the site spotless.
Our work
Recent work near Edmonton
Our build team's recent North London projects include a full house transformation taking a family home from 120m² to 360m², a 55m² garden room with kitchen and bathroom, and an Edwardian conversion in Finchley. Bring it up when we visit and we'll pull together the projects that line up with yours.
Questions, answered
Edmonton extension FAQs
How much does a house extension cost in Edmonton?
Less than almost anywhere else we cover: roughly £40,000–£80,000 for a single-storey rear extension, £48,000–£80,000 for a hip-to-gable loft and £16,000–£30,000 for a garage conversion, excluding VAT and fees. Edmonton build rates run £2,400–£3,700/m² — 10–15% under the North London average.
Is an extension actually worth it on an Edmonton terrace?
Arguably more so than anywhere else in our patch. Because build costs sit below the North London baseline while demand for finished family homes in N9 and N18 stays strong, an extension here adds proportionally more value than almost any other area we cover. We'll talk honest numbers for your street at the site visit.
What's the prior-approval route everyone in N9 and N18 seems to be using?
The larger home extension scheme: a neighbour-consultation process that lets terraces and semis extend up to 6m to the rear (8m for detached homes) without a full planning application. It's the most-approved scheme type in Edmonton right now — 38 N9/N18 approvals came through in the latest window we tracked, with prior-approval rears like Coniston Gardens and Hudson Way leading the way.
Do I need full planning permission for my Edmonton extension?
Often not. Standard rear extensions and most lofts proceed under permitted development or prior approval. You'll need a full application for double-storey schemes, wrap-arounds and any work to flats or maisonettes — and if your address falls in a conservation area, permitted development rights are restricted, so we check the council's map first.
How long will Enfield Council take to decide?
Around eight weeks for a standard householder application once validated; prior-approval and lawful development certificate routes are usually quicker. Design and drawings before submission typically take 4–8 weeks, so allow three to four months from first sketch to a green light.
My neighbours are attached on both sides — what about party walls?
Standard for Edmonton terraces: you'll serve notice on both neighbours, and if surveyors are appointed, budget £1,000–£2,500 per neighbour. Most agreements are amicable when the conversation starts early — we prepare all the notices for you as part of the job.
Nearby areas we cover
What clients say
Rated 5.0 on Google
“Used The Extension Company for a loft conversion on our semi detached in Barnet and couldn't be happier. They explained what was possible at the first visit, sorted the planning side, and gave a fixed price with no surprises at the end.…” read the full review
“Really impressed with the entire project. The side extension and conservatory have been finished to a very high standard and the team made the process straight forward and stress-free. It’s transformed the space and added so much value, would definitely recommend.”
“Brilliant experience with the extension company, transparent from the word go. Completed a double story extension for me and I couldn’t be more pleased. Thank you”
“I got the extension company to do a bathroom refurb for us a January they done a great job they managed to fit in a large shower as well as a bath”
Reviews shown word for word from our Google profile. Read all 8 reviews on Google
Free site visit
Ready to see what's possible on your street?
Free site visit anywhere in Edmonton, honest feasibility advice and a fixed, itemised price — design, planning and build handled end to end by the Pine Grove team.
020 3051 9430Lines answered weekdays 8am to 6pmEvery area we cover
Browse the full areas guide →Enfield & the EN heartland
Cockfosters · Oakwood · Southgate · Winchmore Hill · Palmers Green · Enfield · Edmonton
Barnet borough
Barnet · East Barnet · New Barnet · Hadley Wood · Arkley · Monken Hadley · Hampstead Garden Suburb · Whetstone · Totteridge · Finchley · East Finchley · North Finchley · Friern Barnet · Hendon · Golders Green · Mill Hill · Edgware
Hertfordshire border
Potters Bar · Radlett · Shenley · Elstree & Letchmore Heath · Northaw · Cuffley · Cheshunt · Waltham Cross · Brookmans Park · Hatfield · Hoddesdon
St Albans & the Chilterns
Harpenden · St Albans · Chorleywood & the Chalfonts · Gerrards Cross · Beaconsfield
Haringey & the N postcodes
Muswell Hill · Highgate · Crouch End · Hornsey · Wood Green · Tottenham
North-west London
East & the Essex edge
Stoke Newington · Walthamstow · Chingford · Loughton · Chigwell · Theydon Bois & Epping · Hutton Mount & Shenfield
South-west London & Surrey
Richmond · Wimbledon Village · Esher · Oxshott · Cobham · St George's Hill · Wentworth & Virginia Water
South London & the Surrey downs
Chislehurst · Purley & the Webb Estate · Banstead · Kingswood & Walton-on-the-Hill