Area guide · N12
House Extensions in North Finchley (N12)
Planning a house extension in North Finchley? N12 is a patch we know street by street — the terraces near Tally Ho corner, the 1930s semis and Edwardian avenues out along Woodhouse Road, Woodside Park's leafier grid — and we handle the whole journey: design, permission, build. Costs first: a single-storey rear typically builds for £45,000–£90,000, with Barnet Council deciding the application. The planning decisions on this page come from Barnet's Woodhouse ward, the part of N12 around Woodhouse Road and Torrington Park. Get a free site visit in the diary and we'll translate all of that into what your own house can do.
Planning in North Finchley
What Barnet Council has approved in North Finchley
Rather than guess at the council's mood, we read its published decisions. The dated list here is Woodhouse ward's: the part of N12 north and east of Tally Ho corner, taking in both sides of the High Road and running out through Woodhouse Road and Torrington Park towards Summers Lane, with approvals and refusals side by side.
Owners in this ward extend in every direction, and the list shows it: rear dormers and hip-to-gables on the roofs, single-storey rears and side additions at ground level, and front extensions, which fall outside permitted development (a small porch aside) and always need a full application. Watch for the larger-home prior approvals among them. A 6m rear through that route is decided on its effect on the neighbours, so where one is refused, a shallower or lower version is often the way back.
Recent planning decisions around North Finchley
Extension, loft and basement applications decided in Barnet's Woodhouse ward, 23 Sep 2025 to 22 Sep 2026.
The newest decisions in those wards
- ApprovedSep 2026
Addington Drive, N12
Single story front and side extension with 2no. rooflights incorporating new front porch. Single storey rear conservatory
26/2693/HSE · Barnet CouncilHouseholder application
- ApprovedSep 2026
Grove Road, N12
Single storey rear extension with a proposed depth of 6 metres, maximum height of 3.4 metres and eaves height of 2.7 metres.
26/2970/PNH · Barnet CouncilPrior approval, larger home extension
- RefusedSep 2026
Summers Lane, N12
Single storey rear extension with a proposed depth of 5.00 metres, maximum height of 3.71 metres and eaves height of 2.76 metres…
26/2925/PNH · Barnet CouncilPrior approval, larger home extension
- RefusedAug 2026
Friern Watch Avenue, N12
Roof extension involving hip-to-gable roof enlargement with rear dormer window, Juliet balcony, removal of the existing chimney stack…
26/3006/192 · Barnet CouncilLawful development certificate
- ApprovedAug 2026
Woodhouse Road, N12
Roof extension with rear dormer window and 3no. front facing rooflights following the demolition of existing chimney stack
26/2846/192 · Barnet CouncilLawful development certificate
- ApprovedAug 2026
Ashurst Road, N12
Single storey side extension
26/2372/HSE · Barnet CouncilHouseholder application
- ApprovedAug 2026
Petworth Road, N12
Roof extension involving rear dormer window with juliette balcony, 2no. front facing rooflights and new side gable window. Erection of a…
26/2290/192 · Barnet CouncilLawful development certificate
- ApprovedAug 2026
Fredericks Place, N12
Single storey rear infill extension. Roof extension involving raising of the ridge height, rear dormer window with juliette balcony and…
26/2344/HSE · Barnet CouncilHouseholder application
Look a reference up on the council’s own register: Barnet Council planning search.
Source: GLA Planning London Datahub, 23 Sep 2025 – 22 Sep 2026. Data updated September 2026. This list last changed 23 September 2026. The datahub can lag a council’s own register by a few weeks.
These are council decisions on applications in these wards, shown as local planning context. They are not necessarily projects undertaken by us, and they are not our approval rate. Planning outcomes depend on your specific property and proposal.
N12 is five wards, not one
North Finchley doesn't map onto a single ward. N12 is split between five of Barnet's: Woodhouse, whose decisions are on this page, plus West Finchley, Totteridge & Woodside, Whetstone and Friern Barnet. That matters when you read any list of local decisions.
Tally Ho corner and the Ballards Lane side fall in West Finchley ward, so their decisions sit with Church End's on our Finchley page. That ward also holds the Moss Hall Crescent conservation area, where an Article 4 direction takes away the right to extend.
Woodside Park is part of the Totteridge & Woodside ward, and its decisions appear on our Totteridge page. The streets towards Whetstone and Friern Barnet have pages of their own too. Barnet decides all of them; what differs is which list shows your neighbours' applications.
Local knowledge
North Finchley's housing stock — and what works on each
North Finchley is two markets stitched together at Tally Ho corner — Victorian terrace streets close to the town centre, Metroland semis further out — with Woodside Park adding a leafier third.
The terraces near Tally Ho and the High Road. Close to the town centre, the terrace streets respond to two classic moves. First, a side-return extension (£35,000–£65,000): the kitchen swallows the alley beside it and comes out a full-width kitchen-diner. Second, a loft conversion with rear dormer, supplying the bedroom and en-suite that turn a two-up-two-down into a family home.
The 1930s semi grid. Here the bay-fronted, hipped-roof semis take over, and with them the obvious roof scheme: the hip-to-gable loft with rear dormer (£55,000–£90,000). Pair it with a single-storey rear (£45,000–£90,000) that opens the kitchen to the garden and you've covered the two moves this housing was built for.
The avenues — Torrington Park, Friern Watch Avenue and their neighbours. Generous Edwardian and interwar houses in Woodhouse ward, where multi-part schemes stack several moves into one consent: a part single-, part two-storey side and rear extension, say, with a new porch at the front.
Woodside Park. Further west, the plots widen and the houses grow — large semis and detached homes with the elbow room for a double-storey rear (£75,000–£160,000) or a wrap-around (£70,000–£140,000) without feeling crowded.
Every street is different. That's the point.
We design to North Finchley'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 North Finchley in 2026
Cost-wise, N12 is refreshingly unremarkable: standard North London rates, no postcode premium, no discount. What follows are believable build figures — labour and materials done properly, with VAT, professional fees and kitchen fit-out accounted for separately:
| Extension type | Typical North Finchley cost | On-site time | Usual planning route |
|---|---|---|---|
| Side-return extension | £35,000 – £65,000 | 2–3 months | Often permitted development |
| Single-storey rear | £45,000 – £90,000 | 3–4 months | Often permitted development |
| Kitchen extension (incl. mid-range kitchen) | £55,000 – £110,000 | 3–4 months | Often permitted development |
| Hip-to-gable loft + rear dormer | £55,000 – £90,000 | 6–10 weeks | Usually permitted development |
| Wrap-around extension | £70,000 – £140,000 | 4–6 months | Full application |
| Double-storey rear | £75,000 – £160,000 | 5–7 months | Full application |
| Garage conversion | £18,000 – £35,000 | 4–6 weeks | Usually permitted development |
The baseline arithmetic is £2,800–£4,200 per square metre, so a 23m² rear extension comes out around £64,000–£97,000 to build. We don't deal in moving targets: after the free site visit your quote is fixed and itemised, and that's the sum you'll actually pay.
Permissions, handled
Planning permission in North Finchley — what you need to know
A surprising amount of N12 work never sees a full planning application. As of right, permitted development allows a 3m-deep single-storey rear on semis and terraces and 4m on detached houses; clear the prior-approval hurdle of the larger home extension scheme and you can build to 6m, or 8m detached. Roof space is generous too — the loft volume allowance is why many hip-to-gable schemes need no full application.
Permission becomes essential for two-storey and wrap-around schemes, for flats, and for front extensions, which sit outside permitted development apart from a small porch. Well-proportioned front additions with pitched roofs are winnable in N12, which surprises plenty of owners who'd written the idea off. As for conservation status, that's checked — address against council conservation map — during the free consultation, never assumed.
Decision timing? A standard householder application generally spends about eight weeks with Barnet once validated. Because N12 is a place of shared walls, party wall procedure features in most builds — set aside £1,000–£2,500 per affected neighbour where surveyors are appointed, and warm the neighbours up early; drafting and serving the notices is part of our job. Anything built under permitted development gets a Lawful Development Certificate from us as standard, so there's never an argument about it at sale time. For the wider picture, our guide to extending in North London sets Barnet's rules against its neighbours'.
How it works
How it works
- Free site visit — we meet you at the house, whether that's a terrace near Tally Ho or a Woodside Park semi, and give a straight assessment of feasibility, cost and consent route.
- Design & drawings — drawings and 3D visuals that take their cue from your house's layout and how your family runs.
- Planning, handled — application drafted, submitted to Barnet Council and managed by us until the decision notice arrives.
- Fixed-price build — our own North London build team delivers the build, building control signs it off, and the handover is left immaculate.
Our work
Recent work near North Finchley
Lately the build team has completed a full house transformation in Hadley Wood, taking a family home from 120m² to 360m² — it's written up as our Hadley Wood case study. At your North Finchley site visit, just ask and we'll walk you through it.
Questions, answered
North Finchley extension FAQs
What kinds of extension get approved around North Finchley?
On N12's 1930s semis, the hip-to-gable loft conversion and the single-storey rear are the natural moves. Woodhouse ward's decisions also take in dormers, multi-part side and rear schemes and front extensions, so the council is dealing with plenty of variety here.
Can I extend the front of my house in N12?
Front additions sit outside permitted development, so you'll need full permission. Designed in proportion with the street, usually with a pitched roof that matches the house, they can pass; a bulky flat-roofed box across the frontage is far harder to get through.
What should a 1930s semi owner here budget?
£55,000–£90,000 for a hip-to-gable loft with rear dormer, £45,000–£90,000 for a single-storey rear — and doing both, phased, transforms the house for well under the cost of trading up in N12.
Do two-storey side and rear schemes get approved in North Finchley?
They do, on the avenues where plots allow. They need a full application, neighbour amenity is the key test, and budget £75,000–£160,000 for the build.
When could we realistically start on site?
Design and drawings take 4–8 weeks, Barnet's decision around eight more, and party wall notices run alongside — so most projects break ground 3–5 months after the first visit. Lofts done under permitted development can move faster.
Do you cover Woodside Park and the rest of N12?
All of it — Woodside Park, the terraces near Tally Ho, the avenues off Woodhouse Road and everything between, plus neighbouring Whetstone and Friern Barnet. Woodside Park's own council decisions are on our Totteridge page, because that's the ward it sits in.
What we build in North Finchley
The same team designs, gets planning and builds — one fixed, itemised price whichever route your North Finchley project takes.
- Kitchen extensions in North Finchley
- Side return extensions in North Finchley
- Double-storey & wrap-around in North Finchley
- Loft conversions in North Finchley
- Orangeries in North Finchley
- Garden rooms & offices in North Finchley
Checking the rules for North Finchley first?
Nearby areas we cover
What clients say
Rated 5.0 on Google
“The Extension Company built a 5m single storey rear extension on our Victorian terrace in Crouch End. Went down the permitted development route so no planning application needed, which they explained up front and saved us months. Kitchen-diner now opens onto the garden with sliding doors. £87k all in, matched the quote.”
“From the initial site visit onwards to my property in Barnet, we felt that the team actually listened to what we wanted. They suggested a few changes to the layout that we hadn't considered, and those changes have made a huge difference. Would definitely use again and recommend”
“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. The hip-to-gable and rear dormer gave us a big double bedroom with an en-suite. Tidy, professional and finished on schedule. Would recommend to anyone in North London thinking about a loft conversion.”
“We had been putting off our loft conversion for years because the whole process felt overwhelming. The team made it much easier than expected and handled the drawings, planning and build for us. We now have a lovely extra bedroom and shower room.”
“Our wrap-around extension has completely transformed the ground floor. We now have the open plan kitchen and family space we wanted without losing all of the garden. Thanks to everyone involved.”
“Really pleased with the work from The Extension Company. We had our extension done in Hampstead and the whole experience was excellent. Great communication from start to finish, The quality of the finish is excellent and we’re really happy with the result. Would definitely recommend them if you’re thinking about an extension.”
Reviews shown word for word from our Google profile. See 9 more client reviews · Read all 16 reviews on Google
Free site visit
Ready to see what's possible on your street?
Free site visit anywhere in North Finchley, honest feasibility advice and a fixed, itemised price — design, planning and build handled end to end by the Pine Grove team.
020 3051 9430Lines open every day, 9am to 8pmMore of North London
Enfield borough
Cockfosters · Oakwood · Southgate · Winchmore Hill · Palmers Green · Enfield · Edmonton · Hadley Wood
Barnet borough
Barnet · East Barnet · New Barnet · Arkley · Monken Hadley · Hampstead Garden Suburb · Whetstone · Totteridge · Finchley · East Finchley · North Finchley · Friern Barnet · Hendon · Golders Green · Mill Hill · Edgware
Haringey borough
Muswell Hill · Highgate · Crouch End · Hornsey · Wood Green · Tottenham
Camden borough
Hackney borough
Hertfordshire border
Potters Bar · Radlett · Shenley · Elstree & Letchmore Heath · Northaw · Cuffley · Brookmans Park · Borehamwood