Area guide · HA8
House Extensions in Edgware (HA8)
Planning a house extension in Edgware? We design, gain planning permission and build across HA8 — and we know which council you're dealing with, because Edgware has two: Barnet east of the High Street, Harrow to the west. A single-storey rear extension builds here for £45,000–£90,000, and the most-approved scheme in HA8 right now is the hip-to-gable loft with rear dormer — the natural move for Edgware's wall-to-wall 1930s semis. One free site visit and you'll have a clear, honest read on what your street allows.
Live planning data
What the councils are approving in Edgware right now
Every residential planning decision in North London ends up in our tracker — so rather than speculating about what your council will wear, you can read the answer off the record. In the most recent two-week decision window there were 10 residential approvals in HA8, against 63 across Barnet and 9 across Harrow as a whole. These are real Edgware approvals from the Barnet side:
- 92 St Margarets Road, HA8 — hip-to-gable roof extension with rear dormer and two front rooflights
- 121A Fairfield Crescent, HA8 — single-storey rear extension
- 58 Harrowes Meade, HA8 — hip-to-gable roof extension with rear dormer
Two hip-to-gables out of three is no accident. Edgware's hipped-roof semis are the natural habitat of the loft conversion, and the borough-wide data says the same thing: lofts and single-storey rears dominate Barnet's approvals. If your project looks like the ones above, you're in well-trodden territory — and we design to that grain.
Source: decision records published by Barnet and Harrow Councils. They demonstrate the local mood, nothing more — these aren't our schemes, and every application is determined on its own merits.
Local knowledge
Edgware's housing stock — and what works on each
The 1930s semi heartland. Edgware is Metroland at full strength: street after street of hipped-roof, bay-fronted semis built when the Underground arrived, with side passages and the generous gardens interwar builders allowed. The playbook writes itself. A hip-to-gable loft with rear dormer (£55,000–£90,000) converts the dead hip into a double bedroom and en-suite. A single-storey rear extension (£45,000–£90,000) — 3m under standard permitted development, up to 6m with larger-home prior approval — turns the back of the house into one big kitchen-diner. Do both and a three-bed semi becomes a five-bed family home. And because HA8 build costs sit at the standard North London baseline while the space gained is worth real money, Edgware is one of the strongest value-add markets in our patch.
West of the High Street — the Harrow side. Cross the High Street and the houses barely change, but the council does: the western side of Edgware, running towards Canons Park, falls under Harrow Council rather than Barnet. National permitted development rules are identical on both sides; what changes is the local process, the policies quoted in decisions and the forms. Harrow approved 9 residential schemes in the same recent window, so the machinery is moving there too. We submit to the right authority with the right framing — you don't have to think about it.
Flats and maisonettes around the centre. Around the station and the town centre, a fair slice of HA8 lives in flats and maisonettes — where permitted development doesn't apply at all. Extensions and loft schemes need full planning plus the freeholder's agreement; we confirm the position before designing.
Every street is different. That's the point.
We design to Edgware'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 Edgware in 2026
For Edgware, sensible all-in build budgets run as follows — good-quality labour and materials, with VAT, professional fees and kitchen fit-out charged separately:
| Extension type | Typical Edgware 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 |
Edgware sits on standard North London rates of £2,800–£4,200 per square metre — and that's the quiet advantage here: baseline build costs in a well-connected suburb, which is why extensions in HA8 so often cost less than the value of the space they create. Take a 24m² rear scheme: somewhere between £67,000 and £101,000 of build cost at those rates. The price we give you after a free site visit is fixed and itemised, with no padding and no surprises.
Permissions, handled
Planning permission in Edgware — Barnet or Harrow?
The first question on any Edgware project: which side of the High Street are you on? East and you're in Barnet; west, towards Canons Park, and you're in Harrow. The answer changes where we apply, not what's physically possible — permitted development rules are national.
Most Edgware extensions don't need a full application. Your automatic allowance is 3m of single-storey rear depth on a semi or terrace and 4m on a detached house; go through prior approval under the larger home extension scheme and those figures become 6m and 8m. Loft conversions enjoy a generous volume allowance, which is why hip-to-gable schemes like those on St Margarets Road and Harrowes Meade pass repeatedly. Whichever authority you fall under, a standard householder application should be decided within roughly eight weeks.
You will need permission for: double-storey and wrap-around schemes, flats and maisonettes, anything in a conservation area — where permitted development rights are restricted; we check your address against the council's conservation map — and houses where earlier owners have already used up the PD allowance.
Party walls: Edgware's semis mean the Party Wall Act applies to almost every project — budget £1,000–£2,500 per affected neighbour if surveyors are appointed. We serve the notices as part of the job.
Our approach: we design to what the decision data shows passing, and when lawful development is the cleverer route we'll get the certificate sorted — solid paperwork that future buyers' solicitors will thank you for.
How it works
How it works
- Free site visit — we visit your HA8 home, settle the Barnet-or-Harrow question on the spot, and give plain-spoken advice on feasibility, cost and route.
- Design & drawings — considered plans and 3D visuals that work with your semi's proportions and the way you live in it.
- Planning, handled — we assemble and submit the full application to Barnet or Harrow — whichever side of the High Street you're on — and drive it to a decision.
- Fixed-price build — our trusted North London builders see it through, with building control sign-off and a clean handover at the end.
Our work
Recent work near Edgware
North London highlights from our build team lately: 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 nearby Finchley. Flag what you're planning at the site visit and we'll show you the closest comparisons.
Questions, answered
Edgware extension FAQs
How much is a house extension in Edgware?
£45,000–£90,000 for a single-storey rear, £55,000–£90,000 for a hip-to-gable loft and £18,000–£35,000 for a garage conversion — excluding VAT and fees, at North London baseline rates of £2,800–£4,200 per square metre. HA8 doesn't carry the premium that Hampstead or Golders Green does, which is exactly why the value-add stacks up.
Barnet or Harrow — who decides my application?
It depends which side of Edgware High Street you're on: broadly, east is Barnet and west, towards Canons Park, is Harrow. We confirm it against the council boundary at the site visit and submit to the right authority — permitted development rules are the same on both sides.
Is one council tougher than the other?
The national permitted development framework is identical either side, so straightforward rears and lofts follow the same rules wherever you are in HA8. Local policies and process differ in the details, and both machines are demonstrably moving — 63 residential approvals across Barnet and 9 across Harrow in the latest two-week window.
What's actually been approved in HA8 lately?
Ten residential schemes in the most recent window — including a hip-to-gable roof extension with rear dormer and two front rooflights at 92 St Margarets Road, a single-storey rear extension at 121A Fairfield Crescent, and another hip-to-gable with rear dormer at 58 Harrowes Meade.
What's the best project for a 1930s Edgware semi?
The data keeps answering: a hip-to-gable loft with rear dormer upstairs, a single-storey rear downstairs — separately or as a phased pair. On Edgware's hipped-roof stock they add the most space for the least planning friction, and they're the schemes passing street after street.
Will I need party wall agreements with my neighbours?
On a semi, almost certainly — works on or near the shared wall engage the Party Wall Act. Budget £1,000–£2,500 per affected neighbour if surveyors get involved, talk to the neighbours early, and we'll handle the formal notices as part of the project.
Nearby areas we cover
Ready to see what's possible on your street?
Free site visit anywhere in Edgware, honest feasibility advice and a fixed, itemised price — design, planning and build handled end to end.
Or call us — 020 3051 9430