Area guide · EN4
House Extensions in Hadley Wood (EN4)
Planning a house extension in Hadley Wood? We design, gain planning permission and build extensions across one of North London's most sought-after enclaves. Expect a single-storey rear to build at £55,000–£115,000 — and here's the detail that surprises many residents: most of Hadley Wood is decided by Enfield Council, not Barnet. The schemes winning approval are large glazed single-storey rears, double-storey extensions and design-led reworks. A free site visit settles both questions early: what your plot can carry, and which council will judge it.
Live planning data
What Enfield Council is actually approving right now
First, the quirk worth knowing. Hadley Wood sits inside the London Borough of Enfield — despite the EN4 postcode it shares with East Barnet and New Barnet, and despite feeling like Barnet country. The borough boundary runs close to Hadley Wood's western edge, so which council decides your application depends on your exact address. We confirm it before a single line is drawn, because it changes the policies, the forms and occasionally the tactics.
The data is encouraging on both sides of the line. In a recent two-week decision window, Enfield Council approved 113 residential schemes, against Barnet's 63 in the same period. Both pipelines are moving; Enfield's is the one most Hadley Wood applications enter. And across EN4 specifically, the same window shows repeat approvals for hip-to-gable loft conversions and rear extensions — the staple schemes clearing steadily on both sides of the borough boundary.
Hadley Wood projects tend to be a class apart from the postcode's bread and butter: large single-storey rears with structural glazing, double-storey schemes and basements on substantial detached plots. At this end of the market, approvals are won on design quality — proportion, materials, landscaping — and that's precisely how we put applications together.
Source: the published planning registers of Enfield and Barnet Councils. The numbers describe the local approvals weather, not our own project list — and any individual application is decided on its own specific merits.
Local knowledge
Hadley Wood's housing stock — and what works on each
Hadley Wood is compact — a leafy grid of substantial homes around its own station — but there are distinct generations of house, each with its own playbook.
The classic avenues (the Lancaster Avenue and Crescent character). Substantial detached homes on generous plots set the tone here — and they're made for the large glazed single-storey rear (£55,000–£115,000): slim-framed sliders or full structural glazing opening the back of the house to the garden. Plots this size also carry wrap-arounds (£90,000–£180,000) without crowding the boundaries.
The period originals near the station. Hadley Wood's station opened in 1885 and the first generation of houses followed the railway. Extending these earlier homes is sensitive work — matching brickwork, roof junctions, joinery — and rewards a properly design-led application.
Replacement and modern houses. Plenty of Hadley Wood homes are later rebuilds, already generous. Here the conversation is often reconfiguration plus extension — a double-storey rear (£95,000–£210,000), a basement for leisure space, or a whole-house rework that makes the existing volume earn its keep.
The Monken Hadley edge. On the Barnet side of the boundary, the Monken Hadley conservation area sits immediately adjacent. If your address falls under Barnet and near that edge, conservation policy may shape the design. For every address, we check the council conservation maps as a first step.
Every street is different. That's the point.
We design to Hadley Wood'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 Hadley Wood in 2026
Hadley Wood build costs run 25–30% above the North London baseline — these are large houses finished to a high specification, and the glazing, stone and joinery that suit them cost real money. Realistic all-in build ranges, excluding VAT, professional fees and kitchen fit-out:
| Extension type | Typical Hadley Wood cost | On-site time | Usual planning route |
|---|---|---|---|
| Side-return extension | £45,000 – £85,000 | 2–3 months | Often permitted development |
| Single-storey rear | £55,000 – £115,000 | 3–4 months | Often permitted development |
| Kitchen extension (incl. mid-range kitchen) | £70,000 – £140,000 | 3–4 months | Often permitted development |
| Hip-to-gable loft + rear dormer | £70,000 – £115,000 | 6–10 weeks | Usually permitted development |
| Wrap-around extension | £90,000 – £180,000 | 4–6 months | Full application |
| Double-storey rear | £95,000 – £210,000 | 5–7 months | Full application |
| Garage conversion | £25,000 – £45,000 | 4–6 weeks | Usually permitted development |
Expect £3,500–£5,500 per square metre, against the wider North London range of £2,800–£4,200. A 30m² glazed rear extension typically lands well into six figures once structural glazing is specified. Our pricing works the old-fashioned way: a free site visit first, then a fixed quote itemised line by line — and that sum is what you'll actually hand over, not a starting point.
Permissions, handled
Planning permission in Hadley Wood — what you need to know
Start with the council question. EN4 splits between Enfield and Barnet, and Hadley Wood addresses mostly fall to Enfield — but we verify yours before anything else, because policy detail differs between the boroughs.
Permitted development is generous to detached houses. A detached home can push a single-storey rear extension to 4m deep without an application (semis and terraces get 3m) — and via the larger home extension scheme, prior approval with neighbour consultation unlocks 8m on detached houses and 6m on semis. Lofts carry a generous volume allowance — and EN4's recent record of repeat loft and rear-extension approvals shows these routes working. For anything built under PD, we still secure a Lawful Development Certificate, so the position is legally documented when you sell.
Bigger schemes go to full application — double-storey rears, wrap-arounds and basements — and a householder application takes roughly eight weeks to determine whichever side of the boundary you sit on. In Hadley Wood the difference between approval and refusal is usually design: schemes that respect plot rhythm, mature trees and the street's green character go through.
Party walls: detached houses mean formal awards are less common than in terraced streets — but excavation near a boundary (basements especially) can still trigger the Party Wall Act. Where surveyors are appointed, budget £1,000–£2,500 per affected neighbour. We manage the notices as standard.
How it works
How it works
- Free site visit — we tour your Hadley Wood plot, pin down whether Enfield or Barnet will decide your scheme, and talk frankly about feasibility, budget and route.
- Design & drawings — a drawing set and 3D imagery pitched at the level this market demands.
- Planning, handled — the full submission goes in under our management to Enfield or Barnet as appropriate, and we shepherd it through to the decision notice.
- Fixed-price build — built by the North London team we trust with our name, closed out with building control sign-off and an immaculate handover.
Our work
Recent work near Hadley Wood
Our builders' recent North London output features a full house transformation taking a family home from 120m² to 360m² — Hadley Wood-scale ambition — plus a 55m² garden room with kitchen and bathroom and an Edwardian conversion in Finchley. Describe the brief when we visit and we'll line up the past projects that mirror it.
Questions, answered
Hadley Wood extension FAQs
Is Hadley Wood under Barnet or Enfield Council?
Enfield, for most addresses — Hadley Wood sits within the London Borough of Enfield even though its EN4 postcode is shared with Barnet areas. The boundary runs close by, so we confirm your specific address at the outset; it determines which council's policies your application is judged against.
What should I expect to pay for a Hadley Wood extension?
Plan on £3,500–£5,500/m² — roughly 25–30% above the North London norm, reflecting the size and specification of these houses. A glazed single-storey rear typically runs £55,000–£115,000 and double-storey schemes £95,000–£210,000, excluding VAT and fees. Fixed, itemised quote after a free visit.
Can I build a big glazed rear extension without full planning permission?
Often, yes. Detached houses enjoy 4m of rear extension under permitted development, stretching to 8m with larger-home prior approval — and EN4's recent record shows rear extensions clearing repeatedly. We'd still obtain a Lawful Development Certificate so the consent is black and white.
Does the Monken Hadley conservation area affect my house?
It sits immediately adjacent on the Barnet side of the boundary, so it depends entirely on your address. If you fall within or beside it, design expectations tighten — materials and detailing in particular. We check the conservation maps for your exact plot before design begins.
Is a basement realistic in Hadley Wood?
On these plots, frequently yes — basements add leisure or guest space without changing how the house presents to the street, which planners here care about. They're full-application projects with serious engineering behind them, and party wall procedures where excavation nears a boundary.
How long will my project take?
Allow a few weeks for survey and design, around eight weeks for a council decision once submitted, and an on-site period from three or four months for a single-storey scheme to seven for a double-storey rework. We give honest programme dates with the quote.
Nearby areas we cover
Ready to see what's possible on your street?
Free site visit anywhere in Hadley Wood, honest feasibility advice and a fixed, itemised price — design, planning and build handled end to end.
Or call us — 020 3051 9430