What you could build at EN1 1JB: the planning rules at this address, what neighbours have built and how big, planning decisions nearby, rough costs and the value an extension adds, and how to get started. In Southbury West, Enfield.
87extensions seen within 600 m in the last 10 years
6loft conversions within 600 m in the last 10 years
111.3extensions per 1,000 homes in the neighbourhood (10 years)
● work seen on energy certificates · ● application approved · ● refused · ● pending or other · ● this postcode
The rules at this address
Houses usually have permitted development rights: some rear extensions (typically up to 3 m deep for a semi or terrace, 4 m detached), loft conversions within volume limits, and porches can go ahead without planning permission. Larger single-storey rear extensions (up to 6 m / 8 m) can use the “prior approval” neighbour scheme.
Not in a conservation area (from council registers).
Article 4 direction (Borough wide): some rights normally allowed have been removed here. Check what it covers with the council before relying on permitted development.
Listed buildings need listed building consent for most changes, inside and out: check the National Heritage List.
To be certain work is permitted development, apply for a lawful development certificate (about £129 for householders in England). Building regulations apply either way.
Across England and Wales, homes extended by a typical 30 m² and then resold rose about 11.1% more than similar homes nearby over the same years (124,884 resales). How extensions pay off by size, type and region.
Single-storey rear or side extension: about £2,000–£3,000 per m² (London £2,500–£4,000), plus fees and VAT
Loft conversion: about £45,000–£75,000 for a dormer; more for a mansard or hip-to-gable
Two-storey extension: about £1,800–£2,800 per m² of new floor
Garage conversion: about £15,000–£30,000
Basement: about £3,500–£5,000 per m², London mostly
Build costs are rough 2026 ranges from industry guides, not quotes. Get three quotes for your plans.
Move or improve?
The money you don't get back either way, for the same extra space in Southbury West.
Move to a home 20 m² bigger (about £574,000)
Stamp duty on the new home
£18,700
Estate agent on yours 1.2% + VAT
£6,696
Solicitors, buying and selling
£3,000
Survey
£600
Removals
£1,500
Money gone
£30,496
Extend by 20 m²
Building, plus 15% for design, planning and contingency
£57,500
Less what it adds to your home's value 60% of the local price
−£65,400
Money gone
−£7,900
On these figures, extending loses about £38,396 less. Moving also changes the area, the schools and the commute; extending means months of building work and depends on planning.
Building costs vary a lot (a single-storey rear extension is often £2,000–£3,000 per m², more in London). How much space adds depends on the home and street: what extensions added to resale prices. A guide, not advice; nothing you type leaves this page.
Getting started
Look at what neighbours did. Open applications above to see drawings that were approved on similar houses, and who designed them.
Check the route: permitted development (with a lawful development certificate), prior approval for larger rear extensions, or full householder planning permission.
Get a measured survey and a designer: an architect, an architectural technologist or a designer who handles planning drawings.
Apply (householder permission is about £258 in England; councils aim to decide within 8 weeks).
Building regulations through the council's building control or an approved inspector, and party wall notices to neighbours if you build on or near the boundary.
Choose a builder: written quotes, a contract, staged payments, and check their insurance and references.
From energy certificates: an extension where a later certificate shows more floor space, a loft conversion where roof rooms appear. Certificates come with sales, lettings and some building work, so the year is when it was first seen.
Not every extension shows here. We only see building work when a new energy certificate is lodged, which happens when a home is sold, let or newly built. A loft or extension added since then won't appear, even with planning permission and building control sign-off, because those records aren't published as open data outside London. Missing work doesn't mean missing paperwork.
78, Melbourne Way, En1 1xq
Rear extension
Refused
Aug 2026
26/02460/HOU
110, St Edmunds Road, N9 7pr
Porch or front extension
Approved
Aug 2026
26/02188/HOU
43, St Marks Road, En1 1bg
Rear extension
Approved
Sept 2026
26/02274/HOU
3, Lynmouth Avenue, En1 2lp
Rear extension
Approved
Jul 2026
26/02301/HOU
6, Woodgrange Avenue, En1 1ep
Rear extension
Approved
Aug 2026
26/01931/HOU
2, Longleat Road, En1 2qj
Windows, doors or cladding
Approved
Jul 2026
26/01970/HOU
109, Delhi Road, En1 2ly
Garage conversion or garage
Approved
Jul 2026
26/01587/HOU
51, Amberley Road, En1 2qz
Loft or dormer
Approved
Jul 2026
26/01573/HOU
22a, Mansfield Close, N9 7lu
Two-storey extension
Approved
Jul 2026
26/01869/HOU
56, Abbey Road, En1 2qn
Windows, doors or cladding
Approved
Jul 2026
26/01569/HOU
31, Woodgrange Gardens, En1 1er
Rear extension
Not needed / lawful
Jun 2026
26/02033/PRH
145, Bertram Road, En1 1lp
Rear extension
Refused
Jun 2026
26/02040/PRH
176, Lincoln Road, En1 1ln
Rear extension
Not needed / lawful
Jun 2026
26/01903/PRH
85, Dimsdale Drive, En1 1hd
Rear extension
Not needed / lawful
May 2026
26/01578/PRH
1a, Poynter Road, En1 1dn
Other householder work
Approved
Jun 2026
26/01471/PMA
83, Trinity Avenue, En1 1ht
Two-storey extension
Refused
Jun 2026
26/01136/HOU
79, Lynmouth Avenue, En1 2ls
Rear extension
Not needed / lawful
May 2026
26/01333/PRH
173, Galliard Road, N9 7ng
Two-storey extension
Approved
May 2026
26/01106/HOU
109, Dimsdale Drive, En1 1hd
Rear extension
Not needed / lawful
Apr 2026
26/00810/PRH
173, Galliard Road, N9 7ng
Two-storey extension
Refused
Feb 2026
25/04332/HOU
32, Hazelwood Road, En1 1jq
Rear extension
Not needed / lawful
Jan 2026
25/04389/PRH
22a, Mansfield Close, N9 7lu
Rear extension
Approved
Jan 2026
25/03562/HOU
4, Park Avenue, En1 2hp
Rear extension
Not needed / lawful
Nov 2025
25/03586/PRH
5, Ladbroke Road, En1 1hy
Rear extension
Not needed / lawful
Nov 2025
25/03555/PRH
97, Wellington Road, En1 2pw
Loft or dormer
Approved
Dec 2025
25/03418/HOU
13, Third Avenue, En1 1bu
Two-storey extension
Approved
Nov 2025
25/03344/RE4
35, Third Avenue, En1 1bu
Two-storey extension
Approved
Nov 2025
25/03345/RE4
49, Third Avenue, En1 1bu
Windows, doors or cladding
Approved
Nov 2025
25/03347/RE4
55, Third Avenue, En1 1bu
Windows, doors or cladding
Approved
Nov 2025
25/03348/RE4
18, Orchard Terrace, Great Cambridge Road, En1 1el
Other householder work
Approved
Nov 2025
25/03351/RE4
6, Mansfield Close, N9 7lu
Windows, doors or cladding
Approved
Nov 2025
25/03353/RE4
46, Third Avenue, En1 1bx
Two-storey extension
Approved
Nov 2025
25/03354/RE4
103, Galliard Road, N9 7pd
Windows, doors or cladding
Approved
Nov 2025
25/03356/RE4
Householder applications validated since 2023 within 600 m. The council's page has the drawings, the decision notice and who the agent or architect was. Hover a row for the description. Source: GLA Planning London Datahub.
–
85% (116)
88%
7 weeks
Basement
–
53% (17)
83%
8 weeks
Porch or front extension
–
88% (74)
81%
7 weeks
Share of decided applications approved since 2023 (number decided in brackets). Withdrawn applications aren't counted; many are withdrawn when refusal looks likely.