What you could build at N21 1TW: 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 Oakwood Park & Highlands, Enfield.
64extensions seen within 600 m in the last 10 years
3loft conversions within 600 m in the last 10 years
69.5extensions 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
Mostly flats at this postcode. Flats have no permitted development rights, so almost any extension or loft conversion needs planning permission, and the freeholder's consent under the lease.
In the HIGHLANDS conservation area: permitted development is narrower (for example no side extensions or roof cladding), and demolition and works to trees need consent.
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 Oakwood Park & Highlands.
Move to a home 20 m² bigger (about £791,000)
Stamp duty on the new home
£29,550
Estate agent on yours 1.2% + VAT
£9,504
Solicitors, buying and selling
£3,000
Survey
£600
Removals
£1,500
Money gone
£44,154
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
−£78,600
Money gone
−£21,100
On these figures, extending loses about £65,254 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.
41, The Birches, N21 1nj
Rear extension
Approved
Jun 2026
26/01663/PRH
9, Chadwick Avenue, N21 1st
Rear extension
Refused
May 2026
26/01432/PRH
27, The Birches, N21 1nj
Two-storey extension
Approved
May 2026
26/00952/HOU
166, Green Dragon Lane, N21 1ep
Side extension
Refused
May 2026
26/00965/HOU
41, Eversley Park Road, N21 1jj
Loft or dormer
Approved
Mar 2026
26/00451/HOU
41, Eversley Park Road, N21 1jj
Rear extension
Not needed / lawful
Mar 2026
26/00452/PRH
137, Prince George Avenue, N14 4td
Rear extension
Approved
Jan 2026
25/04077/HOU
137, Green Dragon Lane, N21 1eu
Two-storey extension
Approved
Jan 2026
25/03790/HOU
27, Hanbury Drive, N21 1sz
Rear extension
Approved
Jan 2026
25/03787/HOU
140, Prince George Avenue, N14 4ta
Two-storey extension
Approved
Jan 2026
25/03542/HOU
73, Uplands Way, N21 1du
Other householder work
Approved
Dec 2025
25/03755/VAR
156, Green Dragon Lane, N21 1et
Other householder work
Approved
Dec 2025
25/03682/HOU
35, Oakwood Crescent, N21 1nx
Porch or front extension
Approved
Dec 2025
25/03390/HOU
8, Maxim Road, N21 1ex
Porch or front extension
Approved
Nov 2025
25/03550/HOU
95, Vera Avenue, N21 1rn
Loft or dormer
Approved
Dec 2025
25/03544/HOU
1, Maplin Close, N21 1nb
Other householder work
Refused
Nov 2025
25/03175/PRA
142, Green Dragon Lane, N21 1et
Rear extension
Approved
Oct 2025
25/02881/HOU
157, Prince George Avenue, N14 4td
Rear extension
Approved
Oct 2025
25/02838/HOU
156, Green Dragon Lane, N21 1et
Porch or front extension
Approved
Sept 2025
25/02466/HOU
156, Green Dragon Lane, N21 1et
Loft or dormer
Approved
Sept 2025
25/02468/HOU
156, Green Dragon Lane, N21 1et
Rear extension
Approved
Sept 2025
25/02467/HOU
40, Eversley Crescent, N21 1eu
Porch or front extension
Approved
Sept 2025
25/02324/HOU
153, Lonsdale Drive, En2 7nb
Two-storey extension
Approved
Aug 2025
25/02261/HOU
48, Cranleigh Gardens, N21 1ds
Rear extension
Approved
Aug 2025
25/01959/HOU
166, Green Dragon Lane, N21 1ep
Side extension
Refused
Oct 2025
25/01901/HOU
168, South Lodge Drive, N14 4xl
Loft or dormer
Approved
Jul 2025
25/01242/HOU
11, Holly Hill, N21 1nn
Rear extension
Approved
Jun 2025
25/01369/HOU
43, Eversley Crescent, N21 1el
Two-storey extension
Approved
Jun 2025
25/01405/HOU
3, Macleod Road, N21 1sw
Rear extension
Not needed / lawful
May 2025
25/01421/PRH
157, Prince George Avenue, N14 4td
Rear extension
Not needed / lawful
May 2025
25/01212/PRH
130, Lonsdale Drive, En2 7nd
Rear extension
Approved
May 2025
25/01080/HOU
19, Hanbury Drive, N21 1sz
Rear extension
Approved
May 2025
24/04402/HOU
9, Laidlaw Drive, N21 1ss
Loft or dormer
Approved
May 2025
25/00884/HOU
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.
100% (5)
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.