What you could build at N9 9AZ: 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 Haslebury South, Enfield.
50extensions seen within 600 m in the last 10 years
6loft conversions within 600 m in the last 10 years
74extensions 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 (126,300 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 Haslebury South.
Move to a home 20 m² bigger (about £556,000)
Stamp duty on the new home
£17,800
Estate agent on yours 1.2% + VAT
£6,480
Solicitors, buying and selling
£3,000
Survey
£600
Removals
£1,500
Money gone
£29,380
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
−£63,600
Money gone
−£6,100
On these figures, extending loses about £35,480 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.
4, Sunnyside Road North, N9 9sw
Rear extension
Not needed / lawful
Jul 2026
26/02135/PRH
2, Hawthorne Way, N9 9rd
Two-storey extension
Approved
Jun 2026
26/01550/HOU
2a, Lion Road, N9 9dw
Other householder work
Approved
Jun 2026
26/01412/PMA
18, Hawthorne Way, N9 9rd
Side return or wrap-around
Approved
Jun 2026
26/01400/HOU
14, Bedevere Road, N9 9yt
Loft or dormer
Refused
May 2026
26/01401/HOU
18, Hawthorne Way, N9 9rd
Rear extension
Not needed / lawful
Apr 2026
26/00867/PRH
1, Sunnyside Road East, N9 9sp
Rear extension
Not needed / lawful
Apr 2026
26/00859/PRH
113, Victoria Road, N9 9bd
Rear extension
Not needed / lawful
Apr 2026
26/00825/PRH
1, 5, Hostel, Church Street, N9 9dr
Other householder work
Not needed / lawful
Apr 2026
26/00668/PAT
25, Hyde Way, N9 9ru
Rear extension
Approved
Mar 2026
26/00130/HOU
20, Winchester Road, N9 9eb
Rear extension
Not needed / lawful
Jan 2026
25/04183/PRH
54, Dunholme Road, N9 9qn
Other householder work
Approved
Jan 2026
25/04090/RE4
73, Dunholme Road, N9 9qs
Rear extension
Not needed / lawful
Dec 2025
25/04032/PRH
149, Felixstowe Road, N9 0dt
Loft or dormer
Refused
Dec 2025
25/03442/HOU
1, Sunnyside Road East, N9 9sp
Rear extension
Refused
Dec 2025
25/03650/PRH
32, Chalfont Green, N9 9rf
Other householder work
Approved
Nov 2025
25/03569/RE4
36, Park Lane, N9 9bg
Other householder work
Approved
Nov 2025
25/03570/RE4
2, Hawthorne Way, N9 9rd
Rear extension
Approved
Nov 2025
25/03518/PRH
28, South Eastern Avenue, N9 9ns
Windows, doors or cladding
Approved
Nov 2025
25/03355/RE4
1, Chalfont Green, N9 9rh
Other householder work
Approved
Nov 2025
25/03350/RE4
19, Sweet Briar Green, N9 9nj
Other householder work
Approved
Nov 2025
25/03357/RE4
21, Sweet Briar Green, N9 9nj
Other householder work
Approved
Nov 2025
25/03358/RE4
52, Park Lane, N9 9bg
Other householder work
Approved
Oct 2025
25/03224/RE4
19, Northern Avenue, N9 9ql
Other householder work
Approved
Oct 2025
25/03220/RE4
11, Northern Avenue, N9 9ql
Other householder work
Approved
Oct 2025
25/03221/RE4
8, Northern Avenue, N9 9qj
Other householder work
Approved
Oct 2025
25/03222/RE4
8, Sweet Briar Grove, N9 9nq
Other householder work
Approved
Oct 2025
25/03223/RE4
58, Park Lane, N9 9bg
Other householder work
Approved
Oct 2025
25/03226/RE4
49, Church Lane, N9 9pz
Loft or dormer
Approved
Oct 2025
25/02708/HOU
45, South Eastern Avenue, N9 9lx
Other householder work
Approved
Oct 2025
25/03022/RE4
59, South Eastern Avenue, N9 9lx
Other householder work
Approved
Oct 2025
25/03023/RE4
181, Victoria Road, N9 9ax
Other householder work
Approved
Oct 2025
25/02841/RE4
183, Victoria Road, N9 9ax
Other householder work
Approved
Oct 2025
25/02842/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.