What you could build at EN1 4TN: 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 Carterhatch & Forty Hall, Enfield.
46extensions seen within 600 m in the last 10 years
7loft conversions within 600 m in the last 10 years
74.8extensions 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 Carterhatch & Forty Hall.
Move to a home 20 m² bigger (about £560,000)
Stamp duty on the new home
£18,000
Estate agent on yours 1.2% + VAT
£6,480
Solicitors, buying and selling
£3,000
Survey
£600
Removals
£1,500
Money gone
£29,580
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
−£66,000
Money gone
−£8,500
On these figures, extending loses about £38,080 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.
Rear extension
Refused
Sept 2026
26/03123/PRH
48, Clay Hill, En2 9aw
Rear extension
Approved
Sept 2026
26/02907/HOU
476, Baker Street, En1 3qs
Rear extension
Refused
Aug 2026
26/02701/PRH
476, Baker Street, En1 3qs
Rear extension
Refused
Aug 2026
26/02895/PRH
258, Carterhatch Lane, En1 4bg
Other householder work
Refused
Aug 2026
26/02246/HOU
480, Baker Street, En1 3qs
Rear extension
Refused
Jul 2026
26/02364/PRH
476, Baker Street, En1 3qs
Rear extension
Refused
Jul 2026
26/02466/PRH
476, Baker Street, En1 3qs
Rear extension
Refused
Jun 2026
26/01692/PRH
480, Baker Street, En1 3qs
Rear extension
Refused
Jun 2026
26/01649/PRH
24, Orchard Crescent, En1 3ns
Rear extension
Approved
May 2026
26/00618/HOU
383, Carterhatch Lane, En1 4an
Rear extension
Not needed / lawful
Mar 2026
26/00353/PRH
26, Clay Hill, En2 9aa
Two-storey extension
Approved
Feb 2026
25/04023/HOU
266, Carterhatch Lane, En1 4bg
Rear extension
Not needed / lawful
Dec 2025
25/03967/PRH
47, Inverness Avenue, En1 3nu
Rear extension
Approved
Nov 2025
25/02581/HOU
38, Willow Road, En1 3nd
Rear extension
Not needed / lawful
Nov 2025
25/03259/PRH
23, Goat Lane, En1 4tz
Outbuilding or garden room
Approved
Nov 2025
25/03031/HOU
48, Willow Road, En1 3nd
Two-storey extension
Refused
Nov 2025
25/03056/HOU
435, Baker Street, En1 3qy
Rear extension
Approved
Oct 2025
25/03063/PRH
15, Eastbury Avenue, En1 3nj
Loft or dormer
Refused
Oct 2025
25/02767/HOU
15, Eastbury Avenue, En1 3nj
Windows, doors or cladding
Approved
Oct 2025
25/02820/HOU
39, Bridgenhall Road, En1 4az
Rear extension
Not needed / lawful
Sept 2025
25/02787/PRH
15, Eastbury Avenue, En1 3nj
Rear extension
Not needed / lawful
Sept 2025
25/02768/PRH
66, St Georges Road, En1 4tx
Rear extension
Not needed / lawful
Sept 2025
25/02733/PRH
18, Bridgenhall Road, En1 4ay
Rear extension
Approved
Oct 2025
25/02370/HOU
24, Bridgenhall Road, En1 4ay
Porch or front extension
Approved
Aug 2025
25/02382/HOU
26, Clay Hill, En2 9aa
Rear extension
Refused
Aug 2025
25/02145/HOU
435, Baker Street, En1 3qy
Rear extension
Refused
Aug 2025
25/02171/HOU
43, Goat Lane, En1 4ua
Side extension
Approved
Jul 2025
25/01822/HOU
437, Baker Street, En1 3qy
Rear extension
Not needed / lawful
May 2025
25/01040/PRH
7, Eastbury Avenue, En1 3nj
Side extension
Approved
Mar 2025
25/00509/HOU
40, Willow Road, En1 3nd
Rear extension
Approved
Feb 2025
25/00181/PRH
Edelsten House, Forty Hill, En2 9eu
Outbuilding or garden room
Approved
Mar 2025
25/00046/HOU
44, Carisbrook Close, En1 3nb
Rear extension
Not needed / lawful
Feb 2025
25/00029/PRH
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.