What you could build at N3 2RE: 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 Fallow Corner, Barnet.
93extensions seen within 600 m in the last 10 years
1loft conversions within 600 m in the last 10 years
92.1extensions 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.
Not in a conservation area (from council registers).
Article 4 direction (Article 4 Small Houses in Multiple Occupation (HMO) Area 1): 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 Fallow Corner.
Move to a home 20 m² bigger (about £796,000)
Stamp duty on the new home
£29,800
Estate agent on yours 1.2% + VAT
£9,504
Solicitors, buying and selling
£3,000
Survey
£600
Removals
£1,500
Money gone
£44,404
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
−£81,600
Money gone
−£24,100
On these figures, extending loses about £68,504 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.
54, Manor View, N3 2sr
Rear extension
Refused
Aug 2026
26/2637/PNH
51, Glebe Road, N3 2ba
Loft or dormer
Approved
Jun 2026
26/1440/HSE
38, Squires Lane, N3 2at
Rear extension
Approved
Jun 2026
26/1298/HSE
2, Cromwell Road, N3 2et
Rear extension
Approved
Apr 2026
26/1107/PNH
16, Park Avenue, N3 2ej
Rear extension
Approved
May 2026
26/0900/HSE
2, Queens Road, N3 2ag
Rear extension
Approved
Apr 2026
26/0755/HSE
2, Queens Road, N3 2ag
Rear extension
Not needed / lawful
Mar 2026
26/0679/PNH
42, Squires Lane, N3 2at
Rear extension
Refused
Mar 2026
26/0412/PNH
117, Etchingham Park Road, N3 2ee
Loft or dormer
Approved
Mar 2026
26/0132/HSE
18, Squires Lane, N3 2at
Loft or dormer
Withdrawn
Feb 2026
26/0094/HSE
9, Brighton Road, N2 8ju
Loft or dormer
Approved
Mar 2026
26/0072/HSE
34, Clifton Road, N3 2ar
Side return or wrap-around
Approved
Mar 2026
26/0076/HSE
16, Squires Lane, N3 2at
Loft or dormer
Withdrawn
Feb 2026
26/0041/HSE
42, Squires Lane, N3 2at
Loft or dormer
Approved
Mar 2026
25/4721/HSE
297, Long Lane, N2 8jw
Rear extension
Approved
Jan 2026
25/4132/HSE
16, Oakfield Road, N3 2ht
Rear extension
Not needed / lawful
Nov 2025
25/4019/PNH
43, Briarfield Avenue, N3 2lg
Loft or dormer
Approved
Nov 2025
25/3946/HSE
9, Cadogan Gardens, N3 2hn
Loft or dormer
Approved
Nov 2025
25/3848/HSE
155, Station Road, N3 2sp
Loft or dormer
Refused
Oct 2025
25/3586/HSE
187, Long Lane, N3 2re
Rear extension
Approved
Nov 2025
25/3434/HSE
24, Park Avenue, N3 2ej
Outbuilding or garden room
Withdrawn
Sept 2025
25/3147/HSE
27, Dickens Avenue, N3 2al
Rear extension
Approved
Sept 2025
25/2930/HSE
1, Rosemary Avenue, N3 2qp
Loft or dormer
Approved
Jul 2025
25/2642/HSE
27, Dickens Avenue, N3 2al
Rear extension
Not needed / lawful
Aug 2025
25/2678/PNH
8, Montpelier Road, N3 2er
Loft or dormer
Approved
Aug 2025
25/2532/HSE
26, Cadogan Gardens, N3 2hn
Loft or dormer
Approved
Jul 2025
25/2360/HSE
1, Rosemary Avenue, N3 2qp
Rear extension
Refused
Jun 2025
25/2018/PNH
9, Lewis Gardens, N2 9an
Loft or dormer
Approved
Jun 2025
25/1805/HSE
23, Manor View, N3 2st
Rear extension
Approved
Jun 2025
25/1752/HSE
117, Long Lane, N3 2hy
Side return or wrap-around
Approved
May 2025
25/1401/HSE
74, Brendon Grove, N2 8jz
Rear extension
Approved
Apr 2025
25/0860/HSE
15, Dickens Avenue, N3 2al
Rear extension
Approved
Apr 2025
25/0811/HSE
20, Manor Cottages Approach, N2 8jr
Two-storey extension
Approved
May 2025
25/0688/HSE
15, Dickens Avenue, N3 2al
Rear extension
Withdrawn
Feb 2025
25/0471/PNH
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.
–
94% (157)
88%
8 weeks
Basement
–
82% (92)
83%
8 weeks
Porch or front extension
–
86% (131)
81%
8 weeks
Share of decided applications approved since 2023 (number decided in brackets). Withdrawn applications aren't counted; many are withdrawn when refusal looks likely.