What you could build at NW11 9RH: 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 Golders Green North, Barnet.
110extensions seen within 600 m in the last 10 years
15loft conversions within 600 m in the last 10 years
75.3extensions 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 (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 Golders Green North.
Move to a home 20 m² bigger (about £1,314,000)
Stamp duty on the new home
£75,150
Estate agent on yours 1.2% + VAT
£16,704
Solicitors, buying and selling
£3,000
Survey
£600
Removals
£1,500
Money gone
£96,954
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
−£92,400
Money gone
−£34,900
On these figures, extending loses about £131,854 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.
19, The Grove, Nw11 9sj
Rear extension
Not needed / lawful
Oct 2026
26/3271/PNH
36, Western Avenue, Nw11 9hj
Loft or dormer
Under consideration
–
26/2957/HSE
25, Prayle Grove, Nw2 1ba
Two-storey extension
Approved
Oct 2026
26/2915/HSE
49, Wessex Gardens, Nw11 9rs
Loft or dormer
Refused
Sept 2026
26/2885/HSE
57, Woodville Road, Nw11 9ts
Rear extension
Refused
Sept 2026
26/2832/PNH
47, Elmcroft Crescent, Nw11 9ta
Rear extension
Refused
Aug 2026
26/2545/PNH
1, Woodville Gardens, Nw11 9ed
Loft or dormer
Approved
Sept 2026
26/2624/HSE
61, Basing Hill, Nw11 8tg
Two-storey extension
Refused
Aug 2026
26/2404/HSE
41, Sneath Avenue, Nw11 9aj
Rear extension
Not needed / lawful
Jul 2026
26/2353/PNH
43, Sneath Avenue, Nw11 9aj
Rear extension
Not needed / lawful
Jul 2026
26/2354/PNH
199, Hendon Way, Nw2 1jj
Loft or dormer
Approved
Aug 2026
26/2279/HSE
72, The Ridgeway, Nw11 8pg
Rear extension
Approved
Aug 2026
26/2307/HSE
7, Highfield Gardens, Nw11 9hd
Loft or dormer
Approved
Jul 2026
26/2098/HSE
24, Western Avenue, Nw11 9hj
Two-storey extension
Approved
Aug 2026
26/1996/HSE
28, Wallcote Avenue, Nw2 1au
Two-storey extension
Approved
Jul 2026
26/1848/HSE
17, Western Avenue, Nw11 9he
Loft or dormer
Approved
Jul 2026
26/1632/HSE
56, Basing Hill, Nw11 8th
Loft or dormer
Approved
Jun 2026
26/1642/HSE
45, The Ridgeway, Nw11 8qp
Loft or dormer
Approved
Jun 2026
26/1603/HSE
24, Western Avenue, Nw11 9hj
Rear extension
Not needed / lawful
May 2026
26/1425/PNH
24, Heathfield Gardens, Nw11 9hx
Two-storey extension
Approved
Jun 2026
26/1288/HSE
30, Powis Gardens, Nw11 8hh
Loft or dormer
Approved
May 2026
26/1068/HSE
61, Basing Hill, Nw11 8tg
Rear extension
Not needed / lawful
Apr 2026
26/0991/PNH
48, Highfield Avenue, Nw11 9ud
Two-storey extension
Approved
May 2026
26/0856/HSE
24, Western Avenue, Nw11 9hj
Two-storey extension
Refused
Mar 2026
26/0257/HSE
24, Heathfield Gardens, Nw11 9hx
Rear extension
Not needed / lawful
Mar 2026
26/0345/PNH
23, Armitage Road, Nw11 8qt
Loft or dormer
Approved
Mar 2026
26/0228/HSE
48, Highfield Avenue, Nw11 9ud
Rear extension
Not needed / lawful
Feb 2026
26/0045/PNH
Olympia House, Armitage Road, Nw11 8rq
Other householder work
Approved
Feb 2026
25/5162/PNV
48, Golders Gardens, Nw11 9bu
Loft or dormer
Refused
Feb 2026
25/5168/HSE
55, Armitage Road, Nw11 8qt
Loft or dormer
Approved
Feb 2026
25/5128/HSE
24, Heathfield Gardens, Nw11 9hx
Rear extension
Refused
Jan 2026
25/5094/PNH
24, Heathfield Gardens, Nw11 9hx
Two-storey extension
Withdrawn
Feb 2026
25/5095/HSE
20, The Grove, Nw11 9sh
Loft or dormer
Approved
Feb 2026
25/4967/HSE
24, Western Avenue, Nw11 9hj
Rear extension
Not needed / lawful
Jan 2026
25/4897/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
73% (11)
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.