What you could build at NW11 0NT: 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 Temple Fortune, Barnet.
100extensions seen within 600 m in the last 10 years
11loft conversions within 600 m in the last 10 years
88.4extensions 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 Temple Fortune.
Move to a home 20 m² bigger (about £1,213,000)
Stamp duty on the new home
£65,050
Estate agent on yours 1.2% + VAT
£14,760
Solicitors, buying and selling
£3,000
Survey
£600
Removals
£1,500
Money gone
£84,910
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
−£112,800
Money gone
−£55,300
On these figures, extending loses about £140,210 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.
70, Hampstead Way, Nw11 7xx
Windows, doors or cladding
Under consideration
–
26/2870/HSE
17, Hampstead Gardens, Nw11 7eu
Rear extension
Refused
Sept 2026
26/3064/PNH
14, Hampstead Gardens, Nw11 7eu
Loft or dormer
Under consideration
–
26/3024/HSE
5, Hill Close, Nw11 7jp
Other householder work
Approved
Sept 2026
26/2954/HSE
14, Cranbourne Gardens, Nw11 0hp
Rear extension
Not needed / lawful
Sept 2026
26/2943/PNH
3, St Georges Close, Nw11 0lt
Loft or dormer
Approved
Oct 2026
26/2899/HSE
22, Highcroft Gardens, Nw11 0lx
Rear extension
Refused
Aug 2026
26/2553/PNH
16, Corringham Road, Nw11 7bt
Loft or dormer
Under consideration
–
26/2355/HSE
14, Cranbourne Gardens, Nw11 0hp
Rear extension
Refused
Aug 2026
26/2471/PNH
24, Alba Gardens, Nw11 9nr
Rear extension
Not needed / lawful
Jul 2026
26/2442/PNH
10, Eastville Avenue, Nw11 0hd
Two-storey extension
Approved
Aug 2026
26/2331/HSE
8, Temple Fortune Hill, Nw11 7xn
Windows, doors or cladding
Approved
Sept 2026
26/2333/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
148, Hampstead Way, Nw11 7xh
Windows, doors or cladding
Approved
Sept 2026
26/1933/HSE
50, Brookside Road, Nw11 9ne
Rear extension
Refused
Jul 2026
26/2153/PNH
73, Willifield Way, Nw11 6yl
Loft or dormer
Approved
Jul 2026
26/2106/HSE
109, Wentworth Road, Nw11 0rh
Two-storey extension
Refused
Jul 2026
26/1853/HSE
183, Hampstead Way, Nw11 7yb
Loft or dormer
Refused
Jul 2026
26/1784/HSE
2, Elmcroft Avenue, Nw11 0rr
Loft or dormer
Approved
Jul 2026
26/1705/HSE
29, Leeside Crescent, Nw11 0da
Loft or dormer
Approved
Jun 2026
26/1567/HSE
22, Highcroft Gardens, Nw11 0lx
Rear extension
Refused
Jun 2026
26/1479/HSE
3, St Georges Close, Nw11 0lt
Rear extension
Approved
Jun 2026
26/1437/HSE
14, Cranbourne Gardens, Nw11 0hp
Two-storey extension
Approved
Jun 2026
26/1451/HSE
33, Russell Gardens, Nw11 9nj
Garage conversion or garage
Approved
May 2026
26/1199/HSE
33, Russell Gardens, Nw11 9nj
Rear extension
Approved
May 2026
26/1200/HSE
3, St Georges Close, Nw11 0lt
Two-storey extension
Refused
May 2026
26/1078/HSE
3, St Georges Close, Nw11 0lt
Loft or dormer
Approved
Jun 2026
26/1079/HSE
29, Leeside Crescent, Nw11 0da
Rear extension
Not needed / lawful
Apr 2026
26/0982/PNH
109, Wentworth Road, Nw11 0rh
Two-storey extension
Refused
May 2026
26/0795/HSE
3, Grosvenor Gardens, Nw11 0hh
Loft or dormer
Approved
Apr 2026
26/0739/HSE
41, Temple Fortune Hill, Nw11 7xp
Other householder work
Approved
May 2026
26/0414/HSE
3, Grosvenor Gardens, Nw11 0hh
Rear extension
Not needed / lawful
Jan 2026
25/5051/PNH
57, Templars Avenue, Nw11 0nu
Rear extension
Refused
Jan 2026
25/5121/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.
100% (10)
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.