What you could build at EN5 3JJ: 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 Totteridge & Barnet Gate, Barnet.
19extensions seen within 600 m in the last 10 years
0loft conversions within 600 m in the last 10 years
123extensions 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 (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 Totteridge & Barnet Gate.
Move to a home 20 m² bigger (about £1,270,000)
Stamp duty on the new home
£70,750
Estate agent on yours 1.2% + VAT
£16,056
Solicitors, buying and selling
£3,000
Survey
£600
Removals
£1,500
Money gone
£91,906
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
−£93,000
Money gone
−£35,500
On these figures, extending loses about £127,406 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.
Loft or dormer
Approved
Sept 2026
25/3540/HSE
Edera, Hendon Wood Lane, Nw7 4hs
Side return or wrap-around
Approved
Jan 2025
24/5156/HSE
22, Highmead, Rowley Green Road, En5 3hj
Porch or front extension
Refused
Jan 2025
24/4506/HSE
8, Barnet Gate Lane, En5 2ab
Loft or dormer
Approved
Dec 2024
24/4208/HSE
61, Hendon Wood Lane, Nw7 4ht
Loft or dormer
Refused
Aug 2024
24/2299/HSE
252, 5, Mountview Cottages, Barnet Road, En5 3lb
Other householder work
Approved
Jul 2024
24/1807/HSE
32, Tabora Lodge, Rowley Green Road, En5 3hj
Two-storey extension
Approved
May 2024
24/0487/HSE
61, Hendon Wood Lane, Nw7 4ht
Loft or dormer
Approved
Apr 2024
24/0813/HSE
3, Winifred Close, En5 3lr
Loft or dormer
Approved
Apr 2024
24/0607/HSE
3, Hendon Wood Lane, Nw7 4hs
Windows, doors or cladding
Approved
Mar 2024
24/0329/HSE
169, Brambles, Barnet Road, En5 3jz
Loft or dormer
Approved
May 2024
23/4782/HSE
Woodview Lodge, Hendon Wood Lane, Nw7 4hs
Loft or dormer
Approved
Mar 2024
23/4813/HSE
7, Mulberry Villa, Hendon Wood Lane, Nw7 4hs
Porch or front extension
Approved
Nov 2023
23/4108/HSE
1, Kates Close, En5 3nb
Loft or dormer
Approved
Nov 2023
23/3176/HSE
Woodview Lodge, Hendon Wood Lane, Nw7 4hs
Loft or dormer
Refused
Oct 2023
23/0818/HSE
173, Thornacre Lodge, Barnet Road, En5 3jz
Rear extension
Approved
Jun 2023
23/1732/HSE
2, Sitwell House, Hayden Close, En5 3lt
Rear extension
Approved
Oct 2023
23/0734/HSE
Ashley Pines, Barnet Gate Lane, En5 2aa
Other householder work
Approved
Apr 2023
23/0373/HSE
83, Fallowfield, Hendon Wood Lane, Nw7 4ht
Other householder work
Approved
Apr 2023
23/0189/HSE
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.
Garage conversion or garage
70% (10)
94% (157)
88%
8 weeks
Basement
–
82% (92)
83%
8 weeks
Porch or front extension
71% (7)
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.