What you could build at EN5 4DS: 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 High Barnet & Hadley, Barnet.
75extensions seen within 600 m in the last 10 years
4loft conversions within 600 m in the last 10 years
91.8extensions 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 (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 High Barnet & Hadley.
Move to a home 20 m² bigger (about £836,000)
Stamp duty on the new home
£31,800
Estate agent on yours 1.2% + VAT
£10,152
Solicitors, buying and selling
£3,000
Survey
£600
Removals
£1,500
Money gone
£47,052
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
−£78,600
Money gone
−£21,100
On these figures, extending loses about £68,152 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.
26/2837/HSE
Heron Croft, Cavendish Road, En5 4ed
Loft or dormer
Refused
Sept 2026
26/2727/HSE
3, Alston Road, En5 4et
Loft or dormer
Approved
Sept 2026
26/2743/HSE
34, Byng Road, En5 4nr
Rear extension
Refused
Aug 2026
26/2631/PNH
10, Wentworth Road, En5 4nt
Outbuilding or garden room
Approved
Sept 2026
26/2484/HSE
8, Queens Road, En5 4dg
Loft or dormer
Approved
Jul 2026
26/2163/HSE
61, Sebright Road, En5 4hp
Loft or dormer
Approved
Jul 2026
26/2010/HSE
39, Old Fold View, En5 4ea
Two-storey extension
Refused
Aug 2026
26/1382/HSE
8, Queens Road, En5 4dg
Loft or dormer
Refused
Jun 2026
26/1612/HSE
17, Sebright Road, En5 4hr
Rear extension
Approved
May 2026
26/1292/HSE
27, Elmbank Avenue, En5 3du
Porch or front extension
Approved
May 2026
26/1210/HSE
56, Old Fold View, En5 4eb
Side extension
Approved
Apr 2026
26/0792/HSE
43, Granville Road, En5 4ds
Loft or dormer
Approved
Apr 2026
26/0732/HSE
137, Wood Street, En5 4bx
Loft or dormer
Refused
Mar 2026
26/0585/HSE
137, Wood Street, En5 4bx
Two-storey extension
Approved
Mar 2026
26/0586/HSE
27, Elmbank Avenue, En5 3du
Porch or front extension
Refused
Mar 2026
26/0246/HSE
6, Jennings Way, En5 4eq
Loft or dormer
Approved
Feb 2026
25/5078/HSE
Heron Croft, Cavendish Road, En5 4ed
Loft or dormer
Approved
Feb 2026
25/5085/HSE
12, Queens Road, En5 4dg
Loft or dormer
Withdrawn
Jan 2026
25/4896/HSE
15, Kings Road, En5 4ef
Rear extension
Approved
Jan 2026
25/4845/HSE
17, Byng Road, En5 4nw
Rear extension
Refused
Feb 2026
25/4700/HSE
31, Byng Road, En5 4nw
Loft or dormer
Refused
Jan 2026
25/4459/HSE
6, Barnet Road, En5 3ep
Outbuilding or garden room
Refused
Dec 2025
25/4338/HSE
15, Galley Lane, En5 4ar
Loft or dormer
Approved
Nov 2025
25/4056/HSE
17, Byng Road, En5 4nw
Rear extension
Not needed / lawful
Nov 2025
25/3975/PNH
6, Lexington Way, En5 2sn
Loft or dormer
Withdrawn
Oct 2025
25/3724/HSE
31, Byng Road, En5 4nw
Rear extension
Not needed / lawful
Oct 2025
25/3781/PNH
120, Wood Street, En5 4da
Rear extension
Approved
Oct 2025
25/3622/HSE
Opposite The Arkley Public House, Wood Street, En5 4db
Other householder work
Refused
Sept 2025
25/3448/PNT
45, The Croft, En5 2tn
Side extension
Approved
Sept 2025
25/3063/HSE
6, Kerri Close, En5 3er
Loft or dormer
Approved
Sept 2025
25/3112/HSE
53, Old Fold View, En5 4ea
Rear extension
Withdrawn
Jul 2025
25/3006/PNH
12, Grimsdyke Crescent, En5 4ag
Loft or dormer
Approved
Dec 2025
25/3025/HSE
15, Galley Lane, En5 4ar
Porch or front extension
Withdrawn
Aug 2025
25/2920/HSE
15, Galley Lane, En5 4ar
Loft or dormer
Approved
Jun 2025
25/2088/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.
88% (8)
94% (157)
88%
8 weeks
Basement
–
82% (92)
83%
8 weeks
Porch or front extension
67% (9)
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.