What you could build at N19 4EU: 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 Highcroft & Holly Park, Islington.
143extensions seen within 600 m in the last 10 years
21loft conversions within 600 m in the last 10 years
91.3extensions 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).
No Article 4 direction recorded for this postcode.
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 Highcroft & Holly Park.
Move to a home 20 m² bigger (about £702,000)
Stamp duty on the new home
£25,100
Estate agent on yours 1.2% + VAT
£7,848
Solicitors, buying and selling
£3,000
Survey
£600
Removals
£1,500
Money gone
£38,048
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
−£94,200
Money gone
−£36,700
On these figures, extending loses about £74,748 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
Apr 2026
P2026/0617/FUL
51, Landseer Road, N19 4jr
Loft or dormer
Approved
–
P2026/0589/FUL
44, Alexander Road, N19 3pq
Side return or wrap-around
Approved
May 2026
P2026/0376/FUL
14, Corbyn Street, N4 3bz
Loft or dormer
Approved
May 2026
P2026/0404/FUL
11, Ormond Road, N19 3qg
Loft or dormer
Other
Mar 2026
P2026/0234/COL
14, Corbyn Street, N4 3bz
Loft or dormer
Other
Feb 2026
P2025/2964/COL
65, Sussex Way, N7 6ru
Rear extension
Other
Jan 2026
P2025/2556/COL
52, Alexander Road, N19 3pq
Rear extension
Approved
Jan 2026
P2025/2318/FUL
55, Kingsdown Road, N19 4ld
Other householder work
Withdrawn
–
P2025/2188/FUL
21, Wedmore Gardens, N19 4dl
Loft or dormer
Approved
Oct 2025
P2025/2233/FUL
70, Kingsdown Road, N19 4lw
Porch or front extension
Refused
Sept 2025
P2025/2066/FUL
88, Corbyn Street, N4 3bz
Loft or dormer
Approved
Oct 2025
P2025/2174/FUL
15, Calverley Grove, N19 3lq
Loft or dormer
Other
Aug 2025
P2025/1775/COL
13, Grenville Road, N19 4ej
Loft or dormer
Withdrawn
Jul 2025
P2025/1424/COL
72, 72 Flat C, Hanley Road, N4 3dr
Other householder work
Approved
May 2026
P2025/1246/FUL
15, Calverley Grove, N19 3lq
Outbuilding or garden room
Other
May 2025
P2025/1092/COL
Trinder Road, N19 4qu
Loft or dormer
Refused
Feb 2024
P2023/3472/FUL
51, Lambton Road, N19 3qj
Loft or dormer
Other
Jan 2024
P2023/3470/COLP
19, Almington Street, N4 3bg
Loft or dormer
Other
Jan 2024
P2023/3478/COLP
Ground Floor Flat, Corbyn Street, N4 3bx
Loft or dormer
Refused
Feb 2024
P2023/3484/FUL
Tollington Way, N7 6rg
Loft or dormer
Other
–
P2023/2756
Kiver Road, N19 4pd
Loft or dormer
Other
–
P2023/2765
12, Kiver Road, N19 4pd
Loft or dormer
Other
Oct 2023
P2023/2765/COLP
Landseer Road, N19 4ju
Other householder work
Other
–
P2023/2741
61, Fairbridge Road, N19 3ep
Loft or dormer
Other
Oct 2023
P2023/2644/COLP
Kingsdown Road, N19 4ld
Loft or dormer
Approved
Feb 2024
P2023/1995/FUL
36, Mitford Road, N19 4hl
Rear extension
Other
Oct 2023
P2023/2629/COLP
28, Kiver Road, N19 4pd
Loft or dormer
Other
Sept 2023
P2023/2311/COLP
94, Thorpedale Road, N4 3bw
Rear extension
Other
Sept 2023
P2023/1663/COLP
9, Whewell Road, N19 4ls
Loft or dormer
Other
Jul 2023
P2023/1569/COLP
108, Thorpedale Road, N4 3bs
Loft or dormer
Other
Jul 2023
P2023/1402/COLP
21, Kingsdown Road, N19 4ld
Loft or dormer
Refused
Apr 2023
P2023/0697/COLP
12, Whewell Road, N19 4ls
Loft or dormer
Other
Mar 2023
P2023/0415/COLP
52, Kiver Road, N19 4pd
Rear extension
Approved
Mar 2023
P2023/0368/FUL
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 weeks
Basement
–
80% (10)
83%
9 weeks
Porch or front extension
–
–
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.