What you could build at SE25 6RN: 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 Thornton Heath North East, Croydon.
114extensions seen within 600 m in the last 10 years
11loft conversions within 600 m in the last 10 years
104.8extensions 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).
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 (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 Thornton Heath North East.
Move to a home 20 m² bigger (about £586,000)
Stamp duty on the new home
£19,300
Estate agent on yours 1.2% + VAT
£6,912
Solicitors, buying and selling
£3,000
Survey
£600
Removals
£1,500
Money gone
£31,312
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
−£63,600
Money gone
−£6,100
On these figures, extending loses about £37,412 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.
Rear extension
Approved
Aug 2026
26/02075/GPDO
52, Wharncliffe Gardens, Se25 6dq
Loft or dormer
Under consideration
–
26/01923/HSE
136, Clifton Road, Se25 6qa
Loft or dormer
Approved
Aug 2026
26/01820/HSE
33, Buller Road, Cr7 8qx
Rear extension
Approved
Sept 2026
26/01377/HSE
258, Whitehorse Lane, Se25 6ur
Rear extension
Approved
Jul 2026
26/01539/HSE
39b, Grange Park Road, Cr7 8qe
Two-storey extension
Refused
Jun 2026
26/00942/HSE
61, Falkland Park Avenue, Se25 6sq
Rear extension
Approved
Jun 2026
26/01093/HSE
33, Mersham Road, Cr7 8ns
Side extension
Approved
May 2026
26/00504/HSE
14, Elm Park Road, Se25 6ua
Rear extension
Approved
Apr 2026
26/00617/HSE
58, Dixon Road, Se25 6ue
Loft or dormer
Approved
May 2026
26/00538/HSE
25, Grange Gardens, Se25 6dl
Rear extension
Approved
Mar 2026
26/00170/HSE
258, Whitehorse Lane, Se25 6ur
Rear extension
Refused
Mar 2026
25/04078/HSE
24, Wharncliffe Gardens, Se25 6dq
Loft or dormer
Approved
Mar 2026
25/02643/HSE
102, Woodville Road, Cr7 8lj
Rear extension
Approved
Jan 2026
25/04041/GPDO
11, Hunter Road, Cr7 8qj
Rear extension
Approved
Dec 2025
25/03633/GPDO
17, Milner Road, Cr7 8jq
Other householder work
Under consideration
–
25/03323/HSE
165, South Norwood Hill, Se25 6de
Loft or dormer
Approved
Feb 2026
25/03386/HSE
19, Annsworthy Crescent, Grange Road, Se25 6tf
Two-storey extension
Approved
Apr 2026
25/03328/HSE
38, Ladbrook Road, Se25 6qd
Rear extension
Approved
Nov 2025
25/03086/GPDO
136, Clifton Road, Se25 6qa
Two-storey extension
Refused
Nov 2025
25/02659/HSE
24, Rothesay Road, Se25 6ny
Rear extension
Approved
Sept 2025
25/02609/GPDO
25, Grange Avenue, Se25 6dw
Rear extension
Approved
Oct 2025
25/02447/HSE
262, Whitehorse Lane, Se25 6uw
Outbuilding or garden room
Approved
Sept 2025
25/02292/HSE
79, South Norwood Hill, Se25 6by
Other householder work
Refused
Jul 2025
25/01653/HSE
1, Wharncliffe Gardens, Se25 6dg
Loft or dormer
Approved
Jul 2025
25/01676/HSE
246, South Norwood Hill, Se25 6ba
Rear extension
Approved
Jun 2025
25/00806/HSE
81, Dixon Road, Se25 6ue
Side extension
Approved
May 2025
25/00798/HSE
117, Whitehorse Lane, Se25 6ra
Side return or wrap-around
Approved
Jun 2025
25/00813/HSE
129, Whitehorse Lane, Se25 6rb
Other householder work
Approved
May 2025
25/00176/HSE
1, Wharncliffe Gardens, Se25 6dg
Loft or dormer
Refused
Apr 2025
25/00736/HSE
28, Holmewood Road, Se25 6uy
Side return or wrap-around
Approved
Apr 2025
25/00686/HSE
238, Holmesdale Road, Se25 6pt
Rear extension
Approved
Apr 2025
25/00615/GPDO
26, Mersham Road, Cr7 8np
Other householder work
Approved
Apr 2025
25/00595/HSE
262, Whitehorse Lane, Se25 6uw
Garage conversion or garage
Refused
Mar 2025
25/00040/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% (122)
88%
8 weeks
Basement
–
74% (57)
83%
8 weeks
Porch or front extension
–
88% (65)
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.