What you could build at BR5 2DP: 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 St Mary Cray South, Bromley.
64extensions seen within 600 m in the last 10 years
0loft conversions within 600 m in the last 10 years
83.2extensions 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 St Mary Cray South.
Move to a home 20 m² bigger (about £571,000)
Stamp duty on the new home
£18,550
Estate agent on yours 1.2% + VAT
£6,624
Solicitors, buying and selling
£3,000
Survey
£600
Removals
£1,500
Money gone
£30,274
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
−£66,600
Money gone
−£9,100
On these figures, extending loses about £39,374 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.
22, Sefton Road, Br5 1rq
Rear extension
Not needed / lawful
Apr 2025
25/00845/HHPA
4, Petts Wood Road, Br5 1lb
Loft or dormer
Refused
Feb 2025
24/04787/FULL6
4, Grosvenor Road, Br5 1qu
Two-storey extension
Refused
Feb 2025
24/04687/FULL6
23, Scads Hill Close, Br6 0eb
Rear extension
Approved
Jan 2025
24/04475/FULL6
47, Friar Road, Br5 2bw
Loft or dormer
Approved
Mar 2025
24/04478/FULL6
201, Chislehurst Road, Br5 1np
Side extension
Refused
May 2025
24/04174/FULL6
201, Chislehurst Road, Br5 1np
Other householder work
Refused
May 2025
24/04175/FULL6
28, Petts Wood Road, Br5 1lb
Loft or dormer
Refused
Dec 2024
24/04087/FULL6
32, Forest Way, Br5 2aq
Rear extension
Approved
Dec 2024
24/03171/FULL6
4, Petts Wood Road, Br5 1lb
Two-storey extension
Approved
Oct 2024
24/03145/FULL6
23, Sefton Road, Br5 1rg
Rear extension
Approved
Aug 2024
24/02565/FULL6
10, Ladywood Avenue, Br5 1qj
Rear extension
Approved
Aug 2024
24/02134/FULL6
56, Cray Valley Road, Br5 2ez
Two-storey extension
Approved
Oct 2024
24/01950/FULL6
2, Ascot Road, Br5 2jf
Side extension
Approved
Jul 2024
24/01917/FULL6
52, Kedleston Drive, Br5 2dr
Rear extension
Approved
Jul 2024
24/01743/FULL6
9, Petts Wood Road, Br5 1jt
Loft or dormer
Approved
Sept 2024
24/01111/FULL6
1, Sefton Road, Br5 1rg
Side extension
Approved
May 2024
24/00944/FULL6
32, Forest Way, Br5 2aq
Rear extension
Approved
May 2024
24/00901/FULL6
20, Sutherland Avenue, Br5 1qz
Loft or dormer
Approved
May 2024
24/00857/FULL6
214, Chislehurst Road, Br5 1nr
Loft or dormer
Approved
Jul 2024
24/00158/FULL6
22, Princes Avenue, Br5 1qs
Loft or dormer
Refused
Apr 2024
24/00440/FULL6
160, Chislehurst Road, Br6 0dt
Two-storey extension
Approved
Feb 2024
23/04947/FULL6
1, Sherborne Road, Br5 1gx
Rear extension
Under consideration
–
23/04403/FULL6
59, Sutherland Avenue, Br5 1qy
Loft or dormer
Approved
Feb 2024
23/04474/FULL6
56, Sutherland Avenue, Br5 1rb
Rear extension
Approved
Jan 2024
23/04506/FULL6
17, Grosvenor Road, Br5 1qt
Windows, doors or cladding
Refused
Jan 2024
23/04477/FULL6
75, Lockesley Drive, Br5 2ab
Rear extension
Approved
Jan 2024
23/04278/FULL6
22, Princes Avenue, Br5 1qs
Loft or dormer
Refused
Jan 2024
23/04389/FULL6
155, Poverest Road, Br5 2dy
Side extension
Approved
Dec 2023
23/04202/FULL6
21, Sefton Road, Br5 1rg
Side return or wrap-around
Approved
Dec 2023
23/04031/FULL6
55, Hayfield Road, Br5 2dl
Side extension
Approved
Dec 2023
23/03974/FULL6
164, Chislehurst Road, Br6 0dt
Loft or dormer
Approved
Dec 2023
23/03968/FULL6
29, Friar Road, Br5 2bn
Rear extension
Approved
Dec 2023
23/03922/FULL6
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.
–
85% (123)
88%
8 weeks
Basement
–
77% (26)
83%
9 weeks
Porch or front extension
–
92% (94)
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.