What you could build at BR6 8BA: 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 Crofton, Bromley.
80extensions seen within 600 m in the last 10 years
1loft conversions within 600 m in the last 10 years
98.8extensions 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 Crofton.
Move to a home 20 m² bigger (about £762,000)
Stamp duty on the new home
£28,100
Estate agent on yours 1.2% + VAT
£9,216
Solicitors, buying and selling
£3,000
Survey
£600
Removals
£1,500
Money gone
£42,416
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
−£73,200
Money gone
−£15,700
On these figures, extending loses about £58,116 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.
31, Broadcroft Road, Br5 1et
Porch or front extension
Under consideration
–
25/01440/FULL6
5, Yeovil Close, Br6 8bt
Loft or dormer
Under consideration
–
25/01223/FULL6
31, Broadcroft Road, Br5 1et
Rear extension
Not needed / lawful
May 2025
25/01438/HHPA
34, Lynwood Grove, Br6 0bg
Porch or front extension
Approved
Jun 2025
25/01085/FULL6
66, Lynwood Grove, Br6 0bh
Two-storey extension
Under consideration
–
25/00952/FULL6
41, Cathcart Drive, Br6 8bu
Loft or dormer
Approved
May 2025
25/01161/FULL6
1, Beaumont Road, Br5 1jl
Loft or dormer
Refused
May 2025
25/00767/FULL6
20, Andover Road, Br6 8bp
Rear extension
Approved
May 2025
25/00690/FULL6
5, Newstead Avenue, Br6 9rj
Side return or wrap-around
Approved
Apr 2025
25/00843/FULL6
44, Crofton Lane, Br5 1hl
Rear extension
Approved
Apr 2025
25/00358/FULL6
26, Oregon Square, Br6 8bq
Rear extension
Approved
Apr 2025
25/00403/FULL6
10, Derwent Drive, Br5 1ew
Rear extension
Refused
Apr 2025
25/00281/FULL6
11, Derwent Drive, Br5 1en
Rear extension
Approved
Mar 2025
25/00261/FULL6
4, Beckford Drive, Br5 1sh
Garage conversion or garage
Approved
Mar 2025
25/00159/FULL6
41, Cathcart Drive, Br6 8bu
Loft or dormer
Refused
Mar 2025
24/04809/FULL6
11, The Ridge, Br6 8ap
Two-storey extension
Approved
Feb 2025
24/04792/FULL6
87, Dale Wood Road, Br6 0by
Other householder work
Approved
Jan 2025
24/04546/FULL6
22, Darrick Wood Road, Br6 8aw
Garage conversion or garage
Approved
Jan 2025
24/04239/FULL6
56, Sparrow Drive, Br5 1rz
Rear extension
Approved
Dec 2024
24/03913/HHPA
2, Pound Court Drive, Br6 8ah
Loft or dormer
Approved
Dec 2024
24/03790/FULL6
15, Darrick Wood Road, Br6 8an
Loft or dormer
Approved
Nov 2024
24/03673/FULL6
27, Allington Road, Br6 8ay
Rear extension
Approved
Jan 2025
24/03515/FULL6
46, Lynwood Grove, Br6 0bh
Outbuilding or garden room
Approved
Oct 2024
24/03259/FULL6
9, Beckford Drive, Br5 1sh
Rear extension
Approved
Oct 2024
24/03053/FULL6
48, Ferndown Avenue, Br6 8df
Windows, doors or cladding
Approved
Oct 2024
24/03103/FULL6
27, Woodcote Drive, Br6 8db
Rear extension
Approved
Sept 2024
24/02899/HHPA
31, Dale Wood Road, Br6 0by
Two-storey extension
Approved
Sept 2024
24/02587/FULL6
1a, St Thomas Drive, Br5 1he
Garage conversion or garage
Approved
Jul 2024
24/02119/FULL6
21, Lynwood Grove, Br6 0bd
Loft or dormer
Refused
Jan 2025
24/01951/FULL6
63, Lynwood Grove, Br6 0bq
Loft or dormer
Approved
Jul 2024
24/01768/FULL6
1, The Ridge, Br6 8ap
Loft or dormer
Approved
Jun 2024
24/01355/FULL6
62, Oregon Square, Br6 8bg
Loft or dormer
Approved
May 2024
24/00945/FULL6
53, Crofton Lane, Br5 1hj
Rear extension
Approved
Apr 2024
23/04937/FULL6
147, Crofton Road, Br6 8ja
Rear extension
Approved
Apr 2024
24/00541/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
86% (7)
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.