What you could build at DA14 4PF: 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 Sidcup East, Bexley.
68extensions seen within 600 m in the last 10 years
0loft conversions within 600 m in the last 10 years
60.6extensions 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 Sidcup East.
Move to a home 20 m² bigger (about £561,000)
Stamp duty on the new home
£18,050
Estate agent on yours 1.2% + VAT
£6,624
Solicitors, buying and selling
£3,000
Survey
£600
Removals
£1,500
Money gone
£29,774
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
−£60,600
Money gone
−£3,100
On these figures, extending loses about £32,874 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.
36, Foots Cray Lane, Da14 4nr
Loft or dormer
Approved
Apr 2026
26/00414/LDCP
30, Eaton Road, Da14 4pe
Rear extension
Not needed / lawful
Mar 2026
26/00197/GPDE
33, Wren Road, Da14 4ly
Loft or dormer
Approved
Mar 2026
26/00188/LDCP
88, Foots Cray Lane, Da14 4nr
Loft or dormer
Approved
Mar 2026
26/00127/LDCP
2, Rutland Close, Da5 3hy
Rear extension
Not needed / lawful
Jan 2026
25/02617/GPDE
26, Eaton Road, Da14 4pe
Rear extension
Refused
Jan 2026
25/02389/LDCP
16, Pembury Crescent, Da14 4qd
Rear extension
Approved
Dec 2025
25/02220/LDCP
126, Foots Cray Lane, Da14 4ns
Loft or dormer
Approved
Nov 2025
25/02034/LDCP
15, Eaton Road, Da14 4pe
Rear extension
Approved
Oct 2025
25/01829/FUL
193, Bexley Lane, Da14 4jq
Two-storey extension
Approved
Oct 2025
25/01759/FUL
20, Onslow Drive, Da14 4pb
Two-storey extension
Under consideration
–
25/01676/FUL
47, Maylands Drive, Da14 4sb
Rear extension
Approved
Sept 2025
25/01621/FUL
114, Longmead Drive, Da14 4nz
Rear extension
Approved
Sept 2025
25/01475/FUL
427, Hurst Road, Da5 3lg
Loft or dormer
Approved
Sept 2025
25/01525/FUL
3, Onslow Drive, Da14 4pb
Rear extension
Approved
Aug 2025
25/01236/LDCP
44, Stansted Crescent, Da5 3jb
Loft or dormer
Refused
Jul 2025
25/01121/LDCP
26, Eynsford Crescent, Da5 3jf
Loft or dormer
Approved
Jul 2025
25/01089/LDCP
3, Onslow Drive, Da14 4pb
Loft or dormer
Approved
Jul 2025
25/00988/LDCP
21, Eynsford Crescent, Da5 3jd
Rear extension
Not needed / lawful
May 2025
25/00699/GPDE
66, Pembury Crescent, Da14 4qd
Loft or dormer
Approved
May 2025
25/00561/LDCP
31, Carisbrooke Avenue, Da5 3hr
Loft or dormer
Approved
Apr 2025
25/00353/LDCP
35, Wren Road, Da14 4ly
Loft or dormer
Approved
Apr 2025
25/00298/LDCP
63, Foots Cray Lane, Da14 4np
Rear extension
Withdrawn
Jan 2025
24/03016/GPDE
63, Foots Cray Lane, Da14 4np
Loft or dormer
Withdrawn
Jan 2025
24/03019/LDCP
63, Foots Cray Lane, Da14 4np
Outbuilding or garden room
Withdrawn
Jan 2025
24/03021/LDCP
429, Hurst Road, Da5 3lg
Rear extension
Refused
Feb 2025
24/03000/LDCP
27, Burnham Road, Da14 4py
Rear extension
Approved
Oct 2024
24/02327/LDCP
44, Valentine Avenue, Da5 3he
Loft or dormer
Approved
Oct 2024
24/02211/LDCP
11, Melville Road, Da14 4lu
Rear extension
Approved
Jul 2024
24/01665/LDCP
111a, Longmead Drive, Da14 4ny
Loft or dormer
Refused
Mar 2024
24/00472/LDCP
22, Cotleigh Avenue, Da5 3hu
Loft or dormer
Refused
Mar 2024
24/00315/LDCP
90, Steynton Avenue, Da5 3hg
Rear extension
Not needed / lawful
Dec 2023
23/02829/GPDE
58, Princes Close, Da14 4rh
Loft or dormer
Approved
Dec 2023
23/02471/LDCP
59, Princes Close, Da14 4rh
Loft or dormer
Approved
Jul 2023
23/01189/LDCP
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.
–
81% (67)
88%
8 weeks
Basement
–
–
83%
9 weeks
Porch or front extension
–
81% (16)
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.