What you could build at DA14 6LN: 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.
38extensions seen within 600 m in the last 10 years
3loft 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
Mostly flats at this postcode. Flats have no permitted development rights, so almost any extension or loft conversion needs planning permission, and the freeholder's consent under the lease.
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 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.
Sept 2025
25/01587/FUL
David Lloyd Leisure Plc, Baugh Road, Da14 5ed
Other householder work
Not needed / lawful
Sept 2025
25/01479/PRIOR
8, Warwick Road, Da14 6lj
Loft or dormer
Approved
Apr 2025
25/00325/LDCP
Trident House, Grassington Road, Da14 6bz
Other householder work
Approved
Feb 2025
24/02992/PRIOR
16, Elm Road, Da14 6ad
Loft or dormer
Approved
Nov 2024
24/02270/LDCP
7c, Highview Road, Da14 4ex
Rear extension
Not needed / lawful
Feb 2024
24/00124/GPDE
29, Oxford Road, Da14 6lw
Rear extension
Approved
Dec 2023
23/02786/LDCP
1, The Lawns, Da14 4et
Rear extension
Approved
Dec 2023
23/02617/LDCP
42, Farwell Road, Da14 4lg
Rear extension
Withdrawn
Jul 2023
23/01352/GPDE
62, Sidcup Hill, Da14 6hy
Loft or dormer
Approved
Jul 2023
23/01243/LDCP
4, Oxford Road, Da14 6lw
Loft or dormer
Approved
Jun 2023
23/00917/LDCP
49, Middleton Avenue, Da14 6jj
Loft or dormer
Refused
May 2023
23/00616/LDCP
23, Sussex Road, Da14 6lg
Loft or dormer
Approved
Mar 2023
23/00208/LDCP
7, Belton Road, Da14 4ab
Rear extension
Not needed / lawful
Feb 2023
23/00047/GPDE
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.