What you could build at DA8 1QE: 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 Erith West, Bexley.
36extensions seen within 600 m in the last 10 years
1loft conversions within 600 m in the last 10 years
54.3extensions 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 (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 Erith West.
Move to a home 20 m² bigger (about £455,000)
Stamp duty on the new home
£12,750
Estate agent on yours 1.2% + VAT
£5,328
Solicitors, buying and selling
£3,000
Survey
£600
Removals
£1,500
Money gone
£23,178
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
−£51,000
Money gone
£6,500
On these figures, extending loses about £16,678 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.
Refused
Aug 2026
26/01252/GPDE
9, Oakdene Avenue, Da8 1ej
Rear extension
Approved
Jul 2026
26/01115/LDCP
192a, Riverdale Road, Da8 1qf
Outbuilding or garden room
Approved
Jul 2026
26/00778/LDCP
81, Holly Hill Road, Da8 1qb
Side extension
Approved
Apr 2026
26/00338/LDCP
192a, Riverdale Road, Da8 1qf
Outbuilding or garden room
Refused
Apr 2026
26/00296/LDCP
151, Erith Road, Da17 6hs
Loft or dormer
Approved
Dec 2025
25/02130/LDCP
9, Rutland Gate, Da17 6hq
Rear extension
Refused
Dec 2025
25/02133/LDCP
21, Athol Road, Da8 1pt
Rear extension
Not needed / lawful
Nov 2025
25/01923/GPDE
50a, Erith Road, Da17 6ey
Rear extension
Approved
Nov 2025
25/01979/LDCP
27, Carlton Road, Da8 1dn
Rear extension
Approved
Oct 2025
25/01662/FUL
15, Swaylands Road, Da17 6ls
Rear extension
Refused
Jun 2025
25/00949/GPDE
264, Brook Street, Da8 1dz
Rear extension
Not needed / lawful
Jul 2024
24/01752/GPDE
54, Riverdale Road, Da8 1px
Outbuilding or garden room
Approved
Jul 2024
24/01459/LDCP
37, Carlton Road, Da8 1dr
Loft or dormer
Approved
Mar 2024
24/00105/LDCP
264, Brook Street, Da8 1dz
Rear extension
Refused
Dec 2023
23/03075/GPDE
28, The Drive, Da8 1ed
Rear extension
Not needed / lawful
Sept 2023
23/01811/GPDE
62, Holly Hill Road, Da8 1qd
Loft or dormer
Approved
Jun 2023
23/00790/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.