What you could build at TW1 4AG: 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 Twickenham Town, Richmond upon Thames.
106extensions seen within 600 m in the last 10 years
13loft conversions within 600 m in the last 10 years
121.8extensions 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
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 Twickenham Town.
Move to a home 20 m² bigger (about £883,000)
Stamp duty on the new home
£34,150
Estate agent on yours 1.2% + VAT
£10,224
Solicitors, buying and selling
£3,000
Survey
£600
Removals
£1,500
Money gone
£49,474
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
−£103,800
Money gone
−£46,300
On these figures, extending loses about £95,774 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.
Other householder work
Refused
Aug 2026
PA26/2290
5, The Embankment, Tw1 3du
Windows, doors or cladding
Approved
Aug 2026
PA26/1981
46, Grove Avenue, Tw1 4hy
Side extension
Approved
Aug 2026
PA26/2142
18, Radnor Gardens, Tw1 4na
Loft or dormer
Approved
Aug 2026
PA26/1782
41, Upper Grotto Road, Tw1 4ng
Loft or dormer
Approved
Jul 2026
PA26/1828
3, Strafford Road, Tw1 3ad
Loft or dormer
Approved
Sept 2026
PA26/1479
36 40, Holly House, Heath Road, Tw1 4bz
Other householder work
Refused
Jul 2026
PA26/1747
19, Copthall Gardens, Tw1 4hh
Rear extension
Under consideration
–
PA26/1624
17, Canham House, 17 Heath Road, Tw1 4aw
Loft or dormer
Under consideration
–
PA26/1529
59, Sherland Road, Tw1 4hb
Side return or wrap-around
Under consideration
–
PA26/1376
57, Sherland Road, Tw1 4hb
Side return or wrap-around
Under consideration
–
PA26/1452
17, Heath Gardens, Tw1 4ly
Side return or wrap-around
Approved
May 2026
PA26/1406
49, Copthall Gardens, Tw1 4hh
Rear extension
Under consideration
–
PA26/1061
61, Grove Avenue, Tw1 4hx
Side return or wrap-around
Under consideration
–
PA26/1212
28, Poulett Gardens, Tw1 4qr
Loft or dormer
Under consideration
–
PA26/0731
16, Cornwall Road, Tw1 3ls
Other householder work
Approved
Apr 2026
PA26/0650
13, Tennyson Avenue, Tw1 4qx
Rear extension
Under consideration
–
PA26/0761
14, Station Yard, Tw1 4lj
Rear extension
Approved
Apr 2026
PA26/0511
39, Upper Grotto Road, Tw1 4ng
Rear extension
Approved
Apr 2026
PA26/0529
32, Grove Avenue, Tw1 4hy
Side return or wrap-around
Approved
Apr 2026
PA26/0499
Jacobs Ladder, Eel Pie Island, Tw1 3dy
Other householder work
Approved
Mar 2026
PA26/0179
81, Lion Road, Tw1 4ht
Rear extension
Approved
Feb 2026
PA26/0141
51, Copthall Gardens, Tw1 4hh
Rear extension
Approved
Mar 2026
PA25/4575
3, Cross Deep Gardens, Tw1 4qz
Rear extension
Approved
Feb 2026
PA25/4446
13, Bell Lane, Tw1 3nu
Loft or dormer
Approved
Feb 2026
PA25/3920
34, Upper Grotto Road, Tw1 4nf
Rear extension
Approved
Jan 2026
PA25/4267
26, Amyand Park Road, Tw1 3he
Loft or dormer
Approved
Jan 2026
PA25/4140
21, Holmes Road, Tw1 4rf
Side return or wrap-around
Approved
Dec 2025
PA25/4016
23 - 25, King Street, Tw1 3sd
Other householder work
Approved
Dec 2025
PA25/4153
15, Cornwall Road, Tw1 3ls
Side return or wrap-around
Approved
Dec 2025
PA25/4004
26, Amyand Park Road, Tw1 3he
Other householder work
Other
–
PA25/3686
1, Grove Avenue, Tw1 4hx
Side return or wrap-around
Approved
Nov 2025
PA25/3325
51, Copthall Gardens, Tw1 4hh
Loft or dormer
Approved
Nov 2025
PA25/3389
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.
–
88%
8 weeks
Basement
–
–
83%
9 weeks
Porch or front extension
80% (5)
–
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.