Do I need planning permission for a two-storey extension in London?
Often yes. A two-storey rear extension is permitted development only if it goes no further than 3 metres beyond the rear wall and stays at least 7 metres from the boundary opposite, and the right does not exist in a conservation area. So measure the garden before anything is designed.
Prefer to talk it through?
The two numbers that decide it
For an extension of more than one storey, the General Permitted Development Order sets two limits. It must not extend beyond the rear wall of the original house by more than 3 metres, and it must not be within 7 metres of any boundary of the curtilage opposite the rear wall (GPDO 2015, Schedule 2, Part 1, Class A.1(h)).
Measure from the back of your house to the fence at the far end of the garden. If that distance is under 7 metres plus the depth you want to build, the extension fails the second test, and a planning application is the route.
Where the right does not exist at all
On article 2(3) land, which includes conservation areas, Class A does not permit an extension of more than a single storey beyond the rear wall. The same land bars cladding and extensions beyond a side wall.
Our Article 4 glossary entry covers the other way the right can disappear, a direction made by the council for a street or an area.
A householder planning application costs £548 from 1 April 2026.
Details that catch out permitted schemes
Where the enlarged part is within 2 metres of the boundary, its eaves must not be higher than 3 metres. An upper-floor window in a side wall must be obscure-glazed and non-opening unless its openable part is more than 1.7 metres above the floor.
A scheme that otherwise looks permitted can fail on either point, so we check them on the drawings before you commit.
The fee and what we draw
A householder planning application costs £548 from 1 April 2026. Our starting fixed fee for double storey extension planning drawings is £995, survey included, and the double storey extension drawings page lists what it covers.
If a neighbour shares a wall with you, read about the Party Wall Act before building starts. The lawful development certificate drawings service is the way to prove a permitted scheme.
Sources
Every figure on this page, where it comes from and a link to the original.
| Figure | Source | Link |
|---|---|---|
| 3 metres | GPDO 2015 Sch 2 Pt 1 Class A.1(h)(i): an extension of more than one storey must not extend beyond the rear wall of the original house by more than 3 metres (source wording: "by more than 3 metres") | www.legislation.gov.uk |
| 7 metres | GPDO 2015 Sch 2 Pt 1 Class A.1(h)(ii): an extension of more than one storey must not be within 7 metres of any boundary of the curtilage opposite the rear wall (source wording: "be within 7 metres of any boundary of the curtilage") | www.legislation.gov.uk |
| 2 metres | GPDO 2015 Sch 2 Pt 1 Class A.1(i): where the enlarged part is within 2 metres of the curtilage boundary, its eaves must not exceed 3 metres (source wording: 2 metres) | www.legislation.gov.uk |
| article 2(3) land | GPDO 2015 Sch 2 Pt 1 Class A.2: on article 2(3) land (which includes conservation areas) Class A does not permit cladding, extensions beyond a side elevation wall, or an extension of more than one storey beyond the rear wall (source wording: "have more than a single storey and extend beyond the rear wall of the original dwellinghouse") | www.legislation.gov.uk |
| 1.7m | GPDO 2015 Sch2 Pt1 Class B para B.2(c) / Class A para A.3(b): side-elevation windows obscure-glazed and non-opening unless openable parts more than 1.7 metres above floor (source wording: 1.7 metres) | www.legislation.gov.uk |
| £548 | Fees for planning applications in England from 1 April 2026 (MHCLG, SI 2012/2920 as annually indexed), category 6(1): householder application for the enlargement, improvement or alteration of a single dwellinghouse (source wording: £548) | assets.publishing.service.gov.uk |
| £995 | DrawingsDirect starting fixed fee for double storey extension planning drawings (survey included), from the published price list | drawingsdirect.co.uk |
Questions people ask
Do you need planning permission for a two storey extension?
Can I build a two storey extension in a conservation area?
How much does it cost to apply?
Photographs: David Hawgood (CC BY-SA 2.0).
