The limits
| House type | Max depth | Distance to rear boundary |
|---|---|---|
| Detached | 3 m | At least 7 m |
| Semi-detached | 3 m | At least 7 m |
| Terraced | 3 m | At least 7 m |
| Flat or maisonette | Not permitted | Not permitted |
Other conditions
- No more than 3 m beyond the original rear wall.
- No part within 7 m of the boundary opposite the rear wall.
- Roof pitch to match the existing house, as far as practicable.
- Materials similar in appearance to the existing house.
- Upper-floor windows in a side wall must be obscure-glazed and non-opening below 1.7 m.
- Eaves and ridge no higher than those of the existing house.
When you can’t use permitted development
Flats & maisonettes
No householder permitted development rights at all.
Listed buildings
Listed building consent is needed for almost any change.
Conservation areas
Not permitted development — needs planning permission.
Article 4 directions
Your council may have removed this right on your street.
Planning conditions
An old permission may have removed permitted development rights. Not published anywhere.
New builds
Often have permitted development removed by condition. Check your deeds.
Your exact limits
Every project for your house type, with Article 4, listing and trees checked at your address.
£17.99one-off
Get my reportWhy the 7 m rule rules out most terraces
The 7 m is measured from the extension to the boundary directly behind it, not to the neighbour's house. A typical terraced garden is 10 m long or less, so a 3 m two-storey extension leaves too little room. On a longer suburban plot it usually works.
If you can't meet it, a planning application for a two-storey extension is common and often approved — the permitted development route just isn't open.
Two-storey extension rules by council
Some councils have Article 4 directions that change these limits. Pick yours to see what applies locally.
Common questions
- Can I use prior approval for a two-storey extension?
- No. The larger home extension scheme (6 m and 8 m) only covers single-storey rear extensions. Anything over 3 m on two storeys needs planning permission.
- Is a two-storey side extension permitted development?
- No. Side extensions are only permitted development when they're single storey. A two-storey side or wrap-around extension always needs planning permission.
- Can I add a balcony to the first floor?
- Not under permitted development. Balconies, verandas and raised platforms are excluded from Class A.