Do I Need Planning Permission for a Single-Storey Extension?
IT DEPENDS
IT DEPENDS — a single-storey rear extension may be permitted development, but size, position, and location all matter. Side and front extensions are more restricted.
Keep reading for the full rules.
Single-storey extensions can often be built under permitted development rights, but this depends on the size, position, and whether you live in a designated area. Rear extensions are most likely to qualify as PD; side and front extensions are much more restricted.
Permitted Development Rules by Region
Permitted Development Rules — England
- ✓Rear extensions can be up to 3 metres deep (attached house) or 4 metres deep (detached house) under standard PD rights.
- ✓Under the Neighbour Consultation Scheme (prior approval), rear extensions up to 6 metres (attached) or 8 metres (detached) may be permitted.
- ✓Side extensions can be PD if they are no more than half the width of the original house.
- ✓Front extensions are generally NOT permitted development.
- ✓The extension must not be higher than 4 metres or higher than the eaves.
- ✓Materials must match or be similar in appearance to the existing house.
- ✓Cannot cover more than 50% of the garden.
Size & Position Limits (England)
| Requirement | Limit / Rule |
|---|---|
| Max rear depth (attached) | 3m (or 6m with prior approval) |
| Max rear depth (detached) | 4m (or 8m with prior approval) |
| Max height | 4 metres (or eaves height) |
| Max side width | 50% of original house width |
| Max garden coverage | 50% of original garden |
| Materials | Must match or be similar to the original house |
When Do You Need Planning Permission?
Even if your project is usually permitted development, planning permission is required in these circumstances:
- ✗A front extension (in almost all cases).
- ✗A side extension wider than half the original house width.
- ✗A rear extension deeper than 3m (attached) or 4m (detached) under standard PD.
- ✗Any extension on a flat or maisonette.
- ✗Extensions in conservation areas that extend beyond the rear wall.
- ✗Your property is a listed building — you will need listed building consent.
- ✗Your council has removed PD rights via an Article 4 Direction.
What Happens If You Build Without Permission?
The council has 4 years to take enforcement action against unauthorised development on a dwelling house. A retrospective planning application (householder) may resolve the issue if the work does not comply with PD rules.
Enforcement notices: Your council can issue an enforcement notice requiring you to stop the work, remove it, or restore the land to its original condition. You have a right of appeal against an enforcement notice.
Retrospective applications: If you have already carried out work that required planning permission, you can submit a retrospective planning application. If approved, this regularises the work. If refused, you may be required to remove it.
Time limits: For dwelling houses, the council generally has 4 years to take enforcement action for most types of work. For breaches of planning conditions, the time limit is 10 years. There is no time limit for listed building enforcement.