Do I Need Planning Permission for a Rear Extension?
IT DEPENDS
A single-storey rear extension is often permitted development — up to 3 metres deep for an attached house or 4 metres for a detached house. Under the Neighbour Consultation Scheme you can go up to 6 or 8 metres with prior approval. Double-storey rear extensions almost always need full planning permission.
Keep reading for the full rules.
A rear extension is the most common type of house extension in the UK. Single-storey rear extensions are frequently permitted development (PD), meaning no planning application is required — but size limits, height rules, and local restrictions must all be met. Double-storey rear extensions are much more restricted and generally require a full planning application.
Permitted Development Rules by Region
Permitted Development Rules — England
- ✓Single-storey rear extensions must not exceed 3 metres in depth beyond the rear wall for an attached house, or 4 metres for a detached house, under standard PD rights.
- ✓Under the Neighbour Consultation Scheme (also called prior approval), a single-storey rear extension can be up to 6 metres deep (attached) or 8 metres deep (detached) — the council must be notified and neighbours given the opportunity to object.
- ✓The extension must not be higher than 4 metres at the eaves or ridge, and must not exceed the height of the existing roof.
- ✓Double-storey rear extensions must not be within 7 metres of the rear boundary.
- ✓All extensions must not cover more than 50% of the original garden.
- ✓Materials must be similar in appearance to the existing house.
Size & Position Limits (England)
| Requirement | Limit / Rule |
|---|---|
| Max depth — single storey, attached | 3m (6m with prior approval) |
| Max depth — single storey, detached | 4m (8m with prior approval) |
| Max eaves height — single storey | 4m |
| Double-storey rear boundary setback | Must be 7m or more from the rear boundary |
| Max garden coverage | 50% of original garden |
When Do You Need Planning Permission?
Even if your project is usually permitted development, planning permission is required in these circumstances:
- ✗You want a single-storey extension deeper than 3 metres (attached) or 4 metres (detached) and have not used the prior approval route.
- ✗You are building a double-storey rear extension that does not meet PD conditions.
- ✗Your property is in a conservation area, National Park, AONB, or World Heritage Site.
- ✗Your property is a listed building — listed building consent is also required.
- ✗You have already used your PD allowance with previous extensions.
- ✗Your council has an Article 4 Direction removing permitted development rights.
What Happens If You Build Without Permission?
Building a rear extension without the required planning permission can result in an enforcement notice from the council, requiring demolition or alteration. The enforcement time limit for dwellinghouses is 4 years. A retrospective householder application may regularise the works, but success is not guaranteed.
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.