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 one of the most common types of house extension in England. 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. For breaches that began on or after 25 April 2024, the general enforcement period in England is 10 years; the former four-year period can still apply to certain development substantially completed before that date. 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 breaches beginning on or after 25 April 2024, the general enforcement period in England is 10 years. Transitional rules preserve the former four-year period for certain earlier breaches. There is no time limit for listed building enforcement.