Do I Need Planning Permission for an Annexe?
Usually YES
In most cases, YES — a self-contained annexe with its own kitchen and bathroom usually requires planning permission as a separate dwelling.
Keep reading for the full rules.
An annexe — a self-contained unit attached to or in the grounds of the main house — is one of the most complex planning topics. Whether one needs planning permission depends on how "self-contained" it is. An incidental use (e.g., a granny flat that is not self-sufficient) may be PD; a fully separate dwelling almost always needs permission.
Permitted Development Rules by Region
Permitted Development Rules — England
- ✓A structure used purely as ancillary accommodation (home office, guest room) may not need planning permission.
- ✓A self-contained unit with its own kitchen, bathroom, and separate entrance is likely to be treated as a separate dwelling and require planning permission.
- ✓An annexe within the main house (e.g., a ground-floor extension used by a relative) may not need planning permission as a change of use.
- ✓An outbuilding converted to an annexe almost certainly requires planning permission.
Size & Position Limits (England)
| Requirement | Limit / Rule |
|---|---|
| Self-contained unit (own kitchen/bathroom) | Planning permission required (change of use to dwelling) |
| Ancillary accommodation (no kitchen) | May be PD as outbuilding or extension |
| Listed buildings | Listed building consent required |
| Article 4 areas | PD rights may be restricted |
When Do You Need Planning Permission?
Even if your project is usually permitted development, planning permission is required in these circumstances:
- ✗The annexe will be a self-contained dwelling with its own kitchen and bathroom.
- ✗The annexe will be occupied by someone who is not part of the main household.
- ✗You want to build a new structure specifically for an annexe.
What Happens If You Build Without Permission?
An unauthorised annexe may be the subject of an enforcement notice. The council can also refuse to allow the annexe to be rented separately without planning permission.
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.