This is general guidance based on standard permitted development rights in England. Rules differ for listed buildings, conservation areas, and properties with Article 4 directions. Always confirm with your local planning authority before starting work.
Do I Need Planning Permission for a Annexe or Granny Flat?
A self-contained living space for a family member, either as an extension to the main house or as a separate building in the garden. The key planning issue is whether the annexe is ancillary to the main dwelling or constitutes a separate dwelling.
The General Position
Whether you need planning permission depends on the specific details of your project, your property type, and your location. Check the conditions below carefully.
Whether an annexe is permitted development depends on how it is built and used. If attached to the main house, standard extension PD rules apply. If a separate building in the garden, it may be PD under Part 1, Class E (outbuildings), provided it is used for purposes incidental to the enjoyment of the main dwelling and is not a self-contained separate home.
Conditions and Requirements
- 1Must be used for purposes ancillary (incidental) to the main dwelling
- 2Must not be used as, or let as, a separate independent dwelling
- 3If an outbuilding: same size and height limits as other outbuildings
- 4If an extension: same PD rules as rear or side extensions
- 5The annexe should not have a separate postal address, council tax bill, or utility accounts
Size and Dimension Limits
- If outbuilding: max height 2.5m within 2m of boundary, otherwise 4m (dual pitch) or 3m (other)
- If extension: same limits as the relevant extension type
- Must not cover more than half the curtilage
When Permitted Development Does Not Apply
- Creating a separate dwelling requires planning permission and potentially a change of use
- Council tax implications if the annexe is assessed as a separate dwelling
- Sleeping accommodation in outbuildings is a grey area; discuss with your LPA
- Not permitted development if forward of the principal elevation
What About Building Regulations?
Building Regulations apply to any habitable accommodation. Covers structural stability, fire safety and escape routes, thermal insulation, ventilation, drainage (if including kitchen or bathroom facilities), electrical installations, and accessibility standards.
Building regulations are separate from planning permission. You may need both, one, or neither depending on your project. Building regulations cover the safety and quality of building work, including structural integrity, fire safety, insulation, ventilation, and drainage.
How to Apply for Planning Permission
Check if you need permission
Review the permitted development rules above. If in doubt, contact your council or apply for a Lawful Development Certificate.
Prepare your application
You will need scaled drawings, a site plan, and a completed application form. An architect or planning consultant can help with this.
Submit to your local council
Applications can be submitted online via the Planning Portal or directly to your council. Select your council below for a direct link.
Wait for a decision
8 weeks for householder planning applications..
Application cost: £258.
What Happens If I Build Without Permission?
Enforcement risk is high if the annexe is used as a separate dwelling without permission. The council can serve an enforcement notice requiring cessation of independent use. This applies regardless of whether the building itself was PD. Using an annexe as a separate rental property without PP is a breach of planning control.
Find a Builder for Your Annexe or Granny Flat
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Select Your Council
Choose your local council for guidance specific to your area, including links to apply and whether your council has conservation areas or Article 4 directions that could affect your project.
London
South East
South West
East of England
East Midlands
West Midlands
North East
North West
Yorkshire and the Humber
CA = has conservation areas. A4 = has Article 4 directions. These may restrict your permitted development rights.