Do I Need Planning Permission for an Annexe?
An annexe in the garden (for a relative, home office, or rental) is one of the most complex PD areas. Whether you need planning depends on the size, use, and whether it constitutes a separate dwelling.
Outbuildings under PD
Outbuildings under PD
You can build outbuildings (including potential annexes) under PD if they are: single storey with a maximum eaves height of 2.5m, maximum overall height of 4m (dual pitch) or 3m (flat roof or within 2m of boundary), not exceeding 50% of the curtilage, and not forward of the principal elevation. These are 'incidental to the enjoyment of the dwelling' — a term that causes most of the confusion.
The 'separate dwelling' problem
PD allows outbuildings incidental to the main house. If the outbuilding is used as a separate, self-contained dwelling (with its own entrance, kitchen, bathroom, and separate living arrangements), it may require planning permission as a change of use. An annexe for a family member who shares facilities with the main house is generally fine. A self-contained flat for rental is not.
Common questions
Frequently asked questions
Extension guides
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Planning permission for annexes — when PD applies, when you need a full application, and the rules on creating a separate dwelling.
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