Garden rooms and annexes – size, height and use
Outbuilding rules under permitted development: 2.5 m height near boundaries, 4 m dual-pitched roof, and when an annexe needs planning permission.
Reading time about 5 minutes
Outbuilding limits
Under PD an outbuilding must be single-storey and used for purposes incidental to the house.
Sleeping in it changes things
A garden office or gym is incidental use. A self-contained annexe with bedroom, kitchen and bathroom normally needs planning permission and must meet Building Regulations.
Frequently asked questions
Can I rent out a garden annexe?
Usually not without planning permission, as it becomes a separate dwelling.
Rules change and are applied locally. Always check with your local planning authority and Building Control before you build.