Do I need planning permission for a garden office?
Most garden rooms are built under permitted development. The height limits are stricter than the kits on sale suggest, and there is a use restriction that catches a lot of people.
The core conditions
Outbuildings are covered by Class E of the permitted development rules. To build without planning permission, all of the following must be true.
- The building is within the curtilage of the house, meaning your garden or the land around it.
- It is not forward of the principal elevation, meaning it cannot go in the front garden.
- It is single storey.
- Together with any extensions, it does not cover more than 50 percent of the land around the original house.
- It is for a purpose incidental to the enjoyment of the house.
Height limits
| Situation | Maximum height |
|---|---|
| Dual pitched roof | 4 metres |
| Any other roof | 3 metres |
| Within 2 metres of a boundary | 2.5 metres, whatever the roof shape |
That last row is the one that catches most people. A great many garden offices are placed against a rear or side fence to keep the lawn usable, and at that position the whole building has to come in under 2.5 metres including the roof. Plenty of flat roof garden rooms sold as permitted development are close to 2.5 metres before you add a base, and the height is measured from the highest ground next to the building.
Eaves height is also capped at 2.5 metres anywhere on the plot.
The incidental use restriction
Permitted development for outbuildings covers uses that are incidental to the enjoyment of the house. A home office, gym, studio, playroom, storage or a home cinema all sit comfortably within that.
What does not sit within it is separate living accommodation. If your garden building has a bed, a kitchen and a bathroom and could function as an independent dwelling, it stops being incidental and becomes a separate use, which needs planning permission. Councils do enforce this, and it also creates council tax and building regulations consequences.
Running a business from a garden office is usually fine if the business is compatible with residential use, meaning no significant increase in visitors, deliveries or noise. A one person consultancy is not a problem. A dog grooming business with clients arriving all day probably is.
Where the rules change
Listed buildings
Permitted development rights for outbuildings do not apply within the curtilage of a listed building. Not restricted, removed. Any garden building at a listed property needs planning permission, and probably listed building consent as well.
Conservation areas
Outbuildings to the side of the original house are restricted in conservation areas. Buildings behind the house are generally still fine within the usual limits.
AONBs, National Parks and the Broads
Additional restrictions apply in designated landscapes. The allowance for outbuildings more than 20 metres from the house is reduced to 10 square metres.
Article 4 directions
As with everything else, a local Article 4 direction can remove these rights. Check with your council.
Building regulations and garden rooms
Many garden buildings are exempt from building regulations, but not all. As a rough guide, a detached single storey building under 15 square metres of floor area with no sleeping accommodation is generally exempt. Between 15 and 30 square metres it can still be exempt if it is at least one metre from any boundary or built substantially of non combustible materials.
Anything with sleeping accommodation needs building regulations approval regardless of size. Electrical work in an outbuilding is notifiable under Part P and needs to be done or certified by a competent electrician.
Hard surfaces and driveways
While you are planning the garden, one related rule. Laying a permeable surface, or one that drains to a permeable area, does not need permission. Laying more than 5 square metres of non permeable surface between the house and a highway does need planning permission. This is why so many block paved front drives are built with permeable joints.
Check before you order the building
casaQ tells you which constraints apply to your address, so you know whether your garden building needs permission before you spend anything.
Check your address freeCommon questions
How tall can my garden office be?
Four metres with a dual pitched roof, three metres with any other roof, but only 2.5 metres if any part of it is within 2 metres of a boundary. Height is measured from the highest ground level next to the building.
Can I sleep in my garden office?
Not under permitted development. Sleeping accommodation takes the building outside incidental use, which means it needs planning permission as a separate dwelling or annexe, and it will need building regulations approval.
Can I run a business from a garden office?
Usually yes, if the character of the property stays residential. Problems arise where the business generates visitors, deliveries, noise or parking pressure. If in doubt, ask your council whether a material change of use has occurred.
Does a garden office need building regulations?
Often not, if it is under 15 square metres with no sleeping accommodation. Between 15 and 30 square metres it can be exempt subject to boundary distance or non combustible construction. Electrical work always needs to comply with Part P.
Does a garden office affect the 50 percent rule for extensions?
Yes. Outbuildings and extensions are counted together. A large garden room can use up allowance you were planning to spend on an extension later, so think about both at the same time.