Do I Need Planning Permission for a Garden Room?

Answer a few questions about your plot and your garden room. This checks the permitted development rules for England and flags when you would likely need a planning application.

Permitted development rules apply to England only. Scotland, Wales and Northern Ireland have their own rules. This is general guidance, not a legal ruling. Always confirm with your local planning authority before you build.

Is your home a house, or a flat / maisonette?

Is the property in a Conservation Area, National Park, AONB, the Broads, or is it listed?

Where will it sit relative to the house?

Roof type

Overall height to the top of the roof (m)

Eaves height (the lowest edge of the roof) (m)

Distance from the nearest boundary at the closest point (m)

Total ground covered by this plus all existing outbuildings (m²)

Area of the garden around the house, excluding the house footprint (m²)

It will be used for sleeping / as self-contained living accommodation

Checking…

The rules this checks (England)

A garden room is usually an outbuilding under Class E permitted development. It typically does not need planning permission when all of these hold true:

It is single storey, with a maximum eaves height of 2.5 m.
Maximum overall height is 4 m for a dual-pitched roof, or 3 m for any other roof.
If it is within 2 m of any boundary, the maximum overall height is 2.5 m.
It sits to the rear, not forward of the principal elevation that fronts a road.
Outbuildings in total cover no more than 50% of the land around the original house.
It is not used as separate, self-contained living accommodation or for sleeping.

On designated land (Conservation Areas, National Parks, AONBs, the Broads), outbuildings to the side of the house are not permitted development, and tighter limits apply. Listed buildings almost always need listed building consent for outbuildings in their grounds. Flats and maisonettes do not get these outbuilding rights at all.

Even when planning permission is not needed, building regulations may still apply, for example if the floor area is over 15 m² and within 1 m of a boundary, or over 30 m², or if it contains sleeping accommodation. This tool does not check building regulations. Confirm everything with your local planning authority, and consider a Lawful Development Certificate for proof.