Do you need planning permission for a garden room?

The short answer

A garden office, gym or studio can often be built without planning permission, under what's called permitted development. Whether yours can depends on four things: the property, where the room sits, its dimensions and what you plan to use it for.

The rules below apply to houses in England. Wales, Scotland and Northern Ireland have their own.

What permitted development allows

Permitted development lets you put up an outbuilding in your garden without applying for planning permission, as long as it stays within set limits. The main ones, from the government's Planning Portal, are:

• A single storey, with eaves no higher than 2.5m
• An overall height of no more than 4m with a dual pitched roof, or 3m for any other roof
• A maximum height of 2.5m if any part of the building is within 2m of a boundary
• Nothing on land in front of the main face of the house
• No more than half the land around the original house covered by extensions and other buildings
• No verandas, balconies or raised platforms over 0.3m high
• Not used as separate, self-contained living accommodation

The height rule near boundaries is the one that shapes most of our designs. Gardens in London are rarely wide, so the room usually ends up within 2m of a fence. When we design under permitted development, we keep the whole building within 2.5m externally if any part of it is that close.

When you will need planning permission

Flats and maisonettes. Permitted development for outbuildings applies to houses, not flats. We've built projects for flats that needed planning permission for exactly this reason.

Listed buildings. Any outbuilding within the grounds of a listed building needs planning permission.

Conservation areas. These come with extra restrictions. Outbuildings to the side of a property, for example, need permission. Permitted development can still apply in some circumstances, so it's worth checking your exact position early.

Going over the limits. If the room needs to be taller than the permitted heights, or breaks another of the limits above, it will need permission.

Local restrictions. Some councils remove permitted development rights in certain streets through an Article 4 Direction, and some properties have conditions attached to an earlier planning consent. Either can mean an application is needed.

One thing people often get wrong: going over 30m² generally brings in building regulations, but it doesn't automatically mean you need planning permission. They are separate questions.

Planning permission and building regulations are different

Planning is about whether the building is allowed. Building regulations are about how it's built: structure, fire safety and so on.

For a detached garden room without sleeping accommodation:

• Under 15m²: usually exempt from building regulations
• Between 15m² and 30m²: usually exempt as long as the building is at least 1m from any boundary, or is built substantially from non-combustible materials
• Over 30m²: generally needs building regulations approval

Electrical work has its own requirements whatever the size. Every room we build comes with an electrical certificate.

If you want a bedroom

Sleeping accommodation changes things. A room someone sleeps in is no longer treated like a garden office, for planning or for building regulations. If that's the plan, we check the planning position specifically and involve building control from the start.

What we check when we visit

Every project starts with a free visit to your garden. On planning, we look at:

• where you'd like the room and how close it is to each boundary
• ground levels, which affect the overall height
• the height the room needs to be for how you'll use it
• existing buildings in the garden
• how you intend to use the room
• any planning restrictions on the property itself, such as a listed building, a conservation area or an Article 4 Direction

From that, we can tell you whether the design can stay within permitted development, or whether it's worth applying.

If you do need to apply

We work with a planning consultant who can prepare the drawings and handle the application for you. If you already have your own consultant, that works too.

If you're unsure about your property, your local planning authority can confirm the position. You can also apply for a Lawful Development Certificate, which confirms in writing that a room falls within permitted development. It isn't required, but some people like having it, particularly when they come to sell.

Talk it through with us

The quickest way to find out where you stand is to show us the space. Book a free 30-minute visit and we'll look at the position, the height and the planning side together, then follow up with a 3D visual and a fixed written quote.