Garden rooms, home offices, gyms, workshops and summer houses are among the most popular projects we build. Most can be built without planning permission, as "outbuildings" under permitted development, as long as they stay within some clear limits on height, position and size. Here they are.

How tall can a garden room be without planning permission?

2.5mmaximum height if any part is within 2m of a boundary
4mmaximum height elsewhere with a dual-pitched roof
3mmaximum height elsewhere with any other roof
2.5mmaximum eaves height in all cases
Height limits for garden rooms and outbuildings Three outbuildings. One within 2 metres of the boundary is limited to 2.5 metres high. One elsewhere with a dual-pitched roof can be 4 metres high with eaves of 2.5 metres. One elsewhere with a flat or mono-pitch roof can be 3 metres high. Boundary 2m 2.5m Within 2m max 2.5m high 4m eaves 2.5m Dual-pitched roof 3m Other roof
Elevation, not to scale. All outbuildings must also be single storey, behind the front of the house, and within the 50% coverage limit.

What are all the permitted development limits?

RuleLimit
PositionNot on land forward of the wall forming the front (principal elevation) of the house.
StoreysSingle storey only.
Height2.5m within 2m of a boundary. Elsewhere 4m with a dual-pitched roof, or 3m with any other roof. Eaves no higher than 2.5m.
CoverageNo more than half the land around the original house can be covered by additions and other buildings.
Verandas and deckingNo verandas, balconies or raised platforms; any platform no more than 0.3m high.
UseMust be incidental to the house (office, gym, studio, playroom, storage), not separate self-contained accommodation.

The same outbuilding rules cover sheds, greenhouses, garages, saunas, kennels and even swimming pools and ponds. See do I need planning permission for a swimming pool?

Can I sleep in a garden room or use it as an annexe?

Usually permitted development

  • Home office or studio
  • Gym or games room
  • Hobby room or workshop
  • Garden storage

Needs planning permission

  • A self-contained annexe with its own bedroom, kitchen and bathroom
  • Any other separate, self-contained living accommodation

Where are the rules stricter?

  • Listed buildings: any outbuilding within the curtilage of a listed building needs planning permission.
  • Conservation areas and the Cotswolds National Landscape: outbuildings, enclosures and pools at the side of the house need planning permission.
  • National Landscapes, National Parks, the Broads and World Heritage Sites: buildings, enclosures and pools more than 20m from the house are limited to 10m² in total.
  • Flats and maisonettes: these permitted development rights do not apply.
  • Article 4 directions or planning conditions can remove the rights altogether.
In the Cotswolds?Read extending a home in the Cotswolds or a conservation area for how the rules change on Article 2(3) land.

What base does a garden room need?

A garden room is only as good as what it stands on. A level, properly drained base stops doors sticking, floors bouncing and damp creeping in. Depending on the building and the ground, that might be a concrete slab, a pad or ground-screw system, or full foundations for a heavier masonry building.

  1. Check the positionConfirm the building is behind the front of the house, within the height limits for its distance from the boundary, and within the 50% coverage limit.
  2. Plan servicesRun ducts for electricity and data before the base goes down.
  3. Build the baseExcavate, lay a compacted sub-base and form a level slab or pad base, with drainage away from the building.
  4. Build the roomTimber frame, masonry or modular, finished to match how you will use it.
Building regulationsDepending on its size, construction and use, a garden room may also need building regulations approval, separately from planning. Check with building control or your builder at the design stage.

What we build: garden rooms, garden offices, summer houses, barns, garages and pergolas, from the base up, so the building and what it stands on are built by one team.