The size limits for building a garage without planning permission in England are defined by the Class E permitted development rules for outbuildings. Getting the dimensions right before building avoids the need for retrospective planning permission.

Height Limits

A garage built under permitted development must be single storey. The maximum eaves height (the measurement to the underside of the roof overhang) is 2.5 metres. The maximum overall height is 4 metres for a building with a dual-pitched roof, or 3 metres for any other roof type including flat and mono-pitched roofs. If the garage is within 2 metres of a property boundary, the maximum overall height is reduced to 2.5 metres for any roof type.

Footprint Limits

There is no specific maximum footprint size expressed in square metres for a single outbuilding under Class E, but a cumulative limit applies: the total area covered by all outbuildings and extensions to the original house must not exceed 50 percent of the total curtilage area, excluding the original house footprint. For a typical suburban semi-detached or terraced house with a garden of 80 to 120 square metres, this means the maximum total outbuilding area is 40 to 60 square metres.

In practical terms, a double garage of approximately 6m x 6m (36 square metres) would typically be within the 50 percent limit for most UK gardens, though this must be confirmed for the specific property.

Position Restrictions

The garage must be within the curtilage of the dwelling and must not be forward of the principal elevation, meaning it cannot be placed in the front garden visible from the street. It must be used for purposes incidental to the enjoyment of the house and not as a separate dwelling or business premises.

Exceptions

Listed buildings require planning permission for any outbuilding regardless of size. Some conservation areas and Article 4 Direction areas have had outbuilding permitted development rights removed or restricted. Flats and maisonettes have no outbuilding permitted development rights. Always confirm the position for the specific property and area before building.

Summary

Maximum height is 4m (dual pitch) or 3m (other roof), reduced to 2.5m if within 2m of the boundary. Single storey only. Maximum total outbuilding coverage is 50 percent of the curtilage. Not in the front garden. Listed buildings, some conservation areas, and flats require planning permission regardless of size. Consider a Lawful Development Certificate for garages near the size limits.