Extensions

Planning Permission

The increased size limits for single-storey rear extensions that were previously time limited and due to expire on 30 May 2019 have now been made permanent by government. 
Read the legislation

Any such proposals will still be subject to the associated neighbour consultation scheme. This requires that the relevant Local Planning Authority is informed of the proposed work via a prior approval application.

An extension or addition to your house is considered to be permitted development, not requiring an application for planning permission, subject to the following limits and conditions:

  • No more than half the area of land around the "original house"* would be covered by additions or other buildings
  • No extension forward of the principal elevation or side elevation fronting a highway
  • No extension to be higher than the highest part of the roof
  • Single-storey rear extensions must not extend beyond the rear wall of the original house* by more than eight metres if a detached house; or more than six metres for any other house
    If the house is in Article 2(3) designated land* or a Site of Special Scientific Interest, this limit is reduced to four metres if a detached house; or three metres for any other house
    These limits are now permanent and subject to the neighbour consultation scheme. This requires that the relevant Local Planning Authority is informed of the proposed work via a prior approval application
  • Maximum height of a single-storey rear extension of four metres
  • Extensions of more than one storey must not extend beyond the rear wall of the original house* by more than three metres
  • Maximum eaves height of an extension within two metres of the boundary of three metres
  • Maximum eaves and ridge height of extension no higher than existing house
  • Side extensions to be single storey with maximum height of four metres and width no more than half that of the original house
  • Two-storey extensions no closer than seven metres to rear boundary
  • Roof pitch of extensions higher than one storey to match existing house
  • Materials to be similar in appearance to the existing house
  • No verandas, balconies or raised platforms
  • Upper-floor, side-facing windows to be obscure-glazed; any opening to be 1.7m above the floor
  • On Article 2(3) designated land* no permitted development for rear extensions of more than one storey
  • On Article 2(3) designated land* no cladding of the exterior
  • On Article 2(3) designated land* no side extensions.

* The term "original house" means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date). Although you may not have built an extension to the house, a previous owner may have done so.

* Article 2(3) designated land is land within:

  • a conservation area; or
  • an area of outstanding natural beauty; or
  • an area specified by the Secretary of State for the purposes of enhancement and protection of the natural beauty and amenity of the countryside; or
  • the Broads; or
  • a National Park; or
  • a World Heritage Site.

Please note: The permitted development allowances described here apply to houses and not to:

Installation, alteration or replacement of a chimney, flue or soil and vent pipe: Read guidance on the permitted development regime under Class G of the regime.

Please be aware that if your development is over 100 square metres, it may be liable for a charge under the Community Infrastructure Levy.

Permitted Development for householders – Technical Guidance

You are strongly advised to read a technical guidance document produced by the Government to help understand how permitted development rules might apply to your circumstances.

View 'Permitted development for householders – Technical guidance' on Gov.uk