Conservatories

The ‘prior approval’ process only applies to larger single-storey rear extensions.

This is defined as extending beyond the rear wall of the original house* by:

• over four and up to eight metres for detached houses; and
• over three and up to six metres for all other houses

If you wish to build an extension of this size, you must apply to the local authority, who will then consult the adjoining neighbours to advise them of your proposals.

If your neighbours raise any concerns or objections, the local authority will be required to determine if the proposal’s impact on the amenity of all adjoining properties is acceptable and, based on this, whether it can go ahead.

Read about how your extension may affect your neighbours¹.

Prior Approval: Larger Home Extension

A householder can apply online to the local planning authority when they intend to build a larger single-storey rear extension, as described above.

Please read our guidance note for further information about the process².

Additional detailed government guidance is avaliable.³

Definitions

Original house

Also known as the ‘original dwellinghouse’. This 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.

1. https://www.planningportal.co.uk/permission/responsibilities/planning-permission/factors-affecting-planning-permission-your-neighbours
2. https://ecab.planningportal.co.uk/uploads/1app/guidance/guidance_note-larger_home_extension.pdf
3. https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/830643/190910_Tech_Guide_for_publishing.pdf