Do I Need Planning Permission for a Rear Extension?

Most rear extensions in England do not need planning permission. Under permitted development rights, homeowners can extend the rear of their property without submitting a planning application — as long as the extension stays within certain size and height limits. Deeper extensions may still be possible via prior approval, which is a different process from standard permitted development.

• Extends no more than 3 metres from the original rear wall on semi-detached or terraced houses
• Extends no more than 4 metres from the original rear wall on detached houses
• Maximum height does not exceed 4 metres
• Eaves height does not exceed 3 metres if the extension is within 2 metres of a boundary
• Total area of additions (including the extension) does not cover more than half the curtilage
• Materials are similar in appearance to the existing house

Depths beyond these standard limits — up to 6 metres on semi-detached or terraced houses, and up to 8 metres on detached houses — are not standard permitted development. They require prior approval under the Larger Home Extension scheme (see below).

• Extends no more than 3 metres from the original rear wall
• No closer than 7 metres to the rear boundary
• Roof pitch matches the existing house
• Any upper-floor window in a side elevation is obscure-glazed and non-opening below 1.7 metres from floor level

• Property is a flat or maisonette
• Property is a listed building
• Extension exceeds the standard size limits above, and either exceeds the larger-home prior-approval depths or is on designated land where that scheme does not apply
• Permitted development rights removed by Article 4 direction
• Original planning permission conditions restrict PD rights

Single-storey rear extensions between 3 and 6 metres (semi-detached or terraced) or between 4 and 8 metres (detached) are not automatic permitted development. They need prior approval under the Larger Home Extension neighbour consultation scheme: you notify the council, neighbours are consulted for 21 days, and there is a fee of around £103. This is not full planning permission, but it is not the same as standard permitted development either — you must get prior approval (or wait out the process without objection) before starting work.

The Larger Home Extension scheme does not apply on designated land, including conservation areas, National Parks, Areas of Outstanding Natural Beauty (National Landscapes), and World Heritage Sites. On designated land, anything beyond the standard 3 metre / 4 metre depths needs a full planning application.

In conservation areas and other designated land, permitted development rights are more restricted, and the Larger Home Extension prior-approval route is not available. Listed buildings always require listed building consent regardless of size.

Planning permission and building regulations are separate. A rear extension almost always needs building regulations approval for structure, insulation, drainage, electrics and fire safety — even when the work is permitted development or has prior approval.

Planning rules change and can vary by location. Dimensions, property type, designated land status and previous extensions all affect whether you need permission. Confirm with your local planning authority, or use our free checker for a tailored answer for your specific project.