Do I need planning permission? A guide for London homeowners

Houses and flats are treated differently

Permitted development rights for extensions and loft conversions apply to houses. Flats and maisonettes do not have these householder rights, so most external changes to a flat need a planning application.

Rear extensions

A single-storey rear extension on a house can be permitted development if it stays within set limits, including a depth of up to 3 metres for an attached house or 4 metres for a detached house.

Larger single-storey rear extensions (up to 6 metres attached, 8 metres detached) may be possible through the prior approval process, where neighbours are notified before the council decides.

Loft conversions

A loft conversion on a house can be permitted development within volume limits of 40 cubic metres for terraced houses and 50 cubic metres for detached and semi-detached houses, along with other conditions.

Roof extensions in conservation areas are not permitted development, and extensions facing the road usually need permission.

Conservation areas, listed buildings and Article 4

Many London streets are in conservation areas or are covered by Article 4 directions, which remove some permitted development rights. Listed buildings need listed building consent for most works.

Check the council's planning maps for your address, or ask us to check before you plan the design.

Getting certainty

If you believe the work is permitted development, a Lawful Development Certificate from the council confirms it in writing. This is useful when you later sell the property.

Where permission is needed, councils aim to decide most householder applications within 8 weeks of validation.