Permitted development for house extensions in London: what you can build without planning permission

Permitted development (PD) rights allow some householder extensions to go ahead without a full planning application. They are set nationally in the Town and Country Planning (General Permitted Development) (England) Order 2015, Schedule 2, Part 1, and they apply in every London borough unless they have been removed or restricted for a particular property or area.

Who has permitted development rights?

PD rights for extensions apply to houses. They do not apply to flats or maisonettes, so if you own a converted flat in, say, a Victorian terrace, almost any extension will need planning permission. Rights can also have been removed by a condition on an earlier planning permission, or by an Article 4 direction made by the council.

Single-storey rear extensions: the headline limits

• Depth beyond the original rear wall: up to 3 metres for a terraced or semi-detached house and 4 metres for a detached house.
• Maximum height of 4 metres; where the extension is within 2 metres of a boundary, eaves height must not exceed 3 metres.
• Together with other buildings, the extension must not cover more than half of the land around the original house.
• Materials should be similar in appearance to the existing house.

"Original" means the house as it was first built or as it stood on 1 July 1948. Earlier extensions by previous owners count towards the limits.

Larger home extensions and prior approval

A larger single-storey rear extension, up to 6 metres (attached houses) or 8 metres (detached), may be possible under the prior approval route. You notify the council, neighbours are consulted, and the council considers the impact on their amenity. You must not start work until prior approval is given or the determination period passes without a decision. This route is not available on designated land such as conservation areas.

Side extensions and two-storey extensions

Single-storey side extensions are limited to 4 metres in height and no more than half the width of the original house. Extensions of more than one storey have further limits, including a maximum depth of 3 metres and a minimum of 7 metres from the rear boundary. In practice, many two-storey extensions in London need planning permission.

Conservation areas and Article 4 directions

London has a very large number of conservation areas. On this "designated land", side extensions and rear extensions of more than one storey are not permitted development, and cladding the exterior is restricted. Many boroughs also use Article 4 directions to remove specific rights, for example to protect front elevations, windows or roofs. Always check your council's conservation area map and Article 4 list before relying on PD.

Get certainty: the Lawful Development Certificate

You do not have to apply for anything to use PD rights, but a Lawful Development Certificate (LDC) from the council confirms that your scheme is lawful. It is strongly recommended in London, where solicitors and buyers frequently ask for it when you come to sell.

Planning is not the same as building regulations

Even a PD extension needs building regulations approval, and may need a Party Wall notice. See our guides to building regulations sign-off and the Party Wall Act.

Sources: GOV.UK: Permitted development rights for householders, technical guidance; the Planning Portal interactive guides. This guide is a summary, not legal advice; confirm details with your council or a planning professional.

Frequently asked questions