Larger home extension prior approval in London: the 6m and 8m neighbour consultation route

Many London houses can already add a modest single-storey rear extension under ordinary permitted development. The larger home extension scheme goes further: it lets you build a deeper single-storey rear extension without a full householder planning application, provided you go through prior approval and a neighbour consultation first. The right is set out in Class A of the Town and Country Planning (General Permitted Development) (England) Order 2015, and the government explains it in the GOV.UK permitted development technical guidance and on the Planning Portal prior approval page for extensions.

What counts as a larger home extension?

Under the neighbour consultation scheme, a larger single-storey rear extension is one that extends beyond the rear wall of the original house by:

• more than 3 metres and up to 6 metres for a terraced or semi-detached house; or
• more than 4 metres and up to 8 metres for a detached house.

Extensions within the ordinary 3m / 4m limits do not need this prior approval process. Anything deeper than 6m / 8m, or anything that fails the other Class A limits, needs a full planning application instead. "Original" means the house as first built, or as it stood on 1 July 1948 if older — earlier extensions by previous owners count towards the depth you have left.

Limits that still apply

Prior approval does not waive the rest of Class A. In particular:

• the extension must be single storey and no more than 4 metres high;
• where any part is within 2 metres of a boundary, eaves height must not exceed 3 metres;
• together with other buildings, development must not cover more than half the curtilage around the original house;
• materials should be of similar appearance to the existing house;
• verandas, balconies and raised platforms (over 0.3 metres) are not permitted development under Class A.

Our guide to permitted development for house extensions in London covers the ordinary limits in more detail.

Where the route is not available in London

The larger home extension neighbour consultation scheme is not available on article 2(3) land, which includes conservation areas, or on a site of special scientific interest. In those places the ordinary rear depth caps (3m / 4m) still apply where PD is available at all, and many deeper schemes need full planning permission. The scheme also does not apply to flats or maisonettes, listed buildings needing listed building consent for the works, or houses where permitted development rights have been removed by an Article 4 direction or a condition on an earlier permission. Always check your borough's conservation area map and Article 4 list before relying on this route — especially in areas such as Islington, Camden, Kensington & Chelsea and Hammersmith & Fulham, where designated land is common.

How the prior approval process works

1. Notify the council before you start, usually online via the Planning Portal as a "Prior Approval: Larger Home Extension" application, with a written description of the proposal, plans showing the site and the proposed extension, and the addresses of adjoining premises.
2. Neighbour consultation: the council must notify adjoining owners and occupiers (those who share a boundary, including to the rear) and give them at least 21 days to object on amenity grounds such as light, outlook and overbearing impact.
3. Decision: if nobody objects, the council confirms that prior approval is not required. If there is an objection, the council must decide whether the impact on the amenity of adjoining properties is acceptable. The determination period is 42 days from a valid submission. If the council does not notify you of a decision within that period, you may proceed — but get written confirmation of the deemed approval before you dig.

You must not start work until the council has written that prior approval is not required, or has given prior approval, or the 42 days have passed without a decision. The process cannot be used retrospectively: building first and notifying later is not lawful permitted development.

Fees from 1 April 2026

From 1 April 2026, the statutory fee in England for a prior approval application for a larger rear extension or other alteration of a dwellinghouse under Part 1 Class A is £249, according to the government's published planning fees indexation schedule from 1 April 2026 and the Planning Portal's English application fees guide. A full householder planning application is a separate, higher fee. Confirm the current figure on the Planning Portal fee calculator before you pay, because fees are indexed each April.

Planning is not building regulations or party walls

Even if prior approval is granted or not required, you still need building regulations approval for the extension, and you may need to serve a Party Wall notice if you cut into a shared wall or excavate near a neighbour. See our guides to building regulations sign-off and the Party Wall Act. A Lawful Development Certificate is still worth considering once the scheme is lawful, because buyers and lenders often ask for it.

Budget and next steps

For indicative 2026 build-cost ranges, see our London house extension cost guide. When you are ready to compare builders, use our quote form — Home Builders does not carry out building work; we ask advertisers to provide proof of insurance before they are listed, and any contract is between you and the builder you choose.

Sources: GOV.UK: Permitted development rights for householders, technical guidance; Planning Portal prior approval for extensions; MHCLG planning fees from 1 April 2026; Planning Portal English application fees. This guide is a summary, not legal advice; confirm details with your council or a planning professional.

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