The short answer
It is the prior approval route for larger single-storey rear extensions. You tell the council what you plan, it writes to the adjoining neighbours, and if nobody raises a valid objection about their amenity, or the council does not decide within 42 days, you can build. The fee is £249.
The neighbour consultation scheme, properly called prior approval for a larger home extension, sits between ordinary permitted development and a full planning application. For a London terrace it doubles how far you can build out at the back without applying for planning permission.
What it allows
Under normal permitted development, a single-storey rear extension on a terraced or semi-detached house can project 3 metres beyond the original rear wall. Under this scheme it can project up to 6 metres (8 metres for a detached house). Everything else in the normal rules still applies: one storey, no more than 4 metres high, eaves no higher than 3 metres within 2 metres of a boundary, and materials similar to the house.
“Original” means the house as first built, or as it stood on 1 July 1948. If the outrigger of a Victorian terrace already reaches back 4 metres, it is part of the original house; an earlier 1980s kitchen extension is not.
Where it does not apply
- In conservation areas, national parks and other protected land.
- On flats and maisonettes, which have no householder permitted development rights.
- Where an Article 4 direction has removed rear extension rights.
- Where the borough has removed the rights by a condition on an earlier permission.
Large parts of inner London are in conservation areas, so check the borough’s map first.
How the process runs
- You apply to the council with a written description, a plan showing the extension, its depth, height and eaves height, the addresses of adjoining properties, and the £249 fee.
- The council notifies the neighbours that share a boundary, including those at the back, and gives them 21 days to comment.
- If nobody objects, the council does not assess the impact and the extension can go ahead.
- If a neighbour objects, the council considers only the effect on the amenity of adjoining properties: light, outlook, privacy and overbearing. Design and other planning issues are not in play.
- The council decides within 42 days. If it has not, you can proceed.
Once built, you must tell the council in writing that the work is complete.
Is it worth it on a terrace?
Six metres is a long extension on a narrow plot, and it can leave the middle room of the house dark. Many London owners use the scheme for 4 to 5 metres, enough for a kitchen and dining table across the full width, with a run of roof glazing to keep light in.
Prior approval is not a lawful development certificate. It confirms the council does not object to the impact; it does not check every other permitted development condition. For a factory-built extension, where the size is fixed before the lift, make sure the drawings meet every limit.
To see what a 5 or 6 metre extension might cost, start with our guide to modular extensions London homes can take, then run the size through the cost calculator.