What is prior approval for a larger home extension?
Prior approval for a larger home extension is an English scheme that lets you build a single-storey rear extension of up to 6 m (8 m for a detached house) without a full planning application. The council notifies your neighbours, considers only the impact on their amenity, and must decide within 42 days. The fee is £249 from 1 April 2026.
How does the scheme work?
You send the council a description of the extension, a plan, its depth, height and eaves height, and the addresses of adjoining properties. The council notifies those neighbours, who have 21 days to comment. If anyone objects, the council judges whether the extension would harm their living conditions, mainly through loss of light, overshadowing and overbearing impact.
What are the limits?
- Single storey only, at the rear.
- Up to 6 m beyond the original rear wall for attached houses, 8 m for detached houses.
- No more than 4 m high, and eaves no higher than 3 m within 2 m of a boundary.
- Not available in conservation areas, national parks, National Landscapes, the Broads, World Heritage Sites or Sites of Special Scientific Interest.
- The other permitted development conditions still apply, including the 50% coverage limit and matching materials.
How long does it take?
The council has 42 days from a valid submission to decide. If it does not issue a decision in that time, the extension can go ahead, but we always recommend keeping the paperwork and building exactly as described.
Is prior approval better than full planning?
It is cheaper and narrower: the council looks only at the impact on neighbours, not design. If your neighbours are likely to object, or the design is unusual, a full householder application may give a more certain result. We advise on the best route for your house.
Do I still need building regulations approval?
Yes. Prior approval deals only with planning. The extension still needs building regulations approval, and party wall notices if they apply.
This guide is general information, not legal or professional advice for your property. Rules can change; we check the current position for your address at the survey.