What is prior approval, and how is it different from planning permission?
Prior approval is a narrow council check on named aspects of a project that is otherwise permitted development — usually impact on neighbouring amenity, transport or flooding. The council cannot refuse on grounds outside that list, but within it, refusal is common.
Prior approval in one paragraph
Prior approval is a narrow council check on named aspects of a project that is otherwise permitted development — usually impact on neighbouring amenity, transport or flooding. The council cannot refuse on grounds outside that list, but within it, refusal is common.
Legal basis: Town and Country Planning (General Permitted Development) (England) Order 2015, Schedule 2, Part 1, Class A.4 (the neighbour consultation scheme for larger householder extensions).
What the London numbers show
These are government figures for all 33 London boroughs, not estimates. They are the same numbers we publish on each borough page, summed — so if a borough page and this page ever disagreed, one of them would be wrong.
Larger householder extensions across London
Prior-approval outcomes for extensions beyond the ordinary limits, 2024 Q2 to 2026 Q1.
| Went ahead — prior approval not requiredNo neighbour objected, so no council decision was needed | 6,133 |
|---|---|
| Granted after assessment | 1,224 |
| Refused after assessment | 2,328 |
| Granted where a decision was neededOnce a neighbour objects, refusal is the more likely outcome in London | 34% |
Source: Ministry of Housing, Communities and Local Government (PS1 district planning application statistics). Open Government Licence v3.0 Extracted 2026-08-16.
The larger householder extension route
A single-storey rear extension beyond the ordinary three-metre limit — up to six metres on an attached house, eight on a detached one — is possible without full planning permission, but only through prior approval. You notify the council with a plan and a description; the council writes to the adjoining owners; and if any of them object within the consultation period, the council must decide whether the effect on their amenity is acceptable.
The critical point is that a neighbour objection does not end the project, and the absence of one means the extension proceeds without a decision at all. The council's discretion is engaged only by objection, and only on amenity.
What the council may not consider
Design, materials, and whether officers think the extension is attractive are all outside the scope. So is the loss of your neighbour's view, which is not a planning consideration in any application. The grounds are the impact on the amenity of adjoining premises — daylight, outlook, overbearing effect — and nothing wider.
Why so many prior approvals are refused in London
London's density is the whole answer. A six-metre rear extension on a plot where the neighbour's habitable room window and rear garden sit close to the boundary produces exactly the daylight and overbearing effects the amenity test exists to catch. The tighter the plot, the more likely an objection succeeds.
Which is why the route is worth testing before committing to it: a scheme designed to the ordinary three-metre limit needs no decision at all, and on a constrained plot that certainty is often worth more than the extra depth.
Prior approval: common questions
How long does prior approval take?+
Can a neighbour block my extension?+
What happens if prior approval is refused?+
Not sure how prior approval applies to your property?
Send us the address and what you want to build. We will tell you which route applies before you spend anything on drawings.