What is prior approval in planning?

Prior approval is a lighter-touch planning process that sits between full permitted development and a formal planning application. For certain types of development - most commonly larger single-storey rear extensions - you must notify the local planning authority and allow them to consider the impact on neighbouring properties before the work can proceed, even though full planning permission is not required.

When is prior approval needed for a rear extension?

Prior approval is required for single-storey rear extensions that exceed the standard permitted development size limits but fall within the larger home extension scheme. This allows extensions up to 8m deep on a detached house (or 6m on any other house) subject to prior approval. Extensions within the standard limits (4m detached, 3m other) do not need prior approval.

How long does prior approval take?

The local planning authority has 42 days from receipt of a valid prior approval application to notify you of their decision. If they do not respond within 42 days, the development is automatically deemed approved and can proceed. In practice most authorities respond within the 42 days - adjoining neighbours are consulted and given 21 days to make representations.

What can the council assess in a prior approval application?

For the larger home extension scheme, the council can only consider the impact of the proposed extension on the amenity of adjoining properties - specifically overlooking, loss of light, and overshadowing. They cannot refuse on general planning grounds such as design or character. If no objection is received from neighbours, the authority must grant approval.

Prior Approval - Construction Glossary

Definition

Prior approval is a lighter-touch planning process that sits between full permitted development and a formal planning application. For certain categories of development - most commonly larger single-storey rear extensions - the applicant must notify the local planning authority (LPA) before starting work, allowing neighbours to comment and the LPA to assess specific limited impacts. It is not a full planning application and the council's assessment is restricted to defined matters.

In practice

The most common domestic use of prior approval is the larger home extension scheme, which allows single-storey rear extensions beyond the standard permitted development size limits - up to 8m deep on a detached house and 6m on any other house. To use this scheme, a prior approval application must be submitted before work starts. The LPA notifies adjoining owners, who have 21 days to make representations.

The LPA has 42 days from receipt to give a decision. If they do not respond within 42 days, development is automatically deemed approved. Importantly, the council can only consider the impact on the amenity of adjoining properties - not general planning matters such as design or character. If no neighbour objects, the authority must grant approval. Prior approval for the larger extension scheme applies until 2026 under current regulations.

Planning & Regulations

LegislationGPDO 2015 Schedule 2 Part 1 Class A

Max depth (detached)8 m single-storey rear extension

Max depth (other houses)6 m single-storey rear extension

LPA decision period42 days - deemed approved if no decision

Prior approval does not remove the requirement for Building Regulations approval - the extension will still need to comply with the relevant Approved Documents and be signed off by Building Control. Works must not start before prior approval is granted (or the 42-day period has elapsed without a decision). Prior approval is not available on listed buildings or in certain other restricted cases.

Full planning permission guidance

Prior Approval

Just so you know...