Prior Approval for Larger Home Extensions: The Neighbour Consultation Scheme Explained

Under Class A of Part 1 of Schedule 2 to the Town and Country Planning (General Permitted Development) (England) Order 2015 (the GPDO), a householder can extend a single-storey rear extension beyond the standard depth limits under permitted development without a full planning application, subject to: Maximum depth: 8 metres for a detached house, 6 metres for any other house (semi-detached, mid-terrace, end-of-terrace). Maximum height: 4 metres (measured from the highest point of the roof of the extension, including the ridge of any pitched roof). All other Class A conditions: The extension cannot exceed the permitted development limits for maximum eaves height (3m if within 2m of a boundary, otherwise no higher than the eaves height of the existing house), cannot be forward of the principal elevation or side elevation fronting a highway, cannot exceed 50% of the original curtilage area when combined with all other extensions and outbuildings, and must use materials that are of similar appearance to those of the exterior of the existing house. The prior approval right does not apply to: Listed buildings or scheduled monuments. Land within the curtilage of a listed building. Article 2(3) land — conservation areas, Areas of Outstanding Natural Beauty, National Parks, the Broads, and World Heritage Sites. Land designated as a Site of Special Scientific Interest. Properties where the PD right has been removed by a planning condition or Article 4 Direction.

Before starting construction of a larger extension under the prior approval route, the homeowner must submit a prior approval notification to the local planning authority. The notification must include: The name and address of the applicant; a site plan and proposed floor plan and elevations (not required to be to the full standard of a planning application, but must be clear enough to describe the development); details of the proposed materials to be used; a written description of the proposed works. The fee for a prior approval notification is £120 (as of 2025/2026). On receipt of a valid notification, the local planning authority must: Notify the adjoining property owners on both sides of the applicant's house (the properties immediately to the left and right of the application property, and any property immediately behind if the extension reaches or is near the rear boundary) of the proposed development. The notification must invite the adjoining owners to make representations within a 21-day consultation period. If no objections are received within the 21 days, the planning authority can grant prior approval. If objections are received, the planning authority must assess whether the proposed extension would have an unacceptable impact on the amenity of the adjoining premises. The planning authority must determine the notification within 42 days of receipt. If no determination is issued within 42 days, prior approval is deemed to be granted and construction can commence.

The prior approval procedure for larger extensions is fundamentally different from a full planning application in one critical respect: the grounds on which the planning authority can refuse prior approval are very limited. The planning authority can only consider the impact of the proposed extension on the amenity of the adjoining premises. It cannot consider: whether the design is appropriate for the area; the impact on the street scene; the extension's relationship to the principal elevation; general policy considerations about the appropriate scale of development; or any other planning considerations beyond the direct amenity impact on the immediately adjoining properties. The grounds for refusal in practice are: Loss of daylight or sunlight to the adjoining property (particularly relevant for extensions that extend significantly beyond the neighbour's rear wall, shading their garden); loss of outlook (where the extension creates an overbearing presence when viewed from the adjoining property's windows or garden); loss of privacy (where windows in the extension directly overlook the neighbour's garden or habitable rooms). If a neighbour objects but the planning officer concludes that the impact on amenity is not unacceptable, prior approval must be granted — the neighbour's objection alone is not a sufficient ground for refusal. If the planning authority refuses prior approval, the applicant has the right of appeal to the Planning Inspectorate. Alternatively, a full planning application can be submitted.

The prior approval route for larger extensions can be used strategically where a homeowner wants to extend beyond the standard PD limits and has a good relationship with their immediate neighbours, or where the extension is on a plot where the adjoining property's windows and amenity spaces are not adversely affected. Practical tips: Have the conversation with your immediate neighbours before submitting the notification — if they are supportive, they can confirm this to the planning authority during the consultation period, making a smooth outcome more likely. Ensure the proposed extension complies with all the Class A conditions before submitting the notification — the planning authority will check these and can reject the notification if the development does not comply (for example, if the proposed materials are inappropriate). Consider the 45-degree test informally as a guide to daylight impact on neighbours — if the extension would cut significantly across the 45-degree line from the centre of the neighbour's nearest ground floor habitable room window, daylight impact is more likely to be a concern. Note the 42-day deemed approval provision — if the local planning authority fails to determine the notification within 42 days, the prior approval is automatically granted. Keep evidence of the submission date and the 42-day expiry. This provision is occasionally useful where a planning authority is experiencing processing backlogs.