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Larger home extension prior approval, step by step

The larger home extension route lets a single-storey rear extension go up to 8 m beyond the rear wall of the original house if it is detached, or 6 m for any other house, no higher than 4 m, provided you notify the council before you start and follow the process in para A.4 (SI 2015/596 Sch 2 Pt 1 para A.1(g)). It is not available on article 2(3) land, which includes conservation areas, or on a Site of Special Scientific Interest. The council fee is £249.

Free. England only. Next you tap your home on the map, so we test your plot outline, not the postcode.

Does your project fit?

  • Single storey, more than 3 m (4 m detached) beyond the rear wall of the original house but no more than 6 m (8 m detached), and no higher than 4 m (A.1(f), (g)).
  • The house is not on article 2(3) land or a Site of Special Scientific Interest (A.1(g)). Article 2(3) land includes conservation areas, National Parks, National Landscapes, the Broads and World Heritage Sites (Sch 1 Pt 1).
  • Every other Class A limit still applies: the 50% garden rule, no higher than the existing roof, eaves no higher than the existing eaves, eaves no higher than 3 m within 2 m of a boundary, nothing beyond the principal elevation or a side wall facing a highway, totals with any joined extension, no balconies or raised platforms, and matching materials (A.1(b) to (k), A.3). See single-storey rear extensions.

The process

  1. Send the council the information before you start (A.4(2)): a written description of the extension, including how far it goes beyond the rear wall of the original house, its maximum height and its eaves height (as totals if it joins an existing extension); a plan showing the site, the extension and any existing extension it joins; the addresses of adjoining premises; your contact address; and your email address if you are content to receive messages that way. Include the fee.
  2. Pay the fee. From 1 April 2026 it is £249. If you apply online through the Planning Portal, its service charge band for householder prior approval is Band 1, £99 including VAT (Planning Portal service charges).
  3. The council checks the details. It may refuse if the extension does not comply with the Class A limits, or if you have not given enough information to show it does (A.4(3)). Such a refusal is treated as a refusal of approval for appeal purposes under section 78 (A.4(4)).
  4. Neighbours are notified. The council serves a notice on each adjoining owner or occupier, describing the extension and giving a date, at least 21 days from the notice, by which comments must arrive; you get a copy (A.4(5), (6)). Public holidays do not count towards the 21 days (A.4(16)). An "adjoining owner or occupier" is any owner or occupier of premises or land adjoining the site (art 2(1)).
  5. If a neighbour objects, the council's prior approval is needed on the impact on the amenity of adjoining premises (A.4(7)). It must take account of the comments and consider the amenity of all adjoining premises, not only those that commented (A.4(9)). It may ask you for more information (A.4(8)), and may give prior approval with or without conditions about that impact (A.4(12)).
  6. When you may start (A.4(10)): once you receive written notice that prior approval is not required, or written notice giving prior approval, or once 42 days have passed from the date the council received your information without it telling you whether prior approval is given or refused.
  7. Build what you notified. Where prior approval was needed, the work must follow the details the council gave approval for; otherwise it must follow the information you sent, unless you and the council agree otherwise in writing (A.4(11)).

Article 4 directions made later

An Article 4 direction does not affect development subject to prior approval where the prior approval date came before the direction came into force and the work is completed within 3 years of that date (art 4(2)(a)). See our Article 4 check.

On article 2(3) land or an SSSI

Here the options are a single-storey rear extension within 3 m (4 m detached) under Class A, or a planning application, at a council fee of £548 for one house. See our conservation area check.

A February 2024 government consultation proposed changes to householder rights, but GOV.UK still says "We are analysing your feedback", so the current limits stand.

What the free check tells you

The free check tests your plot outline against conservation areas, National Parks, National Landscapes, the Broads, World Heritage Sites and SSSIs, so it shows whether the larger home extension route is open on the data we hold, and the depth that applies to your house type. Where a council does not publish its conservation area data, the route is shown as not confirmed unless you tell us what the council's own map shows.

For certainty: a Lawful Development Certificate

The prior approval process deals with the larger depth and the neighbours' amenity. For certainty on the rest of the Class A rules, you can also apply to your council for a Lawful Development Certificate for proposed works (TCPA 1990 s192), at a council fee of £274, with a decision due within 8 weeks of a valid application. See Lawful Development Certificates and planning fees 2026.