The government has made permanent the scheme for larger household extensions.

The prior approval application

If you want to add a large rear extension to your home, you may be able to do so, but will need to apply for prior approval before carrying out any work. This will involve us asking the views of your neighbours.

What sort of extension you can build

  • A single-storey rear extension between three and six metres deep for terraced or semi-detached homes, with three metres maximum eaves height and four metres maximum ridge height
  • A single-storey rear extension between four and eight metres deep for detached homes, with three metres maximum eaves height and four metres maximum ridge height

The measurement is taken from the original rear wall of the property.

The prior approval process

You will need to apply to us for prior approval. You can do so using the notification of a proposed larger extension form on the neighbour consultation scheme page on the Planning Portal. You should also provide a plan showing your house, your boundaries and the proposed footprint of the extension. The plan does not have to be drawn to scale. The submission should indicate the measurements of the proposal and if you are using a plan with Ordnance Survey Data, it must include a valid Ordnance Survey licence number.

The fee for this type of application is £96.

Once we have received a valid prior approval application, we will, as required, consult your adjoining neighbours by letter. If they respond, we may ask you for proposed plans so we can fully assess the proposal and will consider their comments if they have any planning merit.  We then decide if the proposal can go ahead in the form submitted.  If we do not receive any comments within 21 days, the proposal is deemed permitted development and does not need further planning permission. 

The application process should take no longer than 42 days from the date the application is valid.


Properties that are within a conservation area, statutorily listed buildings, and properties which have had permitted development rights removed by condition or through an Article 4 Direction (such as that affecting the Wellesley development) are excluded from this scheme. You will need to seek planning permission for any such proposal.   

If you need more advice about this, or any other type of extension to your home, you can enter into a pre-application advice discussion with us. This is a chargeable service and the fee for a householder enquiry starts at £70.

Building regulations

If you want to build an extension, you may need building regulations. You can find out more on our do I need building control permission? page.

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