It is possible to build some larger single-storey rear extensions under permitted development. The size limits are  8 metres for detached houses, and 6 metres for all other houses. 

If your property is within a Conservation Area then you would need to submit a Householder application.

No development shall start until you receive written notification from us that either:

  • prior approval is not required;
  • prior approval is required and given;
  • or the expiry of a period of not less than 42 days following the date on which the information was received by us and no written notification has been sent to the developer as to whether prior approval is given or refused.

Before making an application:

If you are still unsure then you can submit a Householder Development Enquiry to establish what permissions may be required.


You can submit your application by downloading and completing an application form and sending it to us. You will need to supply your address then select the form Prior Approval: Larger Home Extension


You can also download help text and guidance notes to assist in completing the application form..


The fee for a notification of a proposed larger home extension is £96. Visit the paying your planning fees page for more information on how to pay your fees or if an exemption applies.

What happens next?

We will serve a notice on adjoining owners or occupiers, i.e. those who share a boundary, including to the rear. This will give the address of the proposed development and describe it, including the information above. It will also set out:

  • When the application was received, and when the 42-day determination period ends
  • How long neighbours have to make objections (which must be a minimum of 21 days), and the date by which these must be received

A copy of this notice must also be sent to the developer.

If any adjoining neighbour raises an objection within the 21-day period, the local authority will take this into account and make a decision about whether the impact on the amenity of all adjoining properties is acceptable.

No other issues will be considered.


The development can go ahead if the local authority notifies the developer in writing either:

  1. That as no objections were received from adjoining neighbours it has not been necessary to consider the impact on amenity, or
  2. That following consideration, it has decided that the effect on the amenity of adjoining properties is acceptable.
    • If we do not notify the developer of our decision within the 42-day determination period, the development may go ahead.
    • If approval is refused, the developer may appeal.
    • The extension must be built in accordance with the details approved by us (or, if no objections were raised or we have not notified the developer of its decision, the details submitted), unless we agree any changes in writing.
    • The development must accord with all other relevant limitations and conditions which apply to other rear extensions allowed under permitted development. These are set out in Class A, and include for example, the requirement that the extension (apart from a conservatory) must be constructed using materials of a similar appearance to those used in the construction of the rest of the house.