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What size extension can I build without planning permission?

In many circumstances, rules known as ‘permitted development’ rights allow you to extend a house without needing to apply for planning permission, providing specific limitations and conditions are met. If you want to exceed these limits and conditions, then it is likely that an application for householder planning permission will be required.

You can find information about the limits and conditions, prior approval and the building regulations on the Planning Portal by using the links below.  

Read about planning permission for extensions

Read about prior approval for larger single storey extensions

Find out about building regulations for an extension

Common Questions

What are Approved Documents and where can I find them?

Approved Documents are official guides that explain how to comply with the building regulations. Published by the government, each document provides practical guidance on meeting the requirements of a specific ‘Part’ of the regulations. They cover a wide range of building work, including plumbing, electrical installations, extensions and ventilation.

The latest versions of the Approved Documents, which support the technical ‘Parts’ of the building regulations, along with Regulation 7, are available on Planning Portal.

Browse the Approved Documents.

Do I need planning permission for external insulation?

Planning permission may be required for external insulation if it impacts the external appearance of the building. If materials are of a similar appearance to those used in the construction of the house, then permission will likely not be required.

Listed buildings will require listed building consent for any significant work.

If you live in a Conservation Area or other protected area you will need to apply for planning permission before making changes to the outside of your house.

 

Further information and building regulations advice is available on Planning Portal. Read our external walls common project.

Do I need permission to brick up an external door?

Bricking up an external door is classified as permitted development, meaning an application for planning permission is not required to complete the works. You will need to ensure that any materials used are of a similar appearance to the existing exterior of the house.

If you live in a listed building, then you will require planning permission and listed building consent for the change. In this instance it is best practice to talk to your local planning authority.

Find your local planning authority.

What are the planning and building rules to add a concrete slope in my front garden for wheelchair access?

Adding a permanent wheelchair ramp for access to a home is likely to require planning permission as it will permanently change the external appearance of the front of the house. If the application is solely for improving disable access to the building then the planning application will be exempt from a planning fee.

If you live in a listed building, you will have to apply for listed building consent for any significant works, whether internal or external.

All permanent wheelchair ramps must comply with Approved Document M of the building regulations which specifies the gradient, width and surfaces which should be used.

Read Approved Document M: Access to and use of buildings.

How high can I build a single-storey extension without planning permission?

A single storey rear extension can fall under permitted development, meaning planning permission may not be required providing it meets certain criteria.  

In terms of height, the extension must:

  • Be no taller than four metres at its highest point
  • Have eaves no higher than the eaves of the original house
  • Not exceed the height of the original dwelling  

Read about planning permission for extensions on Planning Portal

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