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Do I need planning permission for a single storey extension?

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.

The limits and conditions for building an extension under permitted development rules are covered in our guidance on the Planning Portal, and there are other points to take into consideration.

Visit Planning Portal to find out more.

Common Questions

Is my house in a conservation area?

The UK Government provide access to public land records, allowing you to check certain restrictions on land. You can use the online tool to check whether your land is in a conservation area.

VisitGOV.UK and use the planning data map.

(This map covers planning data for England).

If you are unsure you should contact your local planning authority.

Can I build a two-storey extension without planning permission?

No, a two-storey extension will always require planning permission. Permitted development rights only allow for certain types of single-storey extensions without the need for a planning application, provided they meet specific criteria. All extensions of more than one storey fall outside of these rights and must be assessed through the formal planning process requiring householder planning permission.

Read more about extensions on Planning Portal

Do I need planning permission to add air conditioning to my home?

Adding air conditioning to your home is considered permitted development provided all the limits and conditions set out in legislation are met. The limits set out the size, placement and quantity of air conditioning units allowed.

If your home is in a protected area such as a Conservation Area then permission will be required. If you live in a listed building then consent will be required.

The installation of air conditioning must comply with building regulations. It is advisable to contact an installer who can provide the necessary advice, preferably one who belongs to either the Microgeneration Certification Scheme or the relevant Competent Person Scheme.

For more information on air conditioning, read our heat pumps common project.

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

What is an improvement notice?

An improvement notice is a notice served by a local authority requiring a property owner to carry out specified works to bring a building into compliance with the legal standards. These are most commonly served to landlords to make a building safe.

The notice will specify what works should be completed and when it should begin and be completed by.

Failure to comply with an improvement notice is a criminal offence.

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