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

Two storey rear extensions are considered to be permitted development, meaning they do not require an application for planning permission provided certain limits and conditions are met. If these limits are exceeded then you will need to apply for planning permission from the local planning authority.

Houses on designated land such as national parks or conservation areas are excluded from the permitted development rights and will require an application for planning permission.

To fall within permitted development rights, the extension should be no higher than the existing house, and where it is within two metres of a boundary, the eaves should be no higher than three metres. 

Any double storey extension to the side or front of the house will require planning permission. You can view the full limits and conditions on our Two-storey extension Mini Guide.

If you live in a listed building you will require listed building consent for any major works to the property.

Common Questions

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

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

The rights only apply if the system provides a heating function (including if it can provide both heating and cooling). If the system only offers a cooling function, then the rights do not apply and an application for planning permission will be required.

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.

Do summerhouses or garden offices need building regulations approval?

If you plan to put up a small, detached building like a garden shed, garden room, garden office, annexe or summerhouse (all classed as outbuildings), building regulations generally won’t apply if the building has a floor area under 15 square metres and does not include any sleeping accommodation.

For buildings with a floor area between 15 and 30 square metres, building regulations approval is usually not needed - as long as the building does not include sleeping accommodation and either:

  • it is at least one metre away from any boundary, or
  • it is built mainly from non-combustible materials.

Read more about the building regulations that apply to outbuildings.

Don't forget to check the permitted development rights for outbuildings.

Where can I find information about change of use class from C3 to C2?

An application for full planning permission for a change of use is often required when changing from a house (use class C3) to a residential institution (use class C2). This is due to the increased activity which a C2 use would have on the local street area through the addition of visitors, staff and changes to parking.

Read additional information on use classes and changes of use.

What is the process for applying for planning permission?

When you, or an agent acting on your behalf, have submitted a planning application, the local authority will firstly check the application to check if it’s complete. This validation process allows the authority to ensure everything that is required to decide an application has been received and provided correctly. They will contact you if they require any further information from you.

After the application has been validated, the determination process begins and takes up to 8 weeks for smaller applications, or up to 13 weeks for larger applications. The authority should be able to give you an idea about the likely timetable. The local authority will contact you with their decision.

Read more about the decision-making process for planning applications.

What are non-material changes to an application for planning permission?

Following a grant of planning permission, it may be necessary to make amendments to the proposals that were originally approved. A non-material amendment may be applied for to approve a minor change to the planning permission which does not breach any conditions originally placed on the consent.

There is no statutory definition for ‘non-material’ as it can vary on a case-by-case basis. In general, if the change will increase the size, change the appearance of a development or have a large impact on other considerations then it will not be considered non-material.

Read more about this non-material amendment applications.

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