On designated land*, cladding of any part of the exterior of a dwelling (and including extensions/conservatories) with stone, artificial stone, pebble dash, render, timber, plastic or tiles is not permitted development.

On designated land and Sites of Special Scientific Interest the regime for larger single-storey rear extensions (see point 6) does NOT apply.

On designated land extensions on any side wall of the original house are NOT permitted development.

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Definitions of terms used

• Original house - The term ‘original house’ means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date). Although you may not have built an extension to the house, a previous owner may have done so.
• Designated land - Designated land (Article 2(3)) includes national parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites.‍
• Principle elevation - The most visible or prominent side of a structure, typically facing a street or public area. While often considered the 'front' of the building, it may not always contain the main entrance.

Extensions (including previous extensions) and other buildings must not exceed 50% of the total area of land around the original house*.

Sheds and other outbuildings must be included when calculating the 50% limit.

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Definitions of terms used

• Original house - The term ‘original house’ means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date). Although you may not have built an extension to the house, a previous owner may have done so.
• Designated land - Designated land (Article 2(3)) includes national parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites.‍
• Principle elevation - The most visible or prominent side of a structure, typically facing a street or public area. While often considered the 'front' of the building, it may not always contain the main entrance.

Extensions forward of the principal elevation* or side elevation of the original house* and fronting a highway are NOT permitted development.

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Definitions of terms used

• Original house - The term ‘original house’ means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date). Although you may not have built an extension to the house, a previous owner may have done so.
• Designated land - Designated land (Article 2(3)) includes national parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites.‍
• Principle elevation - The most visible or prominent side of a structure, typically facing a street or public area. While often considered the 'front' of the building, it may not always contain the main entrance.

Materials used in exterior work to be similar in appearance to those of the exterior of the existing house. This condition does not apply when the extension is a conservatory.

Side extensions must be single storey and not have a width greater than half the width of the original house*, with a maximum height of four metres.

On designated land* extensions on any side wall of the original house are NOT permitted development.

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Definitions of terms used

• Original house - The term ‘original house’ means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date). Although you may not have built an extension to the house, a previous owner may have done so.
• Designated land - Designated land (Article 2(3)) includes national parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites.‍
• Principle elevation - The most visible or prominent side of a structure, typically facing a street or public area. While often considered the 'front' of the building, it may not always contain the main entrance.

Single-storey rear extensions must not extend beyond the rear wall of the original house* by more than four metres if a detached house; or more than three metres for any other house.

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Where not in designated land* or a Site of Special Scientific Interest, this limit can be increased to eight metres if a detached house; or six metres for any other house but will require an application for prior approval.

Single-storey rear extensions must not exceed a height of four metres.

The ‘prior approval’ process applies only to larger single-storey rear extensions. Find out more about prior approval.

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Definitions of terms used

• Original house - The term ‘original house’ means the house as it was first built or as it stood on 1 July 1948 (if it was built before that date). Although you may not have built an extension to the house, a previous owner may have done so.
• Designated land - Designated land (Article 2(3)) includes national parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites.‍
• Principle elevation - The most visible or prominent side of a structure, typically facing a street or public area. While often considered the 'front' of the building, it may not always contain the main entrance.

Maximum eaves and ridge height of the extension should be no higher than existing house.

If the extension is within two metres of a boundary maximum eaves height should be no higher than three metres to be permitted development.

Most extensions of properties require approval under the building regulations. Read more on Planning Portal.