On designated land* extensions of more than one storey 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.

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.

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.

Extensions of more than one storey must not extend beyond the rear wall of original house* by more than three metres or be within seven metres of any boundary opposite the rear wall of the house.

The roof pitch of extensions higher than one storey should match that of the existing house, as far as is practicable.

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.

Materials used in exterior work should be similar in appearance to those of the exterior of the existing house.

Any upper-floor windows in a wall or roof slope of a side elevation must be obscure-glazed and non-opening unless the parts which can be opened are more than 1.7 metres above the floor of the room in which it is installed.

Balconies or verandas are not permitted development.

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