Loft conversions are NOT permitted development for houses on designated land*.

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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.

To be permitted development, any additional roof space created must not exceed 40 cubic metres for terraced houses and 50 cubic metres for detached and semi-detached houses.

Any previous roof space additions must be included within this volume allowance. Although you may not have created additional space a previous owner may have done so.

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An extension beyond the plane of the existing roof slope of the principal elevation* that fronts a highway is NOT permitted development.

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Definitions of terms used

• 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 should be similar in appearance to the existing house.

No part of the extension to be higher than the highest part of the existing roof.

Verandas, balconies or raised platforms are NOT permitted development.

Any 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.

Roof extensions, apart from hip to gable ones, must be set back as far as is practicable, and no less than 20cm from the original eaves. The 20cm distance is measured along the roof plane.

The roof enlargement cannot overhang the outer face of the wall of the original house*.

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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.

Work on a loft or a roof may affect bats. You need to consider protected species when planning work of this type. A survey may be needed, and if bats are using the building, a licence may be required.

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Contact Natural England for more advice

View specific information regarding Bats

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Building regulations approval is required to convert aloft or attic into a liveable space. Read further guidance on Planning Portal.