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Work on the roof

NOTE: This guidance applies only until 1 October 2008 when new permitted development rules and conditions come into force.

You will need to apply for planning permission if you live in a Conservation Area, a National Park, an Area of Outstanding Natural Beauty or the Broads and you want to build an extension to the roof of your house or any kind of addition which would materially alter the shape of the roof.

If you live in a listed building, you will need listed building consent for any significant works whether internal or external.

Outside those areas, you need to apply for planning permission if any of the following following is true.

  • The work would make some part of the house higher that the highest part of the existing roof.
  • The dormer or other addition you want to build would extend beyond the plane of any existing roof slope facing a highway.
  • A roof extension would add more than 40 cubic metres to the volume of a terraced house or more than 50 cubic metres to any other kind of house.

Note: additional volume created by an extension - and that includes roof extensions - will count against the total volume limit for your house. So you will also need to apply for planning permission before building a roof extension if:

  • for a terraced house the volume of the "original house" would be increased by more than 10% or 50 cubic metres (whichever is greater)
  • for any other kind of house, the volume of the "original house" would be increased by more than 15% or 70 cubic metres(whichever is greater)
  • the volume of the "original house" would be increased by more than 115 cubic metres

 

Calculating the volume of a building or extension is not easy. It is important to get it right if you are deciding whether planning permission will be needed. To help you we have provided a handy calculator (The answer to the calculation is always given in metric because the relevant legislation uses metric measurements).

Launch the calculator here

(opens in a new window which you may need to resize).

Requires Flash. Download the free plug-in from Adobe.

Common projects: Roofs

Disclaimer: this is an introductory guide and is not a definitive source of legal information. Read the full disclaimer here.

NOTE: This guidance relates to the planning regime for England. Policy in Wales may differ. If in doubt contact your Local Planning Authority.