Permitted Development

Permitted development is development that can be undertaken without the need for a planning application to be submitted to the local planning authority.

From the 1st October 2008 changes to permitted development seek to relax the requirement for planning permission for homeowners to make improvements whilst limiting the size of an extension so that the neighbours are protected.

Under the old Order, householders could only get either a small loft conversion or a rear extension without requiring planning permission. Anyone who had previously extended their property required planning permission for any further alterations.

The new rules will now allow both and will be based on measurements for what is permissible for loft conversions and other extensions separately.

Rear extensions will no longer be calculated by volume for the purpose of permitted development. Loft conversions continue to have an overall volume cap to control overbearing conversions on larger homes. Extensions to the front or principal elevation will still require planning permission.

In conservation areas most extensions and alterations will require permission unless they are single storey and at the rear. For listed buildings the requirement for planning permission is relaxed but listed building consent will still be required. The following are relevant for loft conversions

Class B – Roof extensions
Still calculated by volume above the original roof space to try and avoid overly intrusive roof extensions. Roof extensions will be permitted subject to the following:

  • A volume allowance of 40 cubic metres for terraced houses
  • A volume allowance of 50 cubic metres for detached and semi-detached houses.
  • No extension beyond the plane of the existing roof slope fronting the highway.
  • No extension to be higher than the highest part of the roof.
  • Materials to be similar in appearance to the existing house.
  • No verandas, balconies or raised platforms.
  • Side facing windows to be obscure-glazed; any opening to be 1.7 metres above the floor.
  • Roof extensions not to be permitted development in national parks and the Broads, Areas of Outstanding Natural Beauty, Conservation Areas and World Heritage Sites.
  • Extensions to be set back, as far as practicable, at least 20cm from the eaves except for hip to gable constructions.

Class C – Roof alterations
Minor roof alterations will be permitted development subject to the following:

  • Any alteration to project no more than 150 millimetres from the existing roof plane e.g. the depth of a rooflight window or solar panel.
  • No alteration to be higher than the highest part of the roof.
  • Side facing windows to be obscure-glazed; any opening to be 1.7 metres above the floor.

To put this simply, loft conversions will not require planning permission unless outside of these boundaries.
All Loft Conversions still have to obtain Building Regulation Approval and be monitored in order to achieve a ‘Certificate of Completion’.

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