A loft conversion for your house is considered to be permitted development, not requiring an application for planning permission, provided certain limits and conditions are met.
- Loft conversions are NOT permitted development for houses on designated land*.
- To be permitted development any additional roof space created must not exceed these volume allowances:* 40 cubic metres for terraced houses.* 50 cubic metres for detached and semi-detached houses.Bear in mind that 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.
- An extension beyond the plane of the existing roof slope of the principal elevation that fronts a highway is NOT permitted development.
- Materials to 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 side-facing windows 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, to be set back, as far as is practicable, at least 20cm from the original eaves. The 20cm distance is measured along the roof plane.
- 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.
IMPORTANT NOTE: The permitted development allowances described here apply to houses, not flats, maisonettes or other buildings. You should check with your Local Planning Authority whether permitted development rights apply – they may have been removed by what are known as Article 4 directions. Other consents may be required if your house is listed or in a designated area. When planning work you should read all the advice on the Planning Portal under ‘Your responsibilities – Things to consider be- fore you start’. ‘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 ex- tension to the house, a previous owner may have done so.
‘Designated land’ – Designated land includes national parks and the Broads, Areas of Out- standing Natural Beauty, conservation areas and World Heritage Sites. Source: http://www.planningportal.gov.uk/uploads/miniguides/lofts/Lofts.pdf