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. Whereas we can advise, only the planning department can say for certain that a proposal is PD. When in doubt, we recommend applying for a certificate of lawful proposed development (CoLU) to confirm.
The rules are:
- 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. The roof enlargement cannot overhang the outer face of the wall of the original house.