The planning regulations were changed in October 2008 and this included many changes to the rules governing loft conversions.

In certain circumstances, planning permission is not required and the building is deemed to fall within ‘permitted development’ (i.e. it is treated as minor works that will have limited impact on the environment).

We have listed on page 2 the circumstances where loft conversions do not require planning permission but we strongly recommend that you obtain confirmation of this from your local planning office as this will be useful when selling the property in the future (see our factsheet on Permitted Development).

Also be aware that most loft conversions will require building regulations approval which is a completely separate process from planning permission and deals with the technical performance of the building (see our factsheet on Building Regulations for Loft Conversions).

Planning Permission is not required for loft conversions under the following circumstances:

1. Where the loft conversion does not include new dormer windows, it will usually not require planning permission providing that any roof lights do not project more than 150mm from the existing roof plane.
2. The volume of any new dormers or other increase to the roof should be less than 40 cubic metres for terraced houses. Any previous roof space additions must be included within the volume allowance including additional space created by previous owners.
3. The volume of any new dormers or other increase to the roof should be less than 50 cubic metres for detached and semi-detached houses. Any previous roof space additions must be included within the volume allowance including additional space created by previous owners.
4. No extension is allowed beyond the plane of the existing roof slope of the principal elevation that fronts the highway. If, for example, you are forming a dormer window at the front of your property and it extends towards the road, it will require planning permission.
5. Any extension shall not be higher than the highest part of the existing roof
6. Materials should be similar in appearance to the existing house
7. No verandas, balconies or raised platforms are permitted
8. Any side-facing windows are to be obscure-glazed; any opening to be 1.7m above the floor
9. Roof extensions within designated areas will require planning permission. Designated areas include national parks and the Broads, Areas of Outstanding Natural Beauty, conservation areas and World Heritage Sites.
10. Roof extensions, apart from hip to gable ones, are to be set back, as far as practicable, at least 20cm from the eaves.

Flats and Maisonettes

Please note that different rules apply to flats and maisonettes and generally most loft conversions to flats or maisonettes will require planning permission. In some circumstances, where no dormer window is proposed, planning permission may not be required but we would recommend that you consult your local planning office as local interpretation can vary.

Listed Buildings

Where work is proposed to a listed building, listed building consent may be required.

Whilst you will pleased to receive approval for your proposed works, be aware that most certificates will include conditions such as those shown in the sample below.

View the sample certificate here