Listed building require specific listed building consent, and those living in a conservation area, area of outstanding natural beauty or national part will generally need to apply for planning permission.
As long as the following conditions are met, you generally shouldn’t need planning permission:
- Total roof extensions, past and present, do not exceed 40m³ for terraced houses or 50m³ for semi-detached or fully detached home
- The extension does not go beyond the roof slope facing the highway
- No part of the new extension reaches higher than the existing roof
- There are no raised platforms or balconies
- Materials used are closest to or exact matches to the original house
- Any extensions do not overhang the outer face of the house