This is usually permitted development and planning permission isn’t generally required, unless the work involves enlarging the building or altering the roof structure – for example changing it from a flat roof to a pitched.
A new housing development or in a conservation area may have permitted development rights removed from some properties with regard outbuilding and garage conversions and therefore you should contact your local planning authority before proceeding.
Whenever work is proposed to a listed building, listed building consent may be required.
For more information on Listed building consent, please read news section:
You will need to obtain Building Regulations approval for the work, however to ensure the conversion meets the current building regulations in particular, fire safety/means of escape in the event of a fire, thermal efficiency, and ventilation