by tony.g »
Fri Jan 13, 2012 9:58 pm
if the garage has been converted to be used as a habitable room, it would need specific planning permission. Normally, separate outbuildings do not need planning permission if they are "incidental to the enjoyment of the dwelling". This includes such uses as a garage, keeping of pets/animals, or as a store for garden tools or large toys for kids etc. The use as what amounts to an additional living room is excluded from the scope of permitted development, and your council planning department would advise on this.
Separately, such a change of use to a habitable room would also need Building Regulations approval, if the room could be used as sleeping accommodation. This is only academic because the use you describe would still need planning permission, even if it was adapted to comply with Building Regulations.