I’m doing a 4m single story half double extension (full single story extension and a half width extension upstairs). I want to do a loft conversion at the same time with a dormer. Will the dormer fall within permitted development or will I need separate planning permission for it? I’ll be staying within permitted development rules I.e. adding less than 50m3 on the semi detached house, but does the double story extension bit count towards the 50m3, so adding a dormer may go over this limit?
