Going to give building control a call wednesday anyway but thought i would see if anyone has done this and knows if I would need building regs or not. I have a double garage and at this time of year its absolutely freezing to be out there. so my idea is to plasterboard the ceiling (currently just bare joists) and on top of that add in roughly 270 to 300mm of insulation, I need to leave a gap in the plaster board for a loft hatch which will also be insulated. Given I'm not replcing a existing ceiling not sure if it falls under permitted development or any other loophole of the building regs etc, anyone got any ideas on this thanks