Having bought an old converted coachhouse from the turn of the century that had all it's character boarded up when it was turned into living accommodation, I am in the process of trying to bring back out of much of it as I can. The upstairs floor has a sloping roof joining partway down the side walls, with a ceiling that covered up about 1 metre of attic space above, which I've taken down, exposing all the rafters - which I now need to insulate, but I understand I need to leave a 50mm gap to promote airflow. The roof itself does have vents in the tiles in various places, but I'm struggling to understand how 'ventilation' will actually be achieved - as there is no air access at the bottom (i.e. soffit/fascia area). Once the ceiling is on, it's effectively sealed.
My original plan had been to wedge 75mm celotex inbetween the rafters right up to the felt, surely this would be a better solution, as - if there are no voids - no air can condense and cause problems?
My original plan had been to wedge 75mm celotex inbetween the rafters right up to the felt, surely this would be a better solution, as - if there are no voids - no air can condense and cause problems?