Hi Marvin,
The width of the room is about 5m.
The initial research I did seemed to imply that with a multifoil insulation over the roof joists, I might be able to reduce the thickness of the internal insulation between the roof joists. I need to double check if it could meet the new PT L requirement of no more than 0.15W/m2.
Given that the beams are going to dictate the floor level, I'm looking to see what the smallest size is for the 5m span.
Regards,
Sylvane