We are proposing to use the Colorcoat Urban steel roofing system from Tata Steel. The roof will be a shallow pitch (about 9.5 degrees).
The top 3 layers (top down) are steel sheet breathable membrane
18mm OSBWe are proposing a warm roof solution, with the next layers being:
50mm PIR 150*50 rafters with 100mm PIR between Foil backed plasterboardSo: (1) Should this need any more vapour barriers anywhere (2) Should the PIR be at the top of the rafters with a void below (seems sensible).
Cheers
Dave R