Architect has specified our build to have 100 Cavity with 50mm celotex and a 50mm air gap but ive managed to get 75mm celotex cheaper than the 50mm it is in 1.2mX2.4m sheets so presume it will need to be cut up to install. The wall would be 75mm Insulation and 25mm air gap would that cause any problems?
Apologies if this is a silly question
Apologies if this is a silly question