Water vapour permeance is the speed at which water goes through a homogeneous material. The National Building Code stipulates that a vapour barrier must have a water vapour permeance of less than 1.05 PERM (60 ng/Pa*s*m2)
- 75 mm of POLARFOAM PF-7300-0 SOYA spray applied on an exterior gypsum board = 44 ng / Pa*s*m2 (0.77 PERM)
- 75 mm of POLARFOAM PF-7300-0 SOYA spray applied on concrete blocks = 22 ng / Pa*s*m2 (0.38 PERM)
This proves that PolarFoam Soya is an effective vapour barrier that performs above code requirements.