INTENT:
To limit the probability that the performance of membrane-type
vapour barriers, other than polyethylene, will fall significantly below expectations
with respect to:
- pliability,
- tensile strength,
- elongation under load, and
- water vapour permeance.
This is to limit the probability of uncontrolled
water vapour diffusion into insulated assemblies, which could lead to condensation,
which could lead to deterioration, which could lead to compromised structural
integrity of assemblies acting as environmental separators, which could lead
to harm to persons.