Sentence 9.25.4.3.(1)

Intent 1:

To limit the probability of:

• inadequate coverage of wall, ceiling and floor assemblies with vapour barrier products, or
• vapour barrier installation at a plane in the building envelope where the temperature is sufficiently low to cause the condensation of water vapour from interior spaces on interior surfaces or within assemblies.

This is to limit the probability of uncontrolled water vapour diffusion into 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.