• Assemblies separating the indoor air from the outdoor air must be constructed with an air barrier that will provide a continuous barrier to air leakage:
  • from the inside into the assemblies enough to prevent excessive moisture condensation
  • From the exterior or the ground inwards, enough to:
    • Prevent moisture condensation on the room side
    • Ensure comfortable conditions for the occupants
    • Minimize the ingress of soil gas

9.25.3.1.(1) Wall, ceiling and floor assemblies separating conditioned space from unconditioned space or from the ground shall be constructed so as to include an air barrier system that will provide a continuous barrier to air leakage

a) from the interior of the building into wall, floor, attic or roof spaces, sufficient to prevent excessive moisture condensation in such spaces during the winter, and

b) from the exterior or the ground inward sufficient to

i) prevent moisture condensation on the room side during winter,

ii) ensure comfortable conditions for the occupants, and

iii) minimize the ingress of soil gas.