Sentence 6.3.1.2.(1)

Intent 1:

In attic or roof spaces, to limit the probability that inadequate ventilation will lead to:

• the formation of ice dams, which could lead to the ingress into attic or roof assemblies of water backed up by ice dams, or
• the inadequate control of relative humidity, which could lead to condensation and moisture accumulation.

This is to limit the probability of harm to persons.

Intent 2:

In crawl spaces, to limit the probability that inadequate ventilation will lead to condensation, moisture accumulation, or moisture ingress from the ground.

This is to limit the probability of the growth of mould and mildew, which could lead to:

• negative effects on the air quality of indoor spaces, and
• contact with moisture.

This is to limit the probability of harm to persons.