Sentence 5.9.3.4.(2)

Intent 1:

To limit the probability that the airtightness of other fenestration assemblies will be inadequate for the control of:

• the ingress of precipitation due to air pressure differences,
• the condensation of moisture from interior spaces on interior surfaces or within assemblies, or
• the ingress of airborne moisture into or through assemblies.

This is to limit the probability of deterioration, which could lead to compromised structural integrity of environmental separators or of elements supported or protected by the separators, which could lead to structural failure, which could lead to harm to persons.