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9.26.6.2.(2)
ApplicationIntent
OH1OS2
ObjectiveOH1 Indoor Conditions
Attribution
[F61-OH1.1,OH1.2,OH1.3]
Application
Application 1: 
Fastening of underlay used beneath shingles, on roofs of buildings to which Part 9 applies [see Sentence 1.3.3.3.(1) of Division A for application of Part 9].
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Intent
Intent 1: 
To limit the probability of the retention of water that has penetrated roofing or that has condensed on the underside of underlay, which could lead to long-term wetting of sheathing, which could lead to deterioration, which could lead to further:
  • condensation,
  • precipitation or meltwater ingress, or
  • compromised thermal performance of components intended to provide resistance to heat transfer.
This is to limit the probability of:
  • an inadequate control of relative humidity, temperatures of interior spaces or water accumulation,
  • the generation of pollutants from biological growth or from materials that become unstable on wetting, or
  • further deterioration, which could lead to compromised integrity of roofs or assemblies protected by roofs.
This is to limit the probability of:
  • negative effects on the air quality of indoor spaces,
  • the inadequate thermal comfort of persons, and
  • contact with moisture.
This is to limit the probability of harm to persons.
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