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9.23.5.5.(1)
ApplicationIntent
OS2OP2OH1OS1
ObjectiveOH1 Indoor Conditions
Attribution
[F20,F22-OH1.1,OH1.2,OH1.3] Applies to elements that support or are part of an environmental separator.
Application
Application 1: 
Notching, drilling or otherwise weakening wood roof trusses, in wood-frame constructions to which Section 9.23. applies [see Sentence 9.23.1.1.(1) for application of Section 9.23.].
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Intent
Intent 1: 
To limit the probability of an overly reduced cross-section, which could lead to an inability to resist expected gravity and lateral loads, which could lead to excessive movement or deformation, or bending or buckling failure, which could lead to excessive deflection and damage to roofing.
Where wood-frame construction supports or is part of an environmental separator, this is to limit the probability of the displacement or failure of required environmental separation elements, which could lead to:
  • condensation,
  • precipitation ingress,
  • excessive heat transfer,
  • pollutant ingress, or
  • compromised thermal performance of components intended to resist heat transfer.
This is to limit the probability of:
  • inadequate control of temperatures of interior spaces, drafts, relative humidity or water accumulation,
  • the generation of pollutants from biological growth or from materials that become unstable on wetting, or
  • deterioration, which could lead to further compromised integrity of environmental separators.
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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