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9.26.3.1.(2)
ApplicationIntent
OS2OH1
ObjectiveOH1 Indoor Conditions
Attribution
[F20,F61,F80-OH1.1,OH1.2,OH1.3]
Application
Application 1: 
Slopes for asphalt and gravel roofs and coal tar and gravel roofs that do not conform to the minimum slopes required by Table 9.26.3.1. and are provided with effective roof drains located at the lowest points of roofs, on 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 water ponding on roof surfaces for extended periods, which could lead to:
  • water penetrating roofing membranes,
  • accelerated weathering of roofing materials, or
  • the roof's structural design loads being exceeded, which could lead to excessive deflection and further ponding.
This is to limit the probability of damage or premature failure of roofing components, which could lead to:
  • 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
  • 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.
Intent 2: 
To expand the application of Sentence 9.26.3.1.(1) to allow lower slopes where drainage is provided.
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