Back9.23.4.5.(1)

ATTRIBUTION:

Functional Statement:

F20

To support and withstand expected loads and forces.

F22

To limit movement under expected loads and forces.

F20

To support and withstand expected loads and forces.

F22

To limit movement under expected loads and forces.

Objective:

OS2.1, OS2.5, OS2.4, OS2.5, OS2.3

 

APPLICATION:

Reduction in maximum spans for wood joists, rafters, lintels and ridge beams, in wood-frame constructions to which Section 9.23. applies [see Sentence 9.23.1.1.(1) for application of Section 9.23.], used to support roofs with roofing materials that are heavier than:
  • asphalt shingles,
  • wood shingles or shakes,
  • built-up roofing,
  • selvage asphalt roofing,
  • sheet metal,
  • glass-reinforced polyester,
  • hot-applied rubberized asphalt, or
  • polyvinyl chloride sheet.

INTENT:

To limit the probability of excessively long spans, which could lead to roofs being unable to support additional loads imposed by heavier roofing materials, which could lead to excessive movement, deformation or damage to roofing.
This is to limit the probability of compromised structural integrity, which could lead to:
  • the structural collapse of wood-frame construction, or
  • where wood-frame construction supports or is part of an environmental separator, the excessive deformation, displacement or failure of required environmental separation elements, which could lead to deterioration, which could lead to further compromised structural integrity.
This is to limit the probability of harm to persons.

ATTRIBUTION:

Functional Statement:

F20

To support and withstand expected loads and forces.

F22

To limit movement under expected loads and forces.

F20

To support and withstand expected loads and forces.

F22

To limit movement under expected loads and forces.

Objective:

OP2.1, OP2.5, OP2.4, OP2.5, OP2.3

 

APPLICATION:

Reduction in maximum spans for wood joists, rafters, lintels and ridge beams, in wood-frame constructions to which Section 9.23. applies [see Sentence 9.23.1.1.(1) for application of Section 9.23.], used to support roofs with roofing materials that are heavier than:
  • asphalt shingles,
  • wood shingles or shakes,
  • built-up roofing,
  • selvage asphalt roofing,
  • sheet metal,
  • glass-reinforced polyester,
  • hot-applied rubberized asphalt, or
  • polyvinyl chloride sheet.

INTENT:

To limit the probability of excessively long spans, which could lead to roofs being unable to support additional loads imposed by heavier roofing materials, which could lead to excessive movement, deformation or damage to roofing.
This is to limit the probability of compromised structural integrity, which could lead to:
  • the structural collapse of wood-frame construction, or
  • where wood-frame construction supports or is part of an environmental separator, the excessive deformation, displacement or failure of required environmental separation elements, which could lead to deterioration, which could lead to further compromised structural integrity.
This is to limit the probability of:
  • the space being unsuitable for its intended use,
  • compromised operation of windows or doors, or
  • damage to the building.

ATTRIBUTION:

Functional Statement:

F20

To support and withstand expected loads and forces.

F22

To limit movement under expected loads and forces.

Objective:

OH1.1, OH1.2, OH1.3

 

APPLICATION:

Reduction in maximum spans for wood joists, rafters, lintels and ridge beams, in wood-frame constructions to which Section 9.23. applies [see Sentence 9.23.1.1.(1) for application of Section 9.23.], used to support roofs with roofing materials that are heavier than:
  • asphalt shingles,
  • wood shingles or shakes,
  • built-up roofing,
  • selvage asphalt roofing,
  • sheet metal,
  • glass-reinforced polyester,
  • hot-applied rubberized asphalt, or
  • polyvinyl chloride sheet.

INTENT:

To limit the probability of excessively long spans, which could lead to roofs being unable to support additional loads imposed by heavier roofing materials, which could lead to excessive movement, deformation or 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.

ATTRIBUTION:

Functional Statement:

F20

To support and withstand expected loads and forces.

F22

To limit movement under expected loads and forces.

Objective:

OS1.2

 

APPLICATION:

Reduction in maximum spans for wood joists, rafters, lintels and ridge beams, in wood-frame constructions to which Section 9.23. applies [see Sentence 9.23.1.1.(1) for application of Section 9.23.], used to support roofs with roofing materials that are heavier than:
  • asphalt shingles,
  • wood shingles or shakes,
  • built-up roofing,
  • selvage asphalt roofing,
  • sheet metal,
  • glass-reinforced polyester,
  • hot-applied rubberized asphalt, or
  • polyvinyl chloride sheet.

INTENT:

To limit the probability of excessively long spans, which could lead to roofs being unable to support additional loads imposed by heavier roofing materials, which could lead to excessive movement, deformation or damage to roofing.
Where assemblies are required to provide fire resistance, this is to limit the probability of compromised fire resistance of the assembly, which could lead to harm to persons.

ATTRIBUTION:

Functional Statement:

F22

To limit movement under expected loads and forces.

F22

To limit movement under expected loads and forces.

Objective:

OS3.1, OS3.7

 

APPLICATION:

Reduction in maximum spans for wood joists, rafters, lintels and ridge beams, in wood-frame constructions to which Section 9.23. applies [see Sentence 9.23.1.1.(1) for application of Section 9.23.], used to support roofs with roofing materials that are heavier than:
  • asphalt shingles,
  • wood shingles or shakes,
  • built-up roofing,
  • selvage asphalt roofing,
  • sheet metal,
  • glass-reinforced polyester,
  • hot-applied rubberized asphalt, or
  • polyvinyl chloride sheet.

INTENT:

To limit the probability of excessively long spans, which could lead to roofs being unable to support additional loads imposed by heavier roofing materials, which could lead to excessive movement, deformation or damage to roofing.
This is to limit the probability of:
  • compromised structural integrity,
  • where elements support or are part of an environmental separator, the failure of required environmental separation elements, which could lead to deterioration, or
  • an inability to resist expected loads, which could lead to:
    • the excessive deflection or vibration of floors, or
    • the excessive movement or deformation of walls.
This is to limit the probability of:
  • compromised operation of doors or windows required for egress in an emergency, and
  • persons losing their balance, tripping or falling.
This is to limit the probability of harm to persons.