Back9.4.2.2.(1)

ATTRIBUTION:

Functional Statement:

F20

To support and withstand expected loads and forces.

F22

To limit movement under expected loads and forces.

Objective:

OS2.1, OS2.3, OS2.3

 

APPLICATION:

Specified snow loads on roofs of light-frame constructions where wall, floor and roof planes are generally comprised of frames of small repetitive structural members, and where:
  • roof and wall planes are clad, sheathed or braced on at least one side,
  • the small repetitive structural members are spaced not more than 600 mm o.c.,
  • the clear span of any structural member does not exceed 12.2 m,
  • the maximum deflection of the structural roof members conforms to Article 9.4.3.1.,
  • the maximum total roof area, regardless of firewalls, is 4 550 m2, and
  • for flat roofs, there are no significant obstructions on the roof, such as parapet walls, spaced closer than the distance calculated by: Do=10Ho-0.8 Ss/g where Do = minimum distance between obstructions, m, Ho = height of the obstruction above the roof, m, Ss = ground snow load, kPa, and γ = unit weight of snow, kN/m3.
This applies to buildings to which Part 9 applies [see Sentence 1.3.3.3.(1) of Division A for application of Part 9].

INTENT:

To limit the probability that inaccurate snow load assumptions will lead to assemblies being unable to resist gravity, snow and rain loads.
This is to limit the probability of compromised structural integrity, which could lead to:
  • structural failure, or
  • for environmental separators or elements supporting environmental separators, the displacement or failure of required environmental separation elements, which could lead to the deterioration of building elements.
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:

OP2.1, OP2.3, OP2.3

 

APPLICATION:

Specified snow loads on roofs of light-frame constructions where wall, floor and roof planes are generally comprised of frames of small repetitive structural members, and where:
  • roof and wall planes are clad, sheathed or braced on at least one side,
  • the small repetitive structural members are spaced not more than 600 mm o.c.,
  • the clear span of any structural member does not exceed 12.2 m,
  • the maximum deflection of the structural roof members conforms to Article 9.4.3.1.,
  • the maximum total roof area, regardless of firewalls, is 4 550 m2, and
  • for flat roofs, there are no significant obstructions on the roof, such as parapet walls, spaced closer than the distance calculated by: Do=10Ho-0.8 Ss/g where Do = minimum distance between obstructions, m, Ho = height of the obstruction above the roof, m, Ss = ground snow load, kPa, and γ = unit weight of snow, kN/m3.
This applies to buildings to which Part 9 applies [see Sentence 1.3.3.3.(1) of Division A for application of Part 9].

INTENT:

To limit the probability that inaccurate snow load assumptions will lead to assemblies being unable to resist gravity, snow and rain loads.
This is to limit the probability of compromised structural integrity, which could lead to:
  • structural failure,
  • for environmental separators or elements supporting environmental separators, the displacement or failure of required environmental separation elements, which could lead to the deterioration of building elements, which could lead to further compromised integrity, or
  • an inability to resist expected loads, which could lead to
    • the excessive deformation or deflection of walls, or
    • the excessive deflection or vibration of floors.
This is to limit the probability of damage to the building.

ATTRIBUTION:

Functional Statement:

F22

To limit movement under expected loads and forces.

Objective:

OH1.1, OH1.2, OH1.3

 

APPLICATION:

Specified snow loads on roofs of light-frame constructions where wall, floor and roof planes are generally comprised of frames of small repetitive structural members, and where:
  • roof and wall planes are clad, sheathed or braced on at least one side,
  • the small repetitive structural members are spaced not more than 600 mm o.c.,
  • the clear span of any structural member does not exceed 12.2 m,
  • the maximum deflection of the structural roof members conforms to Article 9.4.3.1.,
  • the maximum total roof area, regardless of firewalls, is 4 550 m2, and
  • for flat roofs, there are no significant obstructions on the roof, such as parapet walls, spaced closer than the distance calculated by: Do=10Ho-0.8 Ss/g where Do = minimum distance between obstructions, m, Ho = height of the obstruction above the roof, m, Ss = ground snow load, kPa, and γ = unit weight of snow, kN/m3.
This applies to buildings to which Part 9 applies [see Sentence 1.3.3.3.(1) of Division A for application of Part 9].

INTENT:

To limit the probability that inaccurate snow load assumptions will lead to assemblies being unable to resist gravity, snow and rain loads.
This is to limit the probability of excessive movement, deformation or damage to roofing, which could lead to:
  • precipitation ingress, or
  • air leakage, which could lead to compromised thermal performance of components intended to provide resistance to heat transfer.
This is to limit the probability of:
  • an 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 compromised integrity of environmental separators or of elements protected by such 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.