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9.23.4.2.(1)
OS2OP2OH1OH4OS1OS3
ObjectiveOS3 Safety in Use
Attribution
[F22-OS3.1] Applies to floors and elements that support floors.
[F22-OS3.7] Applies to walls, and elements that support walls, that contain doors or windows required for emergency egress.
Application
Application 1: 
Maximum spans, in wood-frame constructions to which Section 9.23. applies [see Sentence 9.23.1.1.(1) for application of Section 9.23.], for:
  • lumber joists used to support floors
    • in residential areas,
    • where the live load does not exceed 1.9 kPa, or
    • supporting a topping of concrete that is of normal weight and 38 to 51 mm thick, that is placed directly on the subflooring, and that has not less than 20 MPa compressive strength after 28 days [see Article 9.23.4.4.],
  • lumber joists and rafters used to support roofs:
    • where specified snow loads do not exceed 3.0 kPa, and
    • that are not required to support an additional uniform dead load from materials heavier than asphalt or wood shingles, wood shakes, built-up, selvage, sheet metal, glass reinforced, hot rubberized asphalt or polyvinyl chloride sheet roofing [see Sentence 9.23.4.5.(1)], and
  • lumber joists used to support ceilings.
Exceptions: 
except:
  • for constructions designed according to Part 4 for the same loading conditions and not exceeding the design criteria for uniform loading and vibration,
  • as stated in Sentence 9.23.4.4.(1), which applies to floors supporting concrete toppings other than described above, and
  • as stated in Sentence 9.23.4.5.(1), which applies to roofs required to support an additional dead load from materials heavier than asphalt or wood shingles, wood shakes, built-up, selvage, sheet metal, glass reinforced, hot rubberized asphalt or polyvinyl chloride sheet roofing.
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Intent
Intent 1: 
To limit the probability of excessively long spans, which could lead to an inability to resist expected lateral, gravity or wind-uplift loads.
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.
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