To limit the probability of the inadequate splicing of ceiling joists, which could lead to ceiling joist splices being unable to resist the tension forces imposed by expected gravity and lateral loads on rafters, which could lead to the lower end of rafters moving outward, which could lead to:

• the failure of roof rafters or joists, or supporting walls, or
• the excessive deflection of roof rafters or joists, which could lead to damage to roofing.

This is to limit the probability of compromised structural integrity, which could lead to:

• the structural collapse of wood-frame construction,
• where supporting walls serve as an environmental separator or where roof and ceiling framing members support elements 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 of roofs or environmental separators, or
• where roof and ceiling framing members support assemblies exposed to the exterior, excessive water ingress, which could lead to deterioration.

This is to limit the probability of harm to persons.

To limit the probability of the inadequate splicing of ceiling joists, which could lead to ceiling joist splices being unable to resist the tension forces imposed by expected gravity and lateral loads on rafters, which could lead to the lower end of rafters moving outward, which could lead to:

• the failure of roof rafters or joists, or supporting walls, or
• the excessive deflection of roof rafters or joists, which could lead to 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 supporting walls serve as an environmental separator or ceiling joists support elements 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 of roofs or environmental separators.

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.

To limit the probability of the inadequate splicing of ceiling joists, which could lead to ceiling joist splices being unable to resist the tension forces imposed by expected gravity and lateral loads on rafters, which could lead to the lower end of rafters moving outward, which could lead to:

• the failure of roof rafters or joists, or supporting walls, or
• the excessive deflection of roof rafters or joists, which could lead to 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.

To limit the probability of the inadequate splicing of ceiling joists, which could lead to ceiling joist splices being unable to resist the tension forces imposed by expected gravity and lateral loads on rafters, which could lead to the lower end of rafters moving outward, which could lead to:

• the failure of roof rafters or joists, or supporting walls, or
• the excessive deflection of roof rafters or joists, which could lead to 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.

To limit the probability of the inadequate splicing of ceiling joists, which could lead to ceiling joist splices being unable to resist the tension forces imposed by expected gravity and lateral loads on rafters, which could lead to the lower end of rafters moving outward, which could lead to:

• the failure of roof rafters or joists, or supporting walls, or
• the excessive deflection of roof rafters or joists, which could lead to damage to roofing.

This is to limit the probability of the excessive deflection of supporting walls, which could lead to compromised operation of doors or windows required for egress in an emergency, which could lead to harm to persons.