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For pitched roofs framed with dimension lumber, nail the ceiling joists in place after the interior and exterior wall framing is complete but before the rafters are erected, because otherwise the thrust of the rafters will tend to push out the exterior walls. Ceiling joists are generally used to tie the lower ends of the rafters in pitched roofs that slope 1:3 or more. To prevent the rafter ends from moving outward, nail the ceiling joist to the side of each pair of rafters (Figure 83). For hip roofs
where jack rafters run perpendicular to the ceiling joists, a stub joist can tie the jack rafter back to the ceiling joist (Figure 85). Lap and nail the joists together or splice them at the centre load-bearing wall to provide a continuous tie across opposing rafters. The number of nails required in the connections depends upon the roof slope, rafter spacing, snow load and the width of the house. (See Table 24 on p. 288 for nailing requirements.)
83 Roof framing and attachment
A
Gable roof
ridge board rafter collar brace collar tie gable end stud ceiling joist top wall plate
B
Hip roof
hip rafter at least 50 mm (2 in.) deeper than jack rafters jack rafter ceiling joist top plate