Gable-End Framing and Projections
After roof framing members have been installed, the gable-end studs are nailed in place. Studs in unfinished attics can be placed with the wide face parallel to the wall. Cut the ends of the studs to fit the angle of the rafter and toenail them to the wall plate and to the underside of the rafter with at least four 63 mm (21⁄2 in.) nails at each end (Figure 89). The framing of the roof projections at the gable ends is shown in Figures 89 and 90.
Roofs that project less than 300 mm (12 in.) over the gable-end wall usually terminate with a framing member called a rake rafter (see Figure 90). A 19 mm (3⁄4 in. nominal) nailing strip is fastened to the rafter located above the gable end wall. Blocking spaced at 600 mm (24 in.) on centre is used to support the soffit covering. This blocking is toenailed to the nailing strip and end-nailed to the rake rafter. The soffit covering is then installed and nailed to these supports and a fascia board is added.
Gable-end projections extending more than 300 mm (12 in.) beyond the wall should be supported by framing members called “lookouts” (see Figure 89). Gable-end studs are placed with the narrow face parallel to the sheathing, and a top wall plate is added. The lookout members, usually the same size as the rafters, are spaced at 600 mm (24 in.) on centre.
The ends are supported by end-nailing to the first rafter and inboard of the gable end to the top plate of the gable. Blocking is then fitted between the lookouts in line with the wall line to support the roof sheathing and inner edge of the soffit covering. The soffit covering is nailed to these supports, and a fascia is added. The length of lookout members should be at least twice the width of the roof overhang. A double rafter is used to support the inner ends of the lookout members when they project into the roof more than one-and-one-half rafter spaces.
Source : Canada Mortgage and Housing Corporation (CMHC)