Figure 2-48.—Method of framing gable dormer with sidewalls.method of framing, the shortening allowance for theupper end of a valley rafter is one-half the 45° thicknessof the inside member in the upper doubled header. Thereis also a shortening allowance for the lower end,consisting of one-half the 45° thickness of the insidemember of the doubled common rafter. The figure alsoshows that each valley rafter has a double side cut at theupper and lower ends.Figure 2-48 shows a method of framing a gabledormer with sidewalls. As indicated in the framingdiagram, the total run of a valley rafter is again thehypotenuse of a right triangle with the shorter sides eachequal to the run of a common rafter in the dormer. Youfigure the lengths of the dormer corner posts and sidestuds just as you do the lengths of gable-end studs, andyou lay off the lower end cutoff angle by setting thesquare to the cut of the main roof.Figure 2-49 shows the valley rafter shorteningallowance for this method of framing a dormer withsidewalls.Figure 2-49.-Valley rafter shortening allowance for dormerswith sidewalls.Figure 2-50.-Types of jack rafters.Jack RaftersA jack rafter is a part of a common rafter, shortenedfor framing a hip rafter, a valley rafter, or both. Thismeans that, in an equal-pitch framing situation, the unitof rise of a jack rafter is always the same as the unit ofrise of a common rafter. Figure 2-50 shows various typesof jack rafters.A hip jack rafter extends from the top plate to a hiprafter. A vane y jack rafter extends from a valley rafterto a ridge. (Both are shown in fig. 2-51.) A cripple jackrafter does not contact either a top plate or a ridge. A2-30
Integrated Publishing, Inc. - A (SDVOSB) Service Disabled Veteran Owned Small Business
