In general the hip valley rafter needs to be one to two sizes larger than the jack rafters, if you can add a few support braces. The jack rafters were pulling away from the hip valley rafter due to the excessive deflection. I have added pictures of Friday’s inspection where the 2圆 hip valley rafter had about a 4" deflection mid-span. Total deflection was 73% of the maximum allowable by code for the single LVL and 65% for the double LVL beam. The two 2x12s failed 220% in bending and 6% in deflection.To make the hip valley rafter a clear span beam it needed to be one LVL beam 1-3/4" x 11-1/4", 2.0E, 2950Fb or two LVL beams 3-1/2" x 9-1/4". The hip valley rafter failed in all combinations including two 2x12s, which was modeled without intermediate supports. By adding a mid-span support the 2圆 common rafter passes. Based on the loading the common rafter without intermediate bracing fails in bending and deflection. The loading is based on a shingle roof, 1/2" plywood on #2 D.Fir-L 2圆 rafters. I did the calculations and the common rafter carries 7.42#/linear foot deal load (DL) and 20.48#/linear foot snow load (SL). Just by visual observation you can see the hip valley rafter carries significantly more load than the common rafter. The yellow shaded areas show the area loading that is transferred to the common rafter and the hip valley rafter. The hip valley rafter is 22’-8" long with the attached jack rafters at 16" on center. In this graphic the common rafters are 17 feet long spaced at 16" on center. Most of the time the hip valley rafter is the same size as the common rafter. I have attached a graphic showing the loading on a common rafter and a hip valley rafter.
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