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I have two roofs to worry about on an L-shaped colonial. The L has a hip with 7/12 pitch on either side and the front being 12/12. The other roof is the main being 12/12 with the 7/12 L intersecting square to it.
My first problem, is the cheek cuts on the hip and jacks. Can the compound angle be determined from the scales on the 2-foot square? Or are these scales only good for equal pitch hips? Now that I think about it, I don't even know how to figure the seat cut on this bastard hip. What marks would you hold on the framing square? And how much to drop the seat? (All lumber is 2x and CDX sheathing, so I'm not worrying about backing the hip.) I'd like to learn how to do this without lookup tables, because I know very well, the book will disappear when I need it most.
Second problem is the valley where the 7/12 L intersects the 12/12 main. Am I right in thinking the valley cheek cuts could be figured the same way as the bastard hip jacks? But the bigger problem is a complication I never had to frame for - the both intersecting ceilings under this valley will be cathedral, so the valley rafters can't extend lower than the valley jacks of either the 7/12 or the 12/12. Is there a way to figure the width of the valley w/o putting it up and scribing along a few points of the valley jacks? And what about a bevel on the bottom of the valley, how would you figure these bevel angles? (It seems to me this is going to be a lot of trial and error, but structurally AND cosmetically it has to look right by the time I'm done. I don't want to go into a job having to rely on rockers and tapers to cover my experiments)
I know I'm not the first to have to do this, so all advice and experience is welcome.