The Geometry of Roofs




Greetings All,

Did I ever mention that I don't have a whole lot of experience as a framer? I tend to rely on stuff like trig to figure things out, and I like the geometric theory of hip and valley roofs.....the valley rafter is the diagonal of a square....multiply by the square roof of two....right? Not quite. That only works in the horizontal section or what is called the plan. If one multiplies the length of a common rafter by the square root of two to get the valley it don't work so good. I doubt anybody except Martin would care about the explanation which a night of insomnia in 34 degree weather figured out. Anyway I cut seven valley rafters for the four which got installed. Learned a bunch of stuff however.

Next week we will deal with the jack rafters which complete the cross gable, and the overhangs which were designed by Bob Harper as sistered 2x6s. The valley rafters will get cut back to line up with the overhang, but the detail of the square ended overhang on a valley tail eluded me on paper. Week after that we will shoot to get on the plywood and Ice and Snow Membrane for winter tightness, and I suspect that will end this season of building. Roof trim and nice red shingles in the spring. The lack of insulation in the building is felt during the night when we sleep without the kerosene heater running.....burrrrrrrrr in the morning. Love to all...BSB

Posted by Bennett at 6:26 AM EDT | post your comment (0) | link to this post
Updated: Monday, 18 October 2004 6:31 AM EDT