Discussion Starter · #1 ·
The house has a totally flat roof covering a front porch (9 by 24). I wish to change the pitch from zero to a 4/12 to match the pitch on the existing gable roof. My problem is I don't know, without trial and error, how to cut the front and back ends of the rafters to obtain the correct slope or pitch. I know I can make a jig which is 4 in high and 12 in long or any multiple of those number to give me the pitch but as I said how do I figure the angle on the front and back end of the rafters so that will lay correctly on the existing roof. Hope I have explained this problem to everyone's satisfaction.