Select this option if you know the rafter's Run(R) and the roof's Pitch(X), and need to determine the Rise(M) of the rafter.
Rise(M) - This option places the Run(R) and Pitch(X) fields into the Input section, and moves the Rise(M) field to the Results section. The pitch is represented as the number of inches of Rise for every 12 inches of Run. Pitch(X) - This option (the default) places the Rise and Run fields into the Input section. The Roof Pitch Calculator Input Options (explained) To determine the Y height, measure from the bird's mouth up the calculated slope ( X in 12) to the top of the rafter. To determine the finished height of the ridge beam, add the Rise ( M) and the Y height.
