For instance a 38 panel will have an effective coverage width of 36. The roofs pitch is the number of inches the roof rises in 12 inches. You can use the following equations to find the length of the rafter and the slope.
Measuring Slope from the Roof Surface 1.
Use the framing square to get roof slope We can reverse the usual use of a framing square finding the rafter length to figure out the roof dimensions or slope. Use the framing square to get roof slope We can reverse the usual use of a framing square finding the rafter length to figure out the roof dimensions or slope. For a roof slope expressed as X-in-12 rise-in-run the hip and valley factor is determined by finding the square root of riserun² 2 for the slope of the adjacent roof sections. How to calculate roof pitch.