You can determine a shed roof pitch by finding the rise amount in each foot run. Looking on the plans, you will see the roof pitch represented by triangle shaped drawing. This will be written in inches. As the number increases, the inclined angle or pitch gets steeper. The tools needed to determine roof pitch are listed below.
Step 1 – Determine the Rise and Run
The rise is how much incline given in the distance (run = distance). Use a 12-inch level as the run as 12 inches is the standard.
Step 2 – Calculate Rise and Run
Obtain the tangent by dividing the "rise" by the "run." If you know how to use a trig table, you can locate the tangent on that table. Example: “12/12” means the rise is 12 inches and the run is 12 inches. Dividing 12 by 12 gives you a tangent of 1.
Step 3 – Use the Angle Finder
With this method, simply sit the angle finder on a smooth surface. Line it up with the edge of the rake board on the underside of the roof. Since it comes with a built-in protractor scale and floating indicator arrow, you do not have to calculate anything.