Measuring the slope of a roof requires taking measurements from the top to bottom of the roof using a 12-inch ruler and level. The ruler and level are used to determine how many inches of drop there is over a set horizontal distance, usually 12 inches, to calculate the roof slope as a ratio like 4/12 or 9/12.

1. Calculating Roof Slope
•Mearsurements are taken top to bottom
•Use 12'' ruler, level