What formula expresses the slope of a roof?

The slope of a roof is commonly expressed using the rise over run formula. In this context, "rise" refers to the vertical change in height of the roof, while "run" represents the horizontal distance over which that rise occurs. By calculating the ratio of rise to run, this formula provides a clear measure of the steepness of the roof, which is crucial for ensuring proper water drainage and structural integrity.

Using rise/run allows builders and architects to determine the pitch of the roof, which in turn informs decisions regarding materials, construction techniques, and the overall design aesthetic. This ratio is typically expressed in terms of a slope ratio (e.g., 4:12), providing a standardized way to communicate the steepness of different roof designs.

Other formulas listed, while they involve height and width, do not accurately represent the conventional way to represent roof slope and may lead to confusion in practical applications. Thus, rise/run remains the most widely accepted and understood formula for expressing roof slope.