Roof Pitch Multiplier Table

Determine how many square feet of roof area a building has by measuring from the ground.

Roof pitch multiplier table.

A roof pitch multiplier also called a roof pitch factor is a number that is multiplied by the area covered by a sloped roof to produce the area of the actual surface of the roof. If you know the pitch of a roof you can use the numbers in the following pitch table to do the following. Roof pitch multiplier table. The hip and valley factor is a number that is multiplied by the actual run horizontal distance of a common rafter to determine the length of a hip or valley rafter.

This table provides the hip and valley factor for common roof pitches as well as the underlying equation for the factor. The roof pitch multiplier table is very helpful in giving correct and reliable roof measurements and uses pythagorean theory. Where a is the rise of the roof b is the run of the roof and c is the rafter hypotenuse of the triangle with side lengths a and b. We excluded roof multipliers for pitch below 3 and above 12 for the following reasons.

For roof slopes expressed as x in 12 rise in run the roof pitch multiplier is determined by finding the square root of rise run 1. Now solving for c in the equation above gives. The formula for the roof pitch multiplier comes from the famous pythagorean theorem. This roof pitch table displays a multiplier for adding for different roof pitches.