Roof Pitch Multiplier Table

The formula for the roof pitch multiplier comes from the famous pythagorean theorem.

Roof pitch multiplier table.

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. If you know the pitch of a roof you can use the numbers in the following pitch table to do the following. With pitch under 3 you can easily walk on the roof to get the exact measurements as that is usually a flat roof. Determine how many square feet of roof area a building has by measuring from the ground.

Accurate roof calculations are achieved using this table and all you need to do is measure the roof width and length and then you are ready to do a roof pitch measurement. 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. This table provides the hip and valley factor for common roof pitches as well as the underlying equation for the factor. 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.

Roof pitch multiplier table. Now solving for c in the equation above gives. We excluded roof multipliers for pitch below 3 and above 12 for the following reasons. The roof pitch multiplier table is very helpful in giving correct and reliable roof measurements and uses pythagorean theory.