Roof Slope Factor Definition

Roof slope factors valley hip factors.

Roof slope factor definition.

How to determine roof pitch or roof slope. Charts are helpful because the factors for hips and valleys are listed which is useful for cutting rafters on the hip or valley. To obtain an accurate roof pitch measurement properly measure the rise and run. Using a tape measure make a pencil mark 12 inches from the end of a carpenter s level.

See low slope roofing. The slope of a roof often referred to as the pitch is determined by rise over run the roof s vertical rise in inches for every twelve inches of horizontal length the run. So a roof with four inches of rise every 12 inches horizontally run would have a slope of 4 12 sometimes displayed as 4 12. Hip and valley rafters slope factor roofs with hips and valleys have special factors.

The headache of using pythagoras and trigonometry can be spared by making use of these charts. So the pitch of a roof is determined by how many inches the slope rises for every 12 inches it runs horizontally. For instance if the measurement was 3 your roof slope factor would be 3 12 and you. Low slope roofing which requires special materials and techniques to avoid leaks and ranges from 1 12 2 12 to 4 12 1 in 3.

In construction the slope factor can be used to easily calculate the area of a roof. A hip or a valley is where two roof slopes intersect forming a peak or a depression. Roof area in square metres length in metres width in metres slope factor. The roof slope factor is written as x 12 where x is the vertical distance you measured from roof to level.

The slope factor works with metric and imperial measurements. Low slope roofs are from 0 to 3 12 in pitch. A 10 slope roof should not be confused with a 10 pitch roof as a 10 slope roof means that the roof rises by ten inches for every foot of run. Then you ll be able to measure slope from an unfinished attic space under the roof.

If a roof increases in height by four inches for every foot of horizontal run it is considered to have a 4 in 12 pitch or just a 4 pitch talk in terms of pitches and you will always be understood in the roofing universe. Some sources consider low slope to include 3 12 pitch roofs. The basic ranges of pitch are not uniformly defined but range from flat which are not perfectly flat but sloped to drain water up to 1 2 12 to 2 12 1 in 24 to 1 in 6. The roof slope factor chart also consists of conversion factors to determine the slope of the roof.

If asphalt shingles are to be installed on a low slope roof special steps are required to avoid short roof life and roof leaks. Conventional from 4 12 1 in 3 to 9 12 3 in 4.