Minimum Roof Pitch Angle

So if your roof rises 4 inches for every 12 inches of horizontal length then the pitch of your roof is expressed as 4 12.

Minimum roof pitch angle.

The picture below shows the pitch of a 7 12 roof slope meaning that for 12 of horizontal measurement roof run the vertical measurement roof rise is 7. High pitched roofs often need extra fasteners and their pitch can be as high as 21 12. So the pitch of a roof is determined by how many inches the slope rises for every 12 inches it runs horizontally. However you can only use this pitch with built up roofing or specialized synthetic roofing.

What is the minimum slope for an asphalt shingle roof. Roof pitch and corresponding angles. This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement. The 2 12 number is rise over run or two units of vertical for every 12 units horizontal.

Asphalt shingles continue to be the most widely installed roof covering option in north america. Find the inverse tangent of the pitch to find the angle in degrees. The minimum pitch for a roof is 1 4 12 which translates to 1 4 inch rise to 12 inches of run. The recommended minimum roof pitch for shingles is 2 12 or simply two units of vertical rise to every twelve units of horizontal span.

The minimum requirement is 2 12. They have a pitch ranging from 4 12 to 9 12. Divide the first part of the ratio by 12 to work out the pitch. Use the following formula which also describes a right triangle.

However it is regrettable that many installers usually ignore this requirement due to the desire for a quick installation process. To convert between american roofing ratios and pitch degrees follow these steps. This means if a roof rises 4 in the length of 12 your roof pitch would be 4 12 or 18 43 degrees. A ratio is the most common way of expressing roof pitch or roof slope but degrees are also possible.

On blue prints architects engineers usually display the pitch of a roof in the format shown on the image where number 4 represents a rise and number 12 represents a length. A 12 12 pitch roof has a pitch angle of 45. A shingle roof like this north dallas garage in the photo above may have a failure no matter how good a job the installer did. The short simple answer is 2 12 has traditionally been considered the absolute minimum acceptable roof slope suitable for asphalt shingles.

A 4 12 pitch is around 18 5 degrees but not exactly.