Standard Roof Slope Angle

You can assess this in two ways either as the roof pitch angles which the rafters make with the horizontal or the proportion between the run and the rise of the roof.

Standard roof slope angle.

To do this simply convert the rise and run as a fraction to a decimal form eg. 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. Two most common methods 4 12 or 4 12 are used for marking the pitch of a roof. If we consider the commercial applications then low sloop type roofs are preferred with pitch ranging from 2 12 to 4 12.

Some sources consider low slope to include 3 12 pitch roofs. The 12 inch run is considered standard in roof pitch or angle terminologies. First convert the pitch to a slope. So use the 12 inch level as a constant run and 18 inch ruler as a variable rise.

A ratio is the most common way of expressing roof pitch or roof slope but degrees are also possible. See low slope roofing. This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement. In the roofing trade the go to term is pitch and it is expressed in terms of 12 inches so the pitch of a roof is determined by how many inches the slope rises for every 12 inches it runs horizontally.

If asphalt shingles are to be installed on a low slope roof special steps are required to avoid short roof life and roof leaks. Pitch angle incline slope they all can be used to refer to the steepness of a roof. Pitches of less than 2 12 are considered flat roofs even though they may be very slightly angled. Locate its tangent or tan and follow the left row for you to read its corresponding degree.

Rise run rise run slope. Pitches above 9 12 are very highly angled and are designated steep slope roofs. Often you express roof pitch as the ratio between the rise and the run in the form of x 12. The most commonly used roof pitches fall in a range between 4 12 and 9 12.

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. Low slope roofs are from 0 to 3 12 in pitch. Pitches lower than 4 12 have a slight angle and they are defined as low slope roofs. The way pitch also known as roof slope is measured is rise over run.

The combination of two numbers are used to display or show the roof pitch. Roof pitch refers to the slope which the rafter creates. This means if a roof rises 4 in the length of 12 your roof pitch would be 4 12 or 18 43 degrees. 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.