A 4 12 is a roof slope that rises by 4 inches for every 12 inches across.
Roof slope pitch angle.
Rise run rise run slope.
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.
First convert the pitch to a slope.
Two most common methods 4 12 or 4 12 are used for marking the pitch of a roof.
This is very useful information for many purposes especially for roof framing the slope sometimes called pitch is calibrated on speed squares.
Often you express roof pitch as the ratio between the rise and the run in the form of x 12.
To find the angle of a roof in degrees convert the pitch to a slope then convert to degrees by finding the arc tangent of the slope.
Roof pitch refers to the slope which the rafter creates.
This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement.
Roof pitch angle and slope factor charts.
To do this simply convert the rise and run as a fraction to a decimal form eg.
This forms an angle of 18 5 between the horizontal section and the roof and creates a gentle incline that is seen as a midpoint between a low pitch and medium pitch roof.
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.
Angle the angle of a roof is the same as the roof s slope except instead of being represented as x 12 it is represented in degrees.