Pitched Roof Slope Angle

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.

Pitched roof slope angle.

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. Often you express roof pitch as the ratio between the rise and the run in the form of x 12. 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.

The minimum roof pitch for shedding snow is around 30 or a 6 12 or 7 12 slope although this is not a definite as the material of your roof the direction of the snow and wind are some factors that can affect whether or not snow will slide as roofs of as little as 10 have been reported to shed snow. Thus a 4 12 pitch would be a 33 slope. This is useful because sometime you may need to cut a bevel with your circular saw that is not calibrated using roof pitch style this setting on circular saws is calibrated in degrees. Roof pitch and corresponding angles.

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. You can also divide the rise over run multiply by 100 and get a percentage. A 4 12 pitch is around 18 5 degrees but not exactly.