1 4 Roof Slope

Conventional from 4 12 1 in 3 to 9 12 3 in 4.

1 4 roof slope.

A 4 12 is a roof slope that rises by 4 inches for every 12 inches across. The slope of a roof or pitch is determined by how many inches the roof rises over 1 foot or 12 inches. A 3 in 12 roof rises 3 for every 12 of run. The table below shows common roof pitches and the equivalent grade degrees and radians for each.

This means that the rise of the slope goes up or down 8 inches for every 12 inches. 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. Conventional roofs are the easiest to construct and you can walk on them safely. 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.

Liquid applied roofing must have a design roof slope of 1 4 12 or greater 2 slope. These roofs have a pitch less than 4 12. 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. This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement.

An example for a steep sloped roof is 8 12. That s the same as a 14 degree slope or a 25 slope. A pitch over 9 12 is considered a steep slope roof between 2 12 and 4 12 is considered a low slope roof and less than 2 12 is considered a flat roof. Why is the roof slope 25.

You can also calculate roof pitch even without using a roof slope calculator. If the rise is 6 inches for every 12 inches of run then the roof slope is 6 in 12 the slope can be expressed numerically as a ratio. While roof slope is typically expressed in rise it can also be expressed in degrees or in percent of slope. 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.

3 of rise per 12 of run is the same as 1 of rise per 4 of run or 1 4 25. This means for every 12 horizontal units the roof must rise a minimum of one fourth vertical unit. Slope ratio a roof that rises 4 inches for every 1 foot or 12 inches of run is said to have a 4 in 12 slope. To put it in perspective the angle of this slope would be around 30 degrees.

For most home styles roof pitches fall in a range 4 12 a moderate slope up to 8 12 fairly steep. High pitched roofs often need extra fasteners and their pitch can be as high as 21 12.