The angle, or pitch, of a roof is calculated by the number of inches it rises vertically for every 12 inches it extends horizontally. For example, a roof that rises 6 inches for every 12 inches of horizontal run has a 6-in-12 pitch.
What is a 4/12 roof pitch?
A 4/12 is a roof slope that rises by 4 inches for every 12 inches across. 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. A 4/12 slope is enough to accommodate water runoff, but is not suitable for regions that are affected by heavy snowfall. Standard asphalt and composition shingles are the best for a 4/12 roof; rubber and wood shingles are unsuitable.
Roof Angle in Degrees to Rise-in-Run
|Convert Roof Slope from Degrees to Rise-in-Run|
|59°||19.971 in 12|
|60°||20.785 in 12|
|61°||21.649 in 12|
|62°||22.569 in 12|
Conventional slope roofs, with a pitch between 4/12 and 9/12, are the most common in residential work. Roofs with a pitch exceeding 9/12 (37 degrees) are termed steep slope roofs. In commercial work, low-slope roofs (with a pitch between 2/12 and 4/12) are most common.
Fewer snow worries: Even without a cold roof system, a steep roof is generally better in a snowy environment (which is why you see those dramatic A-frame homes in colder areas). … Ice melts more easily on a steep slope, preventing the build-up of ice patches or dams that can force moisture down into your roof.
The roof’s pitch is the angle of the roof, usually presented as the inches of vertical “rise” over 12 inches of horizontal “run.” Generally anything above a 7/12 is considered a non-walkable roof and requires some extra equipment and usually some extra cost to the customer.
Roofs in snowy climates should have a slope of at least a 10-degree pitch minimum. A steeper angled roof sheds the snow more quickly. While the angle of the roof helps shed snow, adding too many angles to the roof for a more aesthetic effect could cause structural problems with snow shedding in the wintertime
The minimum slope for lapped, non-soldered seam metal roofs without applied lap sealant shall be three units vertical in 12 units horizontal (25-percent slope). The minimum slope for lapped, non-soldered seam metal roofs with applied lap sealant shall be one-half unit vertical in 12 units horizontal (4-percent slope)
As you advance toward the top of the roof, take it one slow step a time. Many experienced roofing experts recommend walking sideways, placing both feet together with each step. When it comes time to dismount, remain crouched down just slightly as you descend.