How Much Slope For Metal Roof

Low slope roofs are not totally flat their roof slope generally ranges from 1 4 12 to 3 12.

How much slope for metal roof.

The minimum pitch for a standing seam metal roof is 1 4 or 3 inches rise to 12 inches run. The minimum pitch for roll roofing is 2 12 or 2 inches rise to 12 inches run. According to this code the minimum slope for asphalt shingles is 17 degrees or two vertical units to twelve units in the horizontal. Some slight overhang is recommended in conjunction with a drip edge flashing to prevent water from getting under the roofing and onto underlying wood.

However system manufacturers permit application on slopes of 1 4 12 or more. Standing seam metal roofs with mechanical lock systems to ward off leaks can be successfully and attractively installed on roofs with at least a slope of 1 in 12. Minimum pitch for corrugated metal roof. Metal is usually installed on rafters or strip sheathing rather than the solid decking used under other materials.

A lightweight roofing system also places fewer demands on a building s structural support system an important consideration in earthquake prone areas. Roof pitch or slope is a measure of vertical rise to horizontal run expressed in inches per foot. The pitch is measured in inches of vertical rise per foot of horizontal run and the 5v crimp profile shown above requires a minimum slope of three in twelve or 3 12 3 inches vertically per 12 inches horizontally. A typical metal roof overhang may be 2 to 4 inches or even less.

Lap sealants shall be applied in accordance with the approved manufacturer s installation instructions. In my opinion accurate slope for metal roof systems is in excess of 2 1 2 12. A steep slope allows for the fast run off of the moisture. Pitch is thus the ratio of the rise in inches to a 12 inch run and is often expressed using a semicolon for example 6 12.

Profile in the context of metal roofing means the shape that the sheet of metal is bent into to form the panels. Typically low slope metal roof systems vary in weight from 40 to 135 pounds per 100 square feet making them among the lightest roofing products and the easiest to install. Low slope metal roofs require less material which reduces the overall load on the building s structure. 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.

In case a slope greater than this is necessary then a double underlayment application must be used as per the requirements of the international building code. Low slope metal roofs have simple geometries and are easier and less expensive to install that medium to steep slope roofs.