Minimum Pitch For Flat Metal Roof

According to the 2012 international building code 1507 4 2 deck slope minimum slopes for roof panels need to comply with the following.

Minimum pitch for flat metal roof.

9 46 built up roof asphalt. That is a 14 degree angle. Roofing material or system. 18 43 asphalt shingles with special underlayment requirements 2 in 12.

Corrugated metal roofing has the same minimum pitch. Low slope metal roofs require less material which reduces the overall load on the building s structure. The minimum pitch for a roof is 1 4 12 which translates to 1 4 inch rise to 12 inches of run. Low slope roofs are not totally flat their roof slope generally ranges from 1 4 12 to 3 12.

That said if you want to have a metal roof that is worth its weight in value that doesn t come with a ton of problems the minimum pitch for metal roof applications should be kept at around at least a 3 1 2 12 three and a half on 12 or above. That means there is at least 3 of vertical rise to the roof slope for every 12 it goes back horizontally. Minimum metal roof slope depends on the roof profile building design climate and site location. Even though manufacturers say 1 4 12 is acceptable.

To get the minimum pitch for a metal roof the vertical rise per foot is divided by the horizontal slope. In retrofit projects a sub framing system is attached to the existing flat roof surface to provide a minimum 12 roof pitch. Minimum required slope x in 12 minimum required slope degrees asphalt shingles. Low slope metal roofs have simple geometries and are easier and less expensive to install that medium to steep slope roofs.

Moreover low slope metal roofs are not prone to the degradation experienced by organic materials enabling these roofs to better resist the elements. 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. Most residential metal roofs require at least a 3 12 roof pitch and have no maximum roof pitch. 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.

However you can only use this pitch with built up roofing or specialized synthetic roofing.