Minimum Roof Pitch For Flat Roof

Slate and slate type shingles require a minimum roof pitch of 4 12 or greater.

Minimum roof pitch for flat roof.

Typically large footprint single story warehouses and pre engineered metal buildings will utilize low slope metal roof systems. They provide excellent weather resistance great value and now more than ever a tremendous range of beautiful designs and color blends. The profile refers to the shape the metal sheets take when they bend to. This is the basis for calculating the angle which is approximately a 1 19 degree slope.

The short simple answer is 2 12 has traditionally been considered the absolute minimum acceptable roof slope suitable for asphalt shingles. Wood shakes require a minimum roof pitch of 3 12 or greater. With regards to metal roofing the profile refers to the shape adopted by the metal sheets when they are bent to form the panels. For example a roof that rises 3 inches for every 12 inches has a pitch of 3 12.

According to the international building code the typical built up flat roof that uses tar or asphalt goes by the guideline that for every foot 12 inches of a flat roof a minimum of inch must step up or down. Wood shingles require a minimum roof pitch of 3 12 or greater. Minimum pitch for metal roof. To get the minimum pitch for a metal roof the vertical rise per foot is divided by the horizontal slope.

Depending on the roof profile there are minimum roof slope requirements for each panel which need to be considered. The following table provides the minimum required allowable roof slope for each type of roofing material mentioned in the code. Mineral surfaced roll roofing requires a minimum roof pitch of 1 12 or greater. The minimum roof slope for metal roofs is dependent upon the roof profile.

To calculate roof pitch take the lowest point of the roof and measure the amount of rise for every 12 inches of horizontal movement toward the highest point. The minimum roof slope allowed by code for any type of roof is in 12 applicable only to coal tar pitch roof systems. Normally 1 80 0 72 is the recommended minimum angle for a slope and this is universal across the vast majority of flat roofing systems regardless of the materials that they incorporate. However you can only use this pitch with built up roofing or specialized synthetic roofing.

A low pitched roof is easier to put up and maintain but may show very little of its material at ground level. In order to achieve this drop a slightly steeper angle of 1 40 1 44 should be the aim when installing a flat roof as this accounts for surface. The minimum slope for standing seam of roof systems shall be one quarter unit vertical in 12 units horizontal 2 percent slope. 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.