Minimum Slope For Flat Roof

Minimum roof slope roof pitch r905 4 2 metal roof shingles can only be installed on roof slopes of 3 12 or greater 25 slope.

Minimum slope for flat roof.

It takes the manufacturer s recommendations the unique conditions of the roof as well as the skills and the expertise of the installer to arrive at the right slope. The following table provides the minimum required allowable roof slope for each type of roofing material mentioned in the code. In general the minimum slope for a flat roof is 1 0 but as stated earlier this is only possible in theory. The minimum roof slope allowed by code for any type of roof is in 12 applicable only to coal tar pitch roof systems.

For example the international building code 2018 edition ibc 2018 prescribes a 1 4 12 minimum roof slope for asphalt built up polymer modified bitumen thermoset and thermoplastic single ply and liquid applied membranes in new construction. 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. Flat roof slope minimum 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. This means for every 12 horizontal units the roof must rise a minimum of 3 vertical units.

This is the basis for calculating the angle which is approximately a 1 19 degree slope.