Minimum Roof Slope Foam

The short simple answer is 2 12 has traditionally been considered the absolute minimum acceptable roof slope suitable for asphalt shingles.

Minimum roof slope foam.

Sprayed polyurethane foam roofs must have a design roof slope of 1 4 12 or greater 2 slope. This means for every 12 horizontal units the roof must rise a minimum of one fourth vertical unit. The metal roof minimum slope doesn t stray far from other building with different material. 18 43 asphalt shingles with special underlayment requirements 2 in 12.

For metal panel roof systems with nonsoldered seams with applied lap sealant ibc 2018 prescribes a 1 2 12 minimum roof slope. Minimum required roof slope for roofing materials. 9 46 built up roof asphalt. The minimum pitch is typically 3 12 meaning the roof should rise 3 inches for every 12 inches of horizontal foot.

The standard of lower pitch actually ranges between 1 12 to 5 12. In 12 0 25 in 12 1 19 built up roof coal tar pitch. Re roofing usually entails different slope requirements. This 1 4 12 minimum roof slope requirement also applies to spray polyurethane foam spf roof systems in new construction.

Built up roofs shall have a design slope of not less than one fourth unit vertical in 12 units horizontal 2 percent slope for drainage except for coal tar built up roofs that shall have a design slope of not less than one eighth unit vertical in 12 units horizontal 1 percent slope. Asphalt shingles continue to be the most widely installed roof covering option in north america.