Montana Roof Pitch Requirements

The standard of lower pitch actually ranges between 1 12 to 5 12.

Montana roof pitch requirements. With regards to the pitch the building standard code bs 5534 recommends a minimum pitch of 200 for slate roofs. Roofs between 2 12 to 4 12 pitch can use standard asphalt shingles but must have two layers of underlayment installed in the following manner. Pursuant to montana law the minimum design roof snow load after allowed reductions shall be 30 psf. Note that the state of montana requires a minimum roof snow load of 30 psf be used for design.

The minimum pitch is typically 3 12 meaning the roof should rise 3 inches for every 12 inches of horizontal foot. Minimum roof slope roof pitch r905 3 2. Montana ground snow load finder. The state of montana requires a minimum roof snow load of 30 psf be used for design 2 this minimum value applies to the final roof snow load that is calculated after all coefficients have been applied and it may be revised when justified by a design professional to the satisfaction of the building official.

Anything above that will require you to put out higher cost because they are already considered as higher pitch. Clay and concrete roof tiles can only be installed on roof slopes of 2 1 2 12 or greater. But since there is still a wide variety of slate roofing systems there are occasions when the minimum pitch can go down to as low as 15 0 depending on the uniqueness of the roof. This means for every 12 horizontal units the roof must rise a minimum of two and one half vertical units.

Class a b or c roofing shall be installed in areas designated by law as requiring their use or when the edge of the roof is less than 3 feet 914 mm from a lot line. Roofs less than 2 12 pitch cannot use standard asphalt shingles. Built up roofs shall have a design slope of a minimum of 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 a minimum one eighth unit vertical in 12 units horizontal 1 percent slope. Low slope roofing products must be used.

Roofs shall be covered with materials as set forth in sections r904 and r905. Snow loads shall be determined by the building official.