Montana Roof Pitch Requirements

Clay and concrete roof tiles can only be installed on roof slopes of 2 1 2 12 or greater.

Montana roof pitch requirements.

Pursuant to montana law the minimum design roof snow load after allowed reductions shall be 30 psf. Minimum roof slope roof pitch r905 3 2. Roofs shall be covered with materials as set forth in sections r904 and r905. Roofs less than 2 12 pitch cannot use standard asphalt shingles.

Anything above that will require you to put out higher cost because they are already considered as higher pitch. 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. Low slope roofing products must be used. Snow loads shall be determined by the building official.

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. 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. Montana ground snow load finder. Apply a 19 inch strip of underlayment felt on top of the ice barrier parallel to.

Local and or state requirements on the ground snow loads or the roof loads subsequently calculated from these values supercede the values provided by this snow load finder tool. The minimum pitch is typically 3 12 meaning the roof should rise 3 inches for every 12 inches of horizontal foot. This means for every 12 horizontal units the roof must rise a minimum of two and one half vertical units. Note that the state of montana requires a minimum roof snow load of 30 psf be used for design.

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