Montana Roof Pitch Requirements

Anything above that will require you to put out higher cost because they are already considered as higher pitch.

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 shall be covered with materials as set forth in sections r904 and r905. 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. Minimum roof slope roof pitch r905 3 2.

Montana ground snow load finder. The minimum pitch is typically 3 12 meaning the roof should rise 3 inches for every 12 inches of horizontal foot. Snow loads shall be determined by the building official. Clay and concrete roof tiles can only be installed on roof slopes of 2 1 2 12 or greater.

This means for every 12 horizontal units the roof must rise a minimum of two and one half vertical units. Low slope roofing products must be used. Roofs less than 2 12 pitch cannot use standard asphalt shingles. The standard of lower pitch actually ranges between 1 12 to 5 12.

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. 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. In areas of the state outside of certified city county and town jurisdictions the design snow load shall be based on the ground snow loads developed in snow loads for structural design. 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. Pursuant to montana law the minimum design roof snow load after allowed reductions shall be 30 psf.