Roof Slope For Snow

If your roof is pitched enter the length and width of the flat area covered by the roof.

Roof slope for snow.

Building a roof with wood shakes works well in moist colder climates as they don t dry out from the snow. In country with heavy snow and tough winter days the metal roof minimum slope is recommended to be 1 12. The steeper the pitch the better the snow will fall to the ground. This allows the snow to stay on while venting the roof system.

E 2a provided that for nonventilated warm roofs their thermal resistance r value equals or exceeds 30 ft 2 h f btu 5 3 c m 2 w and for warm ventilated roofs their r value equals or exceeds 20 ft 2 h f btu 3 5 cm 2 w. At these slopes snow creeps rather than slides and is easy to manage. You can enter this value either as a ratio x 12 or as an angle whichever suits you better. For warm roofs c t 1 0 as determined from table e 3 with an unobstructed slippery surface that will allow snow to slide off the eaves the roof slope factor c s shall be determined using the dashed line in fig.

The slope that works best seems to be 5 12. They then have the option of putting dormers on the roof without damage to the valleys penetrations lower roofs and property below due to sliding snow and ice. On roof slopes between 4 12 and 6 12 rough textured roofing materials work best. There are some opinions that standing seam metal roof minimum slope is 12 but it increases the possibility of leaking on the few first days of snow arrival.