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.

At these slopes snow creeps rather than slides and is easy to manage. 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. The slope that works best seems to be 5 12. This allows the snow to stay on while venting the roof system.

You can enter this value either as a ratio x 12 or as an angle whichever suits you better. Building a roof with wood shakes works well in moist colder climates as they don t dry out from the snow. If you live in a climate with cold winters and numerous snow storms a pitched roof will prevent the snow from remaining on the top of your home. 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.

Roof slopes lower than 4 12 tend to perform well with metal roofs which are less prone to leakage and ice dam formation. The steeper the pitch the better the snow will fall to the ground. 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. 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.