Pitch Of Roof For Snow

In general determining the pitch of an existing roof is a simple calculation.

Pitch of roof for snow.

This can be accomplished by measuring the number of inches the roof rises vertically for every 12 inches it extends horizontally. The minimum roof pitch is also subject to the standards set forth by the various building codes used in the respective regions. This is fortunate since flat roofs are somewhat more prone to leaks and require frequent inspections. If your roof is pitched enter the length and width of the flat area covered by the roof.

Importance of a roof pitch. The picture below shows the pitch of a 7 12 roof slope meaning that for 12 of horizontal measurement roof run the vertical measurement roof rise is 7. When the snow piled up on the roof melting occurred and ice dams resulted in water ponding 3 inches deep. The minimum roof pitch for shedding snow is around 30 or a 6 12 or 7 12 slope although this is not a definite as the material of your roof the direction of the snow and wind are some factors that can affect whether or not snow will slide as roofs of as little as 10 have been reported to shed snow.

The chief reason for having a roof pitch is to redirect water and snow away from the roof and avoid any percolation that might result from stagnation of water on the roof. This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement. Some metal building manufacturers will not warranty a roof with a 1 4 inch slope. A pitch over 9 12 is considered a steep slope roof between 2 12 and 4 12 is considered a low slope roof and less than 2 12 is considered a flat roof.

Metal roofs leak under these circumstances. You can enter this value either as a ratio x 12 or as an angle whichever suits you better. Low pitch roofs are easier to install and safer to walk around to complete repairs and maintenance. The table below shows common roof pitches and the equivalent grade degrees and radians for each.

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. For example a roof with a 6 inch 12 pitch is one where it rises 6 inches vertically for every 12 inches of the horizontal run. Others allow a 1 4 inch slope. In country with heavy snow and tough winter days the metal roof minimum slope is recommended to be 1 12.