Snow load is the weight of the snow (generally reported in pounds per square foot). The weight of the snow will vary depending on its water content. Snow load on the ground can provide a rough indication of roof snow load, but roof snow loads also depend upon factors such as melting and re-freezing of snow and ice, drifting, roof slope, type of roof, and design features.
The amount of weight that a roof can safely support is based on local building code requirements and should be available within the design specifications for your building. If the structure or roof has structural deterioration, the roof might support less weight than would otherwise be expected.
• National snow load information, compiled by the
U.S. Forest Service. Includes ground snow load
information and links to state-specific data.
• National Weather Service, snow analysis data
(searchable by region, state, city, and zip code).
• U.S. Department of Agriculture, National
Resources Conservation Service, SNOwpack
TELemetry (SNOTEL) snow data for states in
the western U.S. Shows example ground snow
• For more in-depth information on roof snow load
calculations and requirements, see American
Society of Civil Engineers (ASCE) 7, Minimum
Design Loads for Buildings and Other Structures.
For more great information and safety tips check out https://www.osha.gov/Publications/OSHA-3513roof-snow-hazard.pdf