Designing structures for snow loads

Economical structural design in deep-snow country requires an accurate prediction of ground and roof snow loads. The latest standard of the American National Standards Institute (ANSI) has focused attention on this area over the past 10 years. ANSI produced a new country-wide ground snow load map, Canada has been updating their national map, and many Western U.S. States have prescribed their local ground snow loads. The data bases used are those produced for runoff and weather predictions (i.e., SCS and NWS, respectively in the U.S.). Ground-to-roof conversion factors and data for additional considerations (e.g., ice damming, drifting, and lateral pressure) stem from studies sponsored by NRC of Canada, CRREL, NSF, and various local jurisdictions. The latest design information is being incorporated into the large building codes in the U.S. (i.e., UBC; and BOCA). Work is in progress to increase the knowledge data base, and incorporate these findings into the standards.