Designing Structures for Snow Loads

Abstract

Historical information, research results, and codes/standards provide the basis for a profile of snow load design practices in North America. Canada prescribes 30‐year mean recurrence interval (mri) ground snow using a Gumbel distribution, whereas the United States is adopting 50‐year mri ground snow modeled with a lognormal distribution. Ground‐to‐roof conversion factors are described with reference to the Canadian studies (1956–1967) and the nation‐wide measurements used in writing the 1982 standard for American National Standards Institute. Various field investigations revealed the effects on roof snow accumulations of roof exposure to wind and sun, roof geometry, roof cladding, and building thermal losses. We describe similarities in the three major model building codes, plus standards, in the United States, and the code of Canadian. Critical research needs on snow loads are also explained.