This brief paper outlines the reasons for the countrywide survey of actual snow loads on roofs begun in 1957 by the Division of Building Research of the National Research Council. A number of examples of heavy drift load accumulations and building failures, including the collapse of the Listowel Hockey Arena, are used to emphasize the need for more realistic design snow loads in building codes. The aims of the survey are a) to determine the relation between snow loads on the ground and snow loads on roofs and b) to assess the factors that govern the accumulation of snow loads on roofs.Ce cocument indique les raisons de l'\ue9tude entreprise par la Division des recherches en b\ue2timent du conseil national de recherche \ue0 la grandeur du pa...