The paper deals with the snow
damages to roofs in Poland during last forty years, since the winter 1969/70 to
the
winter 2005/06. In the majority of cases
failures of roofs under snow loads
resulted from human errors or from the lack of appropriate structural materials
(in 1960s and 1970s). Well designed and constructed roofs were able to bear
snow load even higher than twice the design values. It was probably thank to
the overall bearing capacity of structures. Snow measurements made after the
disaster of the exhibition hall in Chorzów gave very important results.
Positive temperature of the upper layers of the ground under snow cover leads
to the melting of snow and winter maximum snow load on the ground is lower than
resulting from sum of precipitation. Well insulated flat roof will be then
loaded much more than it would be predicted. Proposals for standards of snow
loads have been presented.