What type of load is a snow accumulation on a roof considered to be?

Snow accumulation on a roof is classified as a static load because it is a load that does not change over time under normal conditions. Static loads are forces that are applied slowly to a structure, allowing the structure to support them without significant movement or change in position. Snow remains on the roof for a duration of time, exerting a consistent force until it melts or is removed, which aligns with the characteristics of static loads.

Dynamic loads, in contrast, involve forces that change with time, such as wind gusts or moving vehicles, which can create fluctuating stresses on a structure. An ultimate load refers to the maximum load a structure is designed to withstand, incorporating factors of safety. Non-stationary load typically implies loads that are constantly changing in magnitude and position, which does not accurately describe the nature of accumulated snow on a roof. Thus, snow should be identified as a static load due to its steady state on the structure when present.