What type of load is typically due to snow accumulation on a roof?

Snow accumulation on a roof is considered a dead load. Dead loads are static forces that are always present and do not change significantly over time. They typically include the weight of the structure itself, any permanent fixtures, and materials that are not subject to change, such as snow that accumulates during winter months.

In the context of roofing systems, the snow introduces a consistent weight that the structure must support until it melts or is removed. Since this weight does not vary rapidly like other loads might (such as vehicles moving on a bridge or people walking in and out of a building), it is classified as a dead load.

Other types of loads mentioned in the options contribute to the understanding of structural dynamics, but they do not apply to the situation with snow. Live loads, for instance, refer to transient forces that change over time, like people or furniture in a building. Impact loads represent sudden forces resulting from high-speed events, such as a vehicle crashing into a wall, while dynamic loads involve forces that can vary in magnitude and direction, such as wind or seismic events. However, none of these accurately describe the stable and consistent nature of snow accumulation on a roof.