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National Snow Load Information

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Ice Dam and Snow Conditions

These are photos of ice dams and sliding snow conditions on National Park Service buildings. Photographs were taken by Andy Beck, Architect, National Park Service, United States Department of the Interior.

Photo of a snow covered house with a severe ice dam on the right side roof.
This photo depicts a severe ice dam on the right side of the house
near the bottom edge of the roof. You can see snow movement down
the roof of the building, which causes snow buildup at the eaves.
Notice that the porch remains cold; therefore, there is no snow slide
or ice dam over the porch.

Photo of the side of a building with icicles hanging down from the roof.
Photo of a snow-covered house with large icicles hanging from
the roof, which demonstrates the effects of uncontrolled drainage.
The hot roof on this building has caused an ice dam, snow buildup,
and piles of uncontrolled snow on the ground. Doors and windows
are blocked. When the snow melts, the walls will get soaked.

Photo of a snow-covered house with ice dam building on the upper roof and icicles hanging from the roof edges
This photo demonstrates a classic poor building design for snow country.
The steep-pitched, hot roof that drains onto lower roofs is a disaster
in action. There is ice dam buildup on the upper roof, and a subsequent
dumping of extra load on the lower roof. It is likely that the roof
leaks and that the building is overstressed all winter long.