Snow load

Snow Loads

Excessive ice and snow loads can overload a buildings structural members and sometimes even cause a roof collapse. Excessive snow loads are usually the result of wind creating large snow drifts. Snow drifts can create concentrated loads on roofs that are well in excess of the loads imposed by uniformly distributed snow. Winter rain storms and ice buildup can further increase roof loads.

The New York State building code did not even consider snow drifting; and therefore, most buildings were not designed for this possibility. Fortunately, few roof failures occur without warning signs. Example, In one school a laminated wood beam broke with such force that security personnel reported hearing what sounded like a gun shot. Warning signs of structural roof problems include roof leaks, cracks in walls and ceilings, and excessive sagging of structural roof elements or ceilings. Hung ceilings often hide the roof structure but will sag if the roof has excessively deflected. Signs of structural roof problems are usually more visible during periods of heavy snow loads.

The roofs of older buildings which have been reinsulated for energy conservation must also be re-evaluated to make sure they can handle additional loads of accumulated snow. Added insulation may increase the probability that more snow stays on the roof longer, thereby increasing snow loads when there are multiple storms. Replacing a non-ballasted roof with a ballasted roof also may reduce the snow load carrying capacity.




Damages to Springfield and Baca County from the large amount of snow fall which causes loss of livestock has been around 10,000.   The figure below shown the roof and the crack in the front of the building caused by snow storm. The front windows were all broken too.

 Snow storm damage the whole structure of building.

 Structure damages by ice dam and snow load

Based on the structural design of a building, snow loads can be a serious concern during the winter. Places where snow loads should be of concern:

• Roof Overhangs
• Multilevel Roofs
• Valleys

Structural integrity is also something to be concerned about. Years of wear and tear of existing structures and their exposure to water and weight can cause rotting, in turn making them weak.

Two means of solving excessive snow load problems are:

• to reinforce roof areas to handle large potential snow accumulation, or
• to remove the snow to maintain snow loads at acceptable limits.

If buildings are showing any signs of structural overloading, an architect or structural engineer should be consulted. Repeated overloading of roofs can significantly weaken the roof structure over time.