The Dangers of Rooftop Snow

November 20, 2014; 11:07 AM ET
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AccuWeather.com

Though a small amount of rooftop snow can act as an insulator during cold winter months, an excessive amount can cause structural damage to your home or result in a total roof collapse.

Determining how much snow is too much snow, depends on the shape and age of the rooftop.

If a roof is pitched or slanted, and in fairly good condition, heavier snow may be less of a problem. However, older and more flat roofs could easily succumb to the weight of the snow and fail.

Mark Settlemyer, left, gets help clearing snow from the roof of his mother's house from Ken Wesley on Wednesday, Nov. 19, 2014, in Lancaster, N.Y. Lake-effect snow pummeled areas around Buffalo for a second straight day, leaving residents stuck in their homes as officials tried to clear massive snow mounds with another storm looming. (AP Photo/Mike Groll)

"As snow sits on roofs, especially flat ones, it compacts and becomes more dense," AccuWeather Meteorologist Mark Paquette said. "When snow and ice falls on it, it becomes heavier."

A cold rain can also lead to heavier snow and more weight on a rooftop because when the rain falls it is then absorbed by snow already on the rooftop. As a result, the snow becomes even heavier than it was before the rain.

If the snow becomes too heavy, it can weaken the internal structure of a roof and cause damage or even cause the roof to completely collapse.

The type of snow that falls can also contribute to the likeliness of a roof collapse.

"There are different types of snow as well that can cause various damage," Paquette said. "A lighter, fluffier snow that falls with cold temperatures is a much different story than a wet, heavy snow with sleet and rain."

The more dangerous type of snow is the wetter, heavier snow due to its increased water content. This type of snow is most common around areas in southern New England.

To prevent a roof collapse or damage due to snowfall, keep tools handy that allow for timely and easy snow removal after a storm.

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