The Advantages, Dangers of Rooftop Snow

February 10, 2013; 10:12 AM ET
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While those of us who have to deal with snow every winter may think it can be a dangerous nuisance, sometimes rooftop snow can actually benefit the home.

Naturally a household loses some of its heat from an attic but as snow piled up on a rooftop can trap this heat and keep the upper floor of the home a little bit warmer.

All that snow piled up on your roof can actually trap some of the heat that may be escaping through your attic, and help to keep the upper floor of your home a bit warmer.

In the same way, snow at ground level can act as an insulator to trap warmth from the ground, preventing it from escaping and warming the air above it. That is why temperatures tend to stay colder in areas where there is snow on the ground.

However, while rooftop snow can provide some heating advantages, it can also be extremely hazard if there's too much of it.

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.

"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.

Following a series of snowstorms in the Northeast, the roof of the WGAL Channel 8 studio in Lancaster, Pa., partially caved in due to the weight of the snow and ice on Friday, Feb. 14, 2014, according to Lancaster Online.

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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