Roofs And Winter Weather
With the Mid-Atlantic region dealing with snowstorms, the Institute for Business & Home Safety (IBHS) is offering guidance on how businesses can protect their property from winter weather-related perils, such as roof collapse due to heavy snow loads.
“Roof collapse–particularly in areas where severe winter storms are not common events–can pose major threats to people and property,” said Julie Rochman, president & CEO of IBHS. “Taking steps to prevent partial or total roof collapse can help property owners avoid costly losses.”
The snow load risk of a roof depends in large part on the age of the structure. Older roofs can suffer from corrosion of members and connections which can reduce the ability to resist high snow loads. In addition, buildings with lightweight roofs, such as metal buildings, typically have less capacity to handle a high snow load. For flat roofs, the step-down area between roof sections presents a problem due to the tendency for ice and snow collection.
The best source for determining how much snow load a building can handle is the original design plan. According to IBHS, most roof designs can support at least 20 pounds per square foot. However, design loads can range from 10 pounds to 20 pounds per square foot in Mid-Atlantic states, and between 40 pounds and 70 pounds per square foot in New England.
Guidelines to Estimate Snow Weight
- 10″ to 12″ of fresh/new snow equals about five pounds per square foot of roof space
- 3″ to 5″ of old/packed snow equals about five pounds per square foot of roof space
- Ice is much heavier, with 1″ equaling about one foot of fresh snow
Snow and Ice Removal from Roofs
IBHS recommends that property owners not attempt to climb on their roof to remove snow. A safer alternative is to use a snow rake while standing at ground level. Check your local hardware store or online stores to find snow rakes and other products that can help protect your property from the effect of snow loading.
More information from IBHS on protecting a facility against roof collapse and other winter weather-related perils can be found here.