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Helping Business Weather the Storm

How Much Snow Can Your Roof Hold?

by David Moran, on Jan 21, 2016 2:09:14 PM

When we think of hazards associated with snow, we usually think about issues such as travel issues or power outages. One serious problem often overlooked is with roofs on homes and commercial buildings, especially those with large-span installations. Do you know how much snow your roof can hold?

While the amount of weight a roof can bear depends on several variables, most can support 20 pounds per square inch of weight before becoming stressed. In areas where heavy snow is common, such as New England and the mountainous areas, roofs may be designed to support greater loads. The weight of the snow on your roof can be estimated by keeping the following guidelines in mind:

  1. 10-12 inches of new snow is equal to one inch of water (on average), or about five pounds per square inch. Keeping this in mind, a roof could support 40-48 inches of new snow before becoming stressed.
  2. If the snow is packed, 3-5 inches of snow is approximately five pounds per square inch. In this case, approximately 20 inches of snow would be the maximum amount of snow that your roof could handle.
  3. If it’s ice you’re dealing with, one inch of ice equals one foot of fresh snow.

Snow Accumulated on Cabin Roof

Melting snow generally tends to run off steeply sloped roofs (greater than 3 inches of slope in 12 inches of horizontal distance. Ice and snow tend to accumulate more quickly on roofs that are either flat or have a low slope.

If the snow load is in the range of the limits outlined above, the snow should be removed from the roof. Clearly, anticipating the snowload is a big deal for both residential and commercial large-span roofs. That's where WDT comes in with our WeatherOps product that will alert you when specific threasholds are met or are forecast to be met or exceeded. 

For a free demo of our products that can help you minimize risk and even increase your bottom line, contact us utilizing the form on the right.