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Snow Can Cause Roofs to Collapse

Snow-related building collapses are usually caused by heavy loads of snow on roofs, so this season has been unique because of the extreme weather.  Upcoming rain and sleet will make the situation even worse, since the rain could get soaked up by the snow and add even more weight to roofs.

A cubic foot of dry snow weighs about 6 to 8 pounds, while one cubic foot of packed snow could weigh up to 20 pounds. The same volume of ice can weigh three times this amount.

Low-pitched and flat roofs are more vulnerable to snow accumulation; lower roofs are of larger risks as well.

How to calculate your roof snow load

  • Consult your local permit issuing authority to find the recorded snow load (the maximum snow expected to fall) in your region.
  • Calculate your roof pitch: Divide the "rise" (vertical distance between the peak of the roof and the edge) by the "run" (distance from the peak of your roof to the edge) and convert the fraction to a ratio of 12. (For example, if the rise of your roof is 15 feet, the run is 36 feet, then the pitch = 15 feet / 36 feet = 5:12)

How to spot problems with your building

When you see any of the following problems, contact a professional immediately

  • Sagging roofs
  • Severe roof leaks
  • Cracked or split wood members
  • Bends or ripples in supports
  • Cracks in walls or masonry
  • Sheared off screws from steel frames
  • Sprinkler heads that have dropped down below ceiling tiles
  • Doors that pop open
  • Doors or windows that are difficult to open
  • Bowed utility pipes or conduit attached at ceiling
  • Creaking, cracking or popping sounds

How to remove snow from your roof

  • Use a snow rake for pitched roofs.
  • Start from the edge to the peak of the roof.
  • Shave the snow down to 2-3 inches instead of scraping the roof clean; don't damage the shingles.
  • Plastic shovels are better than metal ones (metal tools conduct electricity and damage roofs).
  • Remove large icicles carefully.
  • Wear headgear and goggles.
  • Consider hiring a professional.
  • Have someone outside to protect you.
  • Don't add your weight or the weight of equipment to the roof.
  • Don't use a ladder since ice tends to build up on both the rungs and your shoes.
  • Don't use electric heating devices like heat guns to remove snow and ice.
  • Don't use open-flame devices to remove snow and ice.

Should you suspect a problem with your roof, we are available to inspect conditions at your building at your convenience. We specialize in forensic inspection investigations and property condition reports for commercial, industrial, municipal and residential structures.