Don’t Let Heavy Snow Weigh Your Roof Down
Regular snow removal prevents collapses
To the rest of the world, it usually looks like white fluffy stuff. Nothing dangerous. If you’re a roof consultant, or a property or facility manager, you’re aware of the real danger that snow accumulation on a roof represents.
A round of excessive snowfall should put any property owner on alert – but a better approach is to remain proactive about snow accumulation. Know your baseline. The Federal Emergency Management Agency (FEMA) says a good rule of thumb is that the higher the roof’s dead load to snow load ratio, the less susceptible to collapse a structure is.
Proactive = preventative maintenance
We’ve previously written about the importance of preventative maintenance, and how you can extend the service life of your roof by fixing minor problems before they become major headaches. Those minor problems are caught by regularly scheduled inspections by a commercial roofing professional.
Inspections and preventative maintenance create the foundation of a proactive approach to the prevention of potential damage caused by snow accumulation on the roof of your building.
How much does all that snow weigh?
The official answer is that snow has a variable weight. Science uses a measurement called snow water equivalent (SWE) to express the amount of water in the snow. Fluffy and dry snow weighs about 7 pounds per cubic foot. Wet, dense snow can weigh 20 pounds or more.
Because snow weight varies, it’s difficult to accurately determine if the amount of snow on a roof is approaching a critical point. If you’d like to try measuring SWE, the National Oceanic and Atmospheric Administration’s National Weather Service offers advice on how to take accurate snow measurements.
According to CNA Insurance, rain on top of accumulated snow is especially dangerous for any kind of roof because of the potential of tripling the weight of the snow. The insurance company outlines the losses attributed to a series of winter storms that produced over 20 inches of snow in the central area of the country. Estimated losses from roof collapses exceeded $5 million for just three businesses.
The state of Minnesota knows about snow. Its university writes that the most common causes of snow build-up on a roof include:
- A 3/12 roof pitch or less prevents snow from sliding off
- Roof structures create unbalanced snow loads
- The lower level of multilevel roofs, receiving the snow from roofs above it
- Roof valleys
- Shingled roofs
Simple enough. Get up there and get the snow off the roof. If building and roof safety is your responsibility, you also know there’s more to it. It’s a hazardous effort. The Occupational Safety and Health Administration (OSHA) investigates enough serious injuries and fatalities to consider falls and other hazards to workers removing snow from rooftops to warrant a special hazard alert.
OSHA advises that the top question to be asked when making snow removal decisions is: Can snow be removed without workers going onto the roof? It’s the top consideration because, according to OSHA, falls cause most of the deaths and severe injuries that occur during snow removal operations.
As a commercial property owner or roof consultant, you also have legal responsibilities placed upon you by the State of New Jersey. Failure to abide by these regulations can lead to fines of $250 or more.
Concern for the continuation of business operations and the safety of those inside, as well as around buildings where snow has accumulated on the roof, makes it unwise to utilize anything less than professionals who specialize in commercial snow removal. They’ll use the proper equipment necessary to access the roof and properly remove the snow, so it no longer poses a threat of collapse or danger to those below.
There’s more to it than just getting it off the roof. A professional approach determines how to safely remove the snow so that the changes to the amount of weight being supported by the roof does not lead to damage or collapse.