Alyssa and Jimmy, thank you for talking to me today about winter weather hazards. Winter is almost here and snow has already fallen in several states. Some people find it pretty, others annoying, but there are some real risks associated with snow. Can you tell us about them?
Snow is the most recognized type of winter precipitation. It occurs when an entire column of the atmosphere, from top to bottom, is below freezing. The accumulation of snow on street and sidewalk surfaces is what commonly causes transportation difficulties and slips, trips and falls. Clearing all that snow can be dangerous too, creating health hazards such as heart attacks, strains and sprains, and hypothermia.
Many of the property-related risks posed by snow are difficult to manage and can result in significant losses. Snow accumulations on rooftops, for example, present the potential for overloading and potential building collapse. Additional issues can be encountered when a building features parapet walls, photovoltaic arrays (solar panels) or other rooftop equipment installations. These items could result in additional load on the roof due to the effects of sliding and drifting snow. It is important to have qualified engineers verify that a roof can support additional loading.
Facilities can plan for winter weather by establishing a winter hazard control program that details the key steps to be taken during winter weather events. A snow removal plan should be included in this program to help protect a building against overloading during snowstorms. Proactive planning is critical to the protection of both property and life safety during winter weather events.
Those are good points to keep in mind. What about sleet and freezing rain? Can you describe the risks that they present?
Sleet and freezing rain, while often confused, develop differently and pose distinct hazards. Sleet (also known as ice pellets) starts as snow, melts when it hits a warm air mass as it falls through the atmosphere, refreezes when it encounters a cool layer of air and lands on the ground as frozen precipitation. The process by which sleet forms makes it less likely than snow to stick to cars, power lines and trees, but it still accumulates on the ground and poses slip, trip and fall and transportation hazards. Unlike snow, sleet is extremely dense and difficult to clear from roadways. Freezing rain is the least understood type of winter precipitation and often the most dangerous.
Freezing rain remains a super-cooled liquid throughout the atmosphere until it reaches the ground, where it freezes on contact. This can cause widespread power outages when thick coatings of ice are deposited on power lines. Trees and branches often fall due to the quick addition of weight by ice accumulations, causing major structural damage. Another danger of freezing rain is deception, where ice can occur on the ground even while air temperatures remain above freezing.
Freezing temperatures are also a threat to properties all around the country. Cold weather freeze-ups in domestic water lines and sprinkler piping present substantial exposures to property damages in the event a pipe breaks and water spreads throughout a building. Additionally, a frozen sprinkler pipe is considered an impaired fire protection system that cannot be relied upon to effectively fight a fire.
Adequate building heating systems should be provided in areas with water piping, and dry pipe sprinkler systems should be considered in areas exposed to freezing temperatures. Precaution should be taken before making alterations to building construction as this may expose pipes to freezing temperatures. Additional steps to avoid cold-weather freeze-ups include verification that heated spaces are well insulated, along with proper inspection, testing and maintenance of dry-pipe sprinkler systems. Winter weather planning should be enacted well in advance in order to help safeguard buildings from freezing temperatures.
Black ice is a winter phenomenon familiar to drivers in snow-prone areas. Alyssa, how is black ice different than freezing rain or snow?
Refreeze is a weather threat that occurs when piles of snow melt during daytime heating and freeze as temperatures cool at night, creating black ice. Typically invisible, black ice makes roads appear just “wet” and catches people by surprise.
Jimmy, driving on black ice is certainly challenging, but what risks does ice pose from a property perspective?
Ice presents a unique challenge in the protection of building structures. Accumulated snow on a rooftop that melts and then refreezes could potentially go unnoticed by building management. Frozen roof drains will prevent melting snow from escaping a rooftop. Because ice is denser than snow, its accumulation beneath snow can quickly overload a roof, leading to a building collapse. Snow removal plans should consider ice hazards and additional measures to be taken in the event ice is accumulating on a rooftop.
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