Winters are shorter and warmer but come with more extreme snowfall events. Fluctuating winter conditions, excessive accumulation and even the types of snow we get now mean that buildings are faced with extraordinary snow loads that they were not originally engineered for. It can also create other hazards including ice dams, sliding snow and in snow removal practices.
Not all snow is created equal
In Canada we see everything from light fluffy flakes to heavy, wet snow. It’s important to recognize the difference because assessing snow load, or weight of the snow, depends not just on the depth of snow accumulation but also on the type of snow. For example, powder type snow is typically lighter than wet packed snow while ice is heavier than both. Snow load is determined by the total amount of all types of accumulated snow in an area and can impact buildings and the insurance you need in several ways.
Snow overloading can cause a roof to weaken or collapse and can put buildings, as well as occupants and assets, in danger. Certain roofs are also more at risk. For example, escaping heat from a building can change the consistency of the snow and a flat roof may accumulate more snow than a sloped roof. Roof additions such as solar panels and skylights can also affect a building’s capacity to handle snow load. An engineer’s assessment of the general stability of a roof and the snow load it can handle will help prevent problems as will an ongoing plan for measuring snow accumulation and removal. Some warning signs of overloading include:
- Sagging roof
- New or severe roof leaks
- Cracks in walls or masonry
- Doors or windows that are difficult to open or close
- Sounds of creaking, groaning, cracking or popping
Ice dams, formed when melted snow trickles to the outer edges of a roof and then refreezes, add to the load on your roof. This can also create additional structural problems and health hazards including mould or slip and fall conditions. Since flash thaws are common in many parts of Canada, it’s also important to ensure that water from melting snow is diverted away from foundations.
A heavy snowfall or a change in temperature can quickly send accumulated snow sliding down a sloped roof, endangering those passing by. Installing snow guards on a roof can help keep snow from falling on people, damaging lower roofs or other structures.
Snow removal is critical, but it poses a few risks of its own. Consider hiring a contractor for removal but regardless, mark off the area and take a safety-first approach to removal.
- Wait until after a snow event has ended
- Remove snow in small amounts and evenly across the roof
- Avoid creating piles of snow on a roof
- Avoid scraping snow right down to the roof – leave 5cm to avoid damaging the roof
- Avoid packing snow on the roof by walking on it
For more information, contact your insurance broker. If you don’t have one, use our Find a Broker tool.
Winter Weather. (2018). Retrieved from Insurance Bureau of Canada: http://www.ibc.ca/pe/disaster/winter-weather
Managing changing snow load risks for. (2014, December). Retrieved from Standards Council of Canada: https://nnca.ca/sites/default/files/CANCSA%20S502-14%20-%20Managing%20Changing%20Snow%20Load%20Risks%20for%20Buildings%20in%20Canada%E2%80%99s%20North.pdf