How Snow and Ice Impact Your Roof
Published On:  May 3, 2022
snow load on roof

Our Manitoba winters can be harsh, we often get large accumulations of snow.   When snow accumulates on the roof of your home, it can impact your roof in several ways.


Ice Damming

Ice dams occur when snow on your roof melts and refreezes near the edge of the roof.   Accumulated snow on the surface of the roof causes the roof to become insulated.  Heat is trapped inside the attic causing snow on the surface of the roof to melt. Water then starts to run down the roof to the roofs edge which is cooler than the rest of the roof.  The water then refreezes and can cause an ice dam to form. As more snow accumulates, the ice dam can get even larger.

If ice damming is allowed to form, it can cause damage to your shingles and could eventually result in leaks that could enter the home and cause extensive damage to the interior of your home.

Ice dams can form due to the following factors:

  • Improper Ventilation
  • Not enough attic insulation
  • Exhaust fans in bathrooms vented into the attic


Additional Stress on the roof from snow load

Accumulated snow on the roof causes extra weight on the roof.   This extra weight causes stress to the structure of your roof.  How much extra weight does snow add to the roof?   This depends on its state whether it is fresh snow, packed snow, or ice.  Fresh snow in accumulations of 10 – 12 inches can exert 5 pounds of force per square foot on the structure of the roof.  Packed snow can exert the same amount of force in smaller accumulations of 3 – 5 inches.  Just 1 inch of ice can exert the same amount of force as 12 inches of fresh snow.

These additional stresses on your roof over time can eventually cause the materials that comprise your roof to fail.  The additional stress has the potential to reduce the lifespan of your roof by several years.

How do you prevent ice damming and the additional stress on your roof from accumulated snow?


The following steps can prevent ice dams and stress on the roof from accumulated snow:

  • Remove accumulated snow from the roof with a roof rake
  • Prevent inside air from reaching the attic by sealing any leaks
  • Upgrade attic insulation and ventilation to the outside


How do you remove an existing ice dam?

You can remove an existing ice dam in one of three ways (should be performed by a roofing professional):

  • Gently run hot water over the ice dam
  • Install a heat cable
  • Remove Snow from the roof


If you aren’t comfortable performing these steps on your own, it would be wise to hire a qualified roofing contractor in your area. If you live in Manitoba, you can contact Camco Roofing Ltd for assistance resolving snow load and ice damming.   We work with commercial roofs and flat roofs in residential roofing.  Please see our contact page to reach us by phone or email or fill out our form for a free quote.

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