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Ice Dams Cause Leaks

Ice Dams

Original Date - March 2023

As we are into Spring, we are seeing seasonal changes in the weather. Daytime temperatures are warmer, and snow is beginning to melt.

As outside temperatures increase, the problem of ice dams can occur on roofs with inadequate attic insulation.

While the outside temperature rises, heat enters the attic from within the house as the inadequate insulation allows heat into the attic space. This can also be from a poorly fitting attic hatch or heat escaping around a chimney. Another heat source can be exhaust fans which vent through soffits. 

Attics must remain calm and below-freezing this time of year. Any heat rising from the house onto the sheathing transfers the heat to the roofing material. Melting snow and water then drains to the eves. The eves are not being heated from below so the water freezes causing an ice dam. Behind the ice dam, the water pools and flow under the shingles. If no roofing membrane is installed, therefore it’s just a matter of time before water can be found inside the attic.

ice dams are caused by lack of insulation
Conclusions and Suggestions

Check in your attics for the depth of insulation in the range of 19-22 inches. Consider adding more loose fill, blown in cellulose insulation. Any shallow spots of insulation need to be filled. The insulation should be a consistent level. Check around chimneys and don’t forget the attic hatch.

Ice dams cause leaks

Ontario is considered Zone 1 and Zone 2, and the recommended R-Value is between R60 to R80. The department of Energy says that the R-Values for Loose-fill Cellulose is 3.1 – 3.8 per inch. R-60: Good Insulation, between 19 and 22 inches.

Ice Dam Research Data

Ice dam research data cannot find one single factor common to all ice dam cases. However, there were some indications of potential causes for the forming of Ice Dams – Warmer Attics.