The Science of Experience



How Ice Dams Can Damage Your Home

Posted by Becky Eades

Dec 29, 2015 11:30:00 AM

Snow and cold are impossible to avoid in the winter, so it's important to make sure your home is built to withstand them. One of the ways in which the cold weather can threaten your home is through the formation of ice dams. Ice dams may sound harmless enough, but they can actually cause costly and long-lasting damage to your roof, insulation, and even your ceilings and walls.


image via Paul VanDerWerf

What are ice dams?

Ice dams are layers of ice that can build up on the edge of your home's roof. They occur when snow melts on your roof, and the water trickles down to the roof's edge before refreezing. Once there is an ice dam in place, it continues to grow larger and larger, since additional water gets trapped behind it.

How do ice dams cause damage?

As ice dams grow larger, they begin to work their way under shingles, causing damage to your roof. When your shingles become loosened by the ice, water can trickle down into your insulation, eventually soaking your walls and leading to mold formation.

How can ice dams be prevented?

The key to preventing ice dams is keeping your roof cool, and that can only be done through proper insulation. In areas with cold winters, you'll typically need insulation with an R-value of at least 38. You should also make sure there are no air leaks around vents, chimneys or wiring. Polyurethane spray foam insulation is a good choice because it has a high R-value and seals cracks and crevices completely. A well insulated attic prevents heat from escaping through the roof and melting the snow.

If you have ice dams, be sure to add insulation to your attic before damage occurs. Visit NCFI's website to find a polyurethane spray foam insulation applicator in your area.

Topics: Safety, Winter