Act now or those ice dams will be back
By Tim King
ONE COMMON MISUNDERSTANDING is that ice dams are caused by roof issues. The reality is that although ice dams are found on roofs, the roof itself is rarely the primary cause of the problem. For that, you need to peel back the shingles, house wrap and sheathing and look at what lies beneath your roof—your attic.
Unlike ice in your refrigerator or on a lake, ice dams are made from heat—not cold. They are created when the warm air from inside your home leaks up into the attic, heating the underside of the roof and causing the snow on the outside to melt. As the snow melts from the bottom, it then almost immediately freezes from the cold outside temperatures. What results is a system of melting and freezing that builds upon itself vertically.
On its own, the ice dam is not the problem. Its weight can be significant, although not typically enough to do much damage. Instead, it’s the damming action that the solid ridge of ice creates that leads to problems.
As normal conditions such as rising outdoor temperatures and solar radiation begin to melt the snow, the water travels down from the peak of the roof toward the ground. When the water heads down, it is stopped in its tracks by the ice dam. This not only speeds up the growth of the ice dam when the temperature falls overnight, but eventually backs up under the shingles, seeping through the wood sheathing below and into your home.
Since snow is a fact of life here in Maine, builders and homeowners can and should take steps to better insulate the areas of their attics and crawlspaces to prevent warm air from escaping into unconditioned spaces.
Creating a strong, consistent barrier between the warm air that is inside your living area and creating an open space that stays as close to the outdoor temperature as possible will ensure that whatever snow lands on your roof will stay that way, until it (slowly) melts and falls safely to the ground.
If ice dams caused you to lose sleep last winter, now is the time to do something about it. Remember, roof rakes, heat coils and metal flashing treat only the symptoms, not the cause.
Before the temperatures cool, get up into your attic (or call an insulation pro) and seal, baby, seal. You will feel the benefits all year long. The more heat that you can prevent from entering your attic this winter, the more heat you will also prevent from entering your home next summer, reducing the need for air conditioning.
This article appeared in the Fall/Winter 2021 edition of Green & Healthy Maine HOMES. Subscribe today!