How Do Ice Dams Form?


If you live in Wisconsin, chances are you already know what an ice dam is. But, you may not know the science behind how ice dams form. Read on to learn about how different components of your home, such as your roof, your gutters, and the insulation in your attic may be contributing to the formation of ice dams.

How Do Ice Dams Form

The Conditions

For an ice dam to form, there are certain conditions that need to be in place. For starters, there must be snow on your roof and the exterior temperature needs to be below 32 degrees F. If this is the case, the eaves of your roof (nearest the gutters) will be 32 degrees or colder. However, because you’ll undoubtedly be running the heat in your home, and heat rises, the portion of your roof nearest the ridge will be warming up. When this happens, the snow melts and begins to run down the roof, but then freezes again when it reaches the eave.

The Consequences

If this happens for a long enough period of time, a lip of ice will form along the eave, ultimately preventing any other melting snow or rainwater that runs down from flowing off your roof. If there is enough precipitation, a significant amount of water can collect behind these ice dams, and can ultimately leak inside your home, damaging your roof, ceiling, walls, insulation, and more.


In order to stop ice dams from forming, you should ensure that you have adequate insulation in your attic. This will stop your roof from warming up too much and letting the snow melt. Also, if your gutter system is prone to clogging, it may collect a significant amount of runoff and freeze, contributing to ice dam formation. If this is the case, it’s advisable to have your gutters thoroughly cleaned, repaired, or replaced.

Partner with Frey Construction for Expert Service

For more information about how ice dams typically form, and what you can do to prevent them from forming along your home, contact the experts at Frey Construction. Since 1995, we’ve helped homeowners throughout the Madison, Wisconsin, area by making home improvement Quick & Painless.

Contact us today to schedule a complimentary, at-home consultation.