Ice Dams: Why They Happen in Southern Wisconsin
Ice dams are the #1 cause of interior water damage for Madison homeowners during winter. They form when heat escaping from your attic melts snow on the upper part of the roof. That meltwater flows downhill until it reaches the cold eave overhang, where it refreezes into a ridge of ice that traps water behind it.
Madison's position on the Isthmus between Lakes Mendota and Monona creates unique conditions. The lake-effect moisture combined with freeze-thaw cycles that can swing 30°F in a single day make our area especially vulnerable. Homes in the near-west side, Shorewood Hills, and Maple Bluff — where mature tree canopy shades parts of the roof unevenly — are particularly at risk.
Our prevention strategy: Exceeding Madison Code: We install Ice & Water membranes extending 24" past the interior wall line (SPS 321.28) to eliminate ice dam leaks along all eaves, valleys, and around penetrations. Combined with proper attic insulation and ventilation, this eliminates the conditions that cause ice dams in the first place.


