Ice Dam Prevention for Wisconsin Homes

What Causes Ice Dams in Wisconsin?

Ice dams are a classic Wisconsin winter problem. Madison's alternating warm and cold spells make conditions particularly prone to ice dam cycles. The mechanism is heat loss: insufficiently insulated attics allow heat from living spaces to warm the roof deck. Snow on the warm roof surface melts; meltwater runs down toward the eaves.

At the eaves, the roof is no longer over the heated building. Without heat from below, the eave drops below 32F and meltwater refreezes. Each warm-cold cycle adds to the dam. Once 3-4 inches high, meltwater pools behind it and backs under shingles, through the roof deck, and into the ceiling below.

How Much Damage Can Ice Dams Cause?

Significant. Water infiltrating under shingles saturates roof sheathing, insulation, and drywall. Ceiling staining, insulation damage, and wood rot are common outcomes. Repair costs range from $500 for ceiling patching to $5,000+ for roof deck and insulation replacement. Gutters can also be torn off by the weight of ice accumulation.

How Do You Prevent Ice Dams?

Long-term: air seal and insulate the attic to prevent heat reaching the roof deck, and ensure adequate soffit-to-ridge ventilation to keep the entire roof surface uniformly cold. Short-term: keep gutters clean so meltwater can flow freely, and use calcium chloride tubes proactively during forecast cold snaps following snowfall.