Ice Dams: What Indiana Homeowners Need to Know

Indiana winters are unpredictable — a warm spell followed by a hard freeze is exactly the weather pattern that creates ice dams. If you have ever seen a thick ridge of ice forming at the edge of your roof with icicles hanging below, you have seen an ice dam in progress.

Ice dams are more than an eyesore. They can force water under your shingles, saturate insulation, and cause water stains and mold in your ceilings and walls. Here is what causes them, how to prevent them, and what to do if you already have one.

Ice dams form through a specific sequence of events:

1. Snow accumulates on the roof
2. Heat escapes from the living space into the attic — through inadequate insulation or air leaks
3. The warm attic heats the roof deck, melting the snow above it
4. Meltwater runs down the roof toward the cold eaves (which are not heated by the attic)
5. The water refreezes at the eaves, forming a dam
6. More meltwater backs up behind the dam and has nowhere to go — so it seeps under shingles and into the home

The root cause is almost always a combination of inadequate attic insulation and poor attic ventilation. The fix is not on the roof — it is in the attic.

• Thick ridges of ice at the roof's edge after snowfall
• Large icicles hanging from gutters (some icicles are normal; a continuous ice ridge is not)
• Water stains on interior ceilings or walls, especially on exterior walls near the roofline
• Peeling paint on interior walls near the ceiling
• Wet or compressed attic insulation

The most effective long-term fix. The goal is to keep the attic cold — the same temperature as the outside air — so the roof deck never warms enough to melt snow.

For Indiana homes, the Department of Energy recommends R-49 to R-60 attic insulation. Many older homes have R-19 or less. Adding blown-in insulation to the attic floor is a relatively affordable upgrade that pays dividends in both ice dam prevention and year-round energy efficiency.

Insulation alone is not enough if warm air is bypassing it through gaps around light fixtures, plumbing penetrations, attic hatches, and HVAC ducts. An energy audit can identify these air leaks, which should be sealed before adding insulation.

Ventilation works alongside insulation to keep the attic cold. A properly ventilated attic draws cold outside air in through soffit vents and exhausts it through ridge or gable vents, preventing heat buildup.

If your attic has inadequate ventilation, a roofing contractor can assess and improve it — often by adding soffit vents, a ridge vent, or both.

If you are replacing your roof, specify ice and water shield (a self-adhering waterproof membrane) along the eaves and in valleys. Building code in Indiana requires it at the eaves, but extending it further up the roof provides additional protection in ice dam-prone areas.

Ice and water shield does not prevent ice dams — but it prevents the water backed up behind them from entering the home.

This is the most common mistake. Chipping ice off the roof with an axe or ice pick damages shingles and can create more leak points than the dam itself.

A long-handled roof rake (available at hardware stores) lets you pull snow off the lower portion of the roof from the ground. Removing the snow source prevents the dam from growing and allows existing ice to melt without being replenished.

Do not try to remove all the snow — just the bottom 3-4 feet near the eaves.

If water is actively backing up and entering the home, you can create channels in the ice dam to allow drainage. Fill a nylon stocking with calcium chloride ice melt (not rock salt — it damages shingles and gutters) and lay it perpendicular to the dam, extending over the edge of the roof. The melt creates a channel for water to escape.

If water is entering the home, call a roofing contractor. Temporary interior measures (catching water, drying affected areas) can prevent mold, but the roof needs professional attention to stop the source.

Once the season is over, have a roofer and/or insulation contractor assess your attic. Fixing the underlying insulation and ventilation issues is the only permanent solution.

We inspect and repair ice dam damage throughout Evansville and the Tri-State area. We also work with homeowners to identify the attic conditions that cause ice dams and recommend the right fixes. Proper attic ventilation is a key part of this — our roof ventilation guide explains how ventilation and insulation work together to protect your roof year-round.

If you had ice dam issues last winter, do not wait until next December to address them. Call us at (812) 459-2139 for a free roof inspection and honest assessment of what it will take to prevent a repeat. And when spring arrives, our spring roof checkup guide walks you through how to assess any damage ice dams may have left behind.