Ice dams and winter gutters
Summary: Ice dams form when attic heat melts roof snow that refreezes at the cold eaves; the fix is air sealing, insulation and ventilation, not new gutters. Clean gutters before winter, and consider snow bars on steep or metal roofs to keep sliding snow from tearing gutters down[2][4].
What is an ice dam?
An ice dam is a ridge of ice that forms at the edge of a roof and stops melting snow from draining off. The water backs up behind it and can leak under shingles into the walls and ceilings[1]. The cause is heat: warm air leaking from the house into the attic melts snow on the upper roof, the water runs down to the cold eaves and refreezes. The U.S. Department of Energy’s Building America Solution Center puts the fix in the attic: air-seal ceiling leaks, add insulation and ventilate[2].
Do gutters cause ice dams?
Not directly. Ice dams form on the roof edge whether there is a gutter or not. Minnesota’s energy office, in a state that sees far more of them than Indiana, notes that the fix is to stop heat loss, not to change the gutters[3]. Gutters can make damage worse, though. Packed with leaves, they hold water that freezes solid, and the weight of ice can bend hangers or pull a gutter off the fascia. Clean gutters before winter, as covered on the cleaning page.
What do snow bars do?
Snow bars, also called snow guards, are metal bars or brackets fixed on the roof above the eaves. They hold snow in place so it melts gradually instead of sliding off in one mass, which protects gutters, people and plants below. Celtic Rainwater Systems lists snow bar installation and shows snow bars fitted together with gutter guards[4]. They are most useful on metal roofs and steep slopes over walkways and entries.
How much winter weather does Indianapolis get?
Indianapolis has a cold winter with regular freezing and thawing, which is the pattern that feeds ice dams. The city’s homeowner permit guide lists a ground snow load of 20 pounds per square foot and a frost line of 30 inches for design purposes[5]. Winter months are the driest at the airport station: January averages about 3.2 inches and February about 2.6 inches of precipitation, counting snow as melted water[6].
What should a homeowner do?
- Air-seal the attic floor around lights, wiring, plumbing, ducts, chimneys and the hatch[2].
- Add insulation to the recommended depth once air leaks are sealed.
- Keep soffit vents clear so outside air can cool the roof deck.
- Clean gutters in late autumn so they are empty before freezing weather.
- Remove snow from the lower roof edge with a roof rake from the ground after heavy storms, without climbing.
- Do not chip ice off shingles; it damages the roof. Call a professional for an active leak.
See also
Common questions
Do gutter guards prevent ice dams?
No. Ice dams come from attic heat loss melting roof snow. Guards keep gutters clear but do not stop the melt-refreeze cycle.
What are snow bars?
Bars fixed above the eaves that hold snow so it melts gradually instead of sliding off and tearing down gutters.
What is the ground snow load in Indianapolis?
20 pounds per square foot, per the city’s homeowner permit guide.
References
- ^ Ice dam (roof). Wikipedia. Accessed 9 November 2026.
- ^ a b c Attic Air Sealing, Insulating, and Ventilating for Ice Dam Prevention. Building America Solution Center (PNNL, U.S. DOE). Accessed 9 November 2026.
- ^ Got ice dams? Learn what to do and how to prevent them. Minnesota Department of Commerce. Accessed 9 November 2026.
- ^ a b Gutter Installation. Celtic Rainwater Systems (celticrainwater.com). Accessed 9 November 2026.
- ^ Homeowner’s Building Permit Guide (work exempt from permitting; local design criteria). City of Indianapolis and Marion County, Department of Business and Neighborhood Services. Accessed 9 November 2026.
- ^ Global Historical Climatology Network daily (GHCNd), station USW00093819, Indianapolis International Airport. NOAA National Centers for Environmental Information. Accessed 9 November 2026.