Do gutter guards prevent ice dams?
Short answer. No. Ice dams form when heat leaking from the house warms the roof deck, melting snow that refreezes at the cold eave and backs water up under the shingles. Gutter guards sit downstream of that process; the real prevention is air sealing, insulation, ventilation, and ice and water underlayment at the eaves.
How an ice dam forms
- Snow sits on the roof.
- Warm air from the house leaks into the attic and warms the upper roof deck above freezing.
- Snow melts on the warm part of the roof and runs down.
- At the eave, which overhangs the cold outdoors, the water refreezes into a ridge of ice.
- More meltwater ponds behind the ice and works up under the shingles, leaking into walls and ceilings.
Gutters, with or without guards, are downstream of all this. A gutter packed with ice can make a dam a little bigger, but it does not cause it.
What actually prevents ice dams
- Air sealing the attic floor so warm house air does not reach the roof deck.
- Insulation at the recommended depth to keep heat in the house.
- Ventilation from soffit to ridge to keep the deck cold and even.
- Ice and water underlayment at the eaves, which seals around nails so water backed up by ice does not leak in. Whether an ice barrier is required depends on your local building department, and it is most often called for in colder north Georgia areas.
How common is this in Georgia?
Ice dams are uncommon in metro Atlanta, where snow rarely lingers, but they do happen in the north Georgia mountains and during unusual cold spells. Homes with poorly insulated attics, vaulted ceilings and leaky recessed lights are the most likely to get them. See ice and water shield in Georgia and roof ventilation basics.