How an ice dam forms
- Warm atticHeat escapes from the house into the attic through gaps in insulation, recessed lights and attic hatches.
- Snow melts from belowThe warm roof deck melts the bottom of the snow, and water runs down under the snow.
- It freezes at the eaveOver the cold overhang, the water refreezes into a ridge of ice.
- Water backs upMeltwater pools behind the ridge, works under the shingles and comes in at the top of the wall or around windows.
Removing one safely
We remove ice dams with low-pressure steam, which melts channels and cuts the ice away without damaging shingles. What not to do:
- Don't chip ice with a hammer, axe or shovel. It breaks shingles and gutters.
- Don't use rock salt on the roof. It damages shingles, metal and plants.
- Don't climb an icy roof or ladder. Roof rakes from the ground are fine for pulling snow off the lower few feet.
The real fix
Stopping ice dams means keeping the roof deck cold:
Air-seal the attic floor
Seal gaps around plumbing stacks, wiring, light fixtures and the attic hatch so house heat stays in the house.
Insulate
Bring attic insulation up to current recommendations for Iowa's climate.
Ventilate
Balanced intake at the soffits and exhaust at the ridge keep the deck close to outdoor temperature. See the ventilation guide.
Ice barrier at the eaves
Self-adhering membrane under the shingles is a backstop, not a cure, and it belongs on every new roof here.
Common questions
Do heat cables work?
They can keep a channel open in a problem spot, but they use power and treat the symptom. Fixing insulation and ventilation is better.
Will gutter guards stop ice dams?
No. Ice dams form on the roof above the gutter.
Can you remove ice dams the same day?
Often, depending on demand during a cold snap. If water is coming in, tell us when you call.
