Ice Dams in Idaho: Causes & Prevention

Ice dams form when snow melts on a warm roof and refreezes at colder eaves. Water can back up under shingles and leak into decking and walls.

Why they happen

• Warm attic air + poor insulation.
• Ventilation imbalance (not enough intake/exhaust).
• Complex roof lines and north-facing areas.

What helps prevent ice dams

• Balanced ventilation.
• Proper insulation and air sealing.
• Ice & water underlayment at eaves/valleys when reroofing.

Related: Ventilation problems