Home › Guides › Outdoor & seasonal › How to prevent ice dams (and what to do if you have one)
GuideIce dams — those ridges of ice at the edge of a roof — look harmless but cause some of the most expensive winter roof and water damage. The good news is they're largely preventable once you understand what causes them. Here's how to stop ice dams and what to do if one's already formed.
Ice dams form when heat escaping into the attic warms the roof, melting snow that then refreezes at the cold roof edge and gutters. The dam traps more meltwater behind it, which backs up under shingles and leaks into the home. The root cause is almost always heat loss into the attic plus poor ventilation — not just cold weather.
Water backing up behind an ice dam seeps under shingles and into the roof deck, attic, insulation, walls and ceilings — causing stains, rot, soaked insulation and mould. The gutters and roof edge can also be damaged by the weight of ice. It's a quietly expensive problem that shows up as interior water damage.
The real fix is keeping the roof cold: seal air leaks from the living space into the attic, add attic insulation so heat doesn't warm the roof, and ensure proper attic ventilation so the roof stays an even temperature. This is the permanent solution — it addresses the heat loss that causes dams in the first place.
Keep gutters clean in fall so meltwater can drain, and after heavy snowfall, carefully raking snow off the lower roof edge with a roof rake (from the ground) reduces the snow available to melt and refreeze. Don't climb onto an icy roof — that's dangerous.
Don't chip at the ice (you'll damage the roof) or climb up in icy conditions. For an active leak, you can carefully clear snow from the roof edge from the ground and improve attic conditions, but a significant ice dam or interior leak is a job for a pro who can safely remove it and address the cause. Then fix the insulation and ventilation so it doesn't return.
Preventing ice dams for good means attic insulation, air sealing and ventilation — plus fall gutter cleaning and roof checks. On Genie you can book insulation, gutter cleaning, and roof work with vetted, insured pros, so you solve the cause rather than fighting the ice every winter.
Every task in this guide is something you can book on Genie — vetted, insured pros at an upfront price:
Heat escaping into the attic warms the roof and melts snow, which refreezes at the cold roof edge. The dam traps meltwater that backs up under shingles and leaks inside. The root cause is attic heat loss and poor ventilation.
Keep the roof cold: seal attic air leaks, add insulation, and ensure proper attic ventilation. Also clean gutters in fall and rake snow off the lower roof edge from the ground after heavy snowfall.
Don't chip at the ice or climb an icy roof. Clear snow from the edge from the ground if you can, and for a significant dam or active leak, get a pro to remove it safely and fix the insulation and ventilation causing it.
