What Are Ice Dams?

Winter brings one of your home’s worst enemies — ice dams. Here's how to keep them from forming and damaging your roof.

Ice dams occur after a heavy snowfall when warm air in the attic heats up the roof and melts the snow. Water running down the roof refreezes when it reaches the colder roof edge, forming a mound of ice.

What Damage Can Ice Dams Cause?

Ice dams begin as continuous chunks of ice that form along the margins of your roof. While frozen, they’re no more trouble than the icicles that hang down from them. But during the warmer parts of a winter day, water melting off the roof can pool behind the ice. If it’s got nowhere else to go, it seeps back up under the shingles.

Sometimes water works its way five or even ten feet back up under the shingles. Eventually, it drips through the roof into the soffits (the outside overhangs), walls and, worst of all, onto your ceilings. You’ll first see ice dam rust spots on drywall fasteners. Then you’ll perhaps see peeling paint, sagging drywall and stains around windows and doors. Eventually, you may even get mold or rot.

Insurance companies pay millions of dollars annually to homeowners to repair the damage. But it’s never enough to cover the time and aggravation of getting everything fixed.

How to Prevent Ice Dams

The best time to stop ice dams is before winter comes and before they build up. Properly winterizing your house will go a long way toward preventing ice dams.

Start by maintaining your roof. Damaged shingles and plugged gutters make it easier for water to sneak into your roof, so fixing them now will save you time and money down the road. While you’re at it, lay down heat cables to help water flow off your roof instead of under it.

Stay away from the salt-filled pantyhose hack. It won’t stop ice dams but it might discolor your roof.

Getting Rid of Ice Dams

If you already have ice dams, there are some ways to prevent lasting damage. It’s difficult to get rid of ice dams altogether, but there are many ways to prevent them from growing. When kept small enough, ice dams often melt naturally without damaging your home.

Buy a roof rake to remove excess snow before it melts. Keep your attic cold to stop water from melting into it. And make sure your gutters are clear. If your ice dams are severe, consider hiring a professional to remove them.