How to prevent ice dams

By Allstate

Last updated: January 1

Perhaps you saw them around the holidays: white or blue outdoor lights that simulate sparkling icicles. Or maybe they were on holiday card, hanging from the eaves of a picturesque house. While icicles often look pretty, they may actually cause a lot of trouble for your home.

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Are icicles a sign something is amiss?

Icicles are commonly thought to be a sign of an ice dam on your roof, but are they? Possibly, says Focus on Energy.

The three things necessary to form icicles — snow, heat to melt the snow and cold weather — are also needed to form ice dams, Focus on Energy explains. Ice dams form when warm air from inside your home melts snow on the roof. When the meltwater reaches the colder eaves (the part of the roof that extends beyond the walls), the water refreezes and creates a buildup of ice along the edge of your roofline, says This Old House.

So, icicles hanging from a roof's edge may be a sign of an ice dam. However, ice dams can form without the presence of any large icicles.

What are the dangers of ice dams?

The more snow and ice accumulate, and temperatures rise and fall, the larger the potential for ice dams. And ice dams can cause a lot of damage both inside and outside of your home. You may see damage on your roof and gutters and this may lead to meltwater getting into your ceiling or attic, says the Insurance Information Institute. Once that happens, insulation may get wet, paint may peel and the structure of your home may become damp, says Focus on Energy.

How to remove snow to help avoid an ice dam

It's best to remove snow from a heavy snowfall immediately to help prevent the buildup of ice dams later. Though you might hear about people doing anything from using a snow blower to remove snow or an axe to help chip away at an already-formed ice dam, both methods may damage your roof. These methods may also be dangerous to your own personal safety, warns.

A push broom with stiff bristles can be used to help remove snow off flat and low-slope roofs, while a roof rake can be the right option for sloped roofs, the National Weather Service says, because you can remain on the ground and still remove snow. Of course, you can also contact a professional to do the job.

In the event that an ice dam does form, the weather service suggests keeping the attic well ventilated — the colder the attic, the less melting and refreezing on your roof, the weather service says.

How to help prevent ice dams in the future

According to This Old House, a simple way to help prevent ice dams is to keep your roof and eaves the same temperature. Here's how:

  • Add extra insulation in your attic floor to help keep the warm air inside your home and out of the attic.
  • Relocate or remove heat sources (recessed lighting, for instance) in the attic directly under your roof.
  • Insulate attic access doors with a cover, or seal an existing hatch with weatherstripping.
  • Check the exhausts. Make sure all ducts from bathrooms, kitchens or other living areas exhaust to the outside, not the attic.
  • Check the flashing around the chimney. Over time, the flashing may crack and separate from the roof, causing hot air to potentially escape and allowing water to trickle in along the chimney. Have your chimney or roofing professional check the flashing and, if necessary, repair or replace it.

Preventive steps like these can help preserve the health of your home by stopping ice dams — and maybe even those icicles!