How to prevent ice dams

By Allstate

Last updated: December 2023

Winter may be synonymous with picturesque snowscapes, cozy fireside moments and a fresh start in the new year. However, behind the charm of the season lies a cold reality for homeowners, especially in colder regions of the country – the potential of ice dams.

If snow blankets your rooftop and your roof’s temperature varies in certain areas, it could lead to the formation of ice dams. In this article, we’ll explain what ice dams are, what the dangers of them can be and how to prevent them. Also, we’ll discuss whether or not ice dams are usually covered by your homeowners insurance.

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What are ice dams?

An ice dam is a ridge of ice that forms at the edge of a roof and prevents melting snow and ice from draining off the roof, according to the University of Minnesota.

Are ice dams dangerous?

Ice dams are dangerous to you and your home for two main reasons. First, they can cause water and moisture to get into home which can lead to all kinds of damage. Second, they can become very heavy and pose a threat to the structural integrity of your home.

If water leaks into your home, it could cause damage to the walls, ceiling, insulation, and more. Also, unwanted moisture entering your home can lead to growth of mildew or mold, which has the potential to cause health problems, states the Environmental Protection Agency (EPA). As for the weight of ice dams, they can become quite heavy and easily tear off gutters and loosen shingles, explains This Old House.

Are icicles a sign of an ice dam on your roof?

Not necessarily, but they can be. Icicles and ice dams can appear together or separately, explains Angi. Icicles can be a sign of an ice dam higher up on the roof, or they can be present without an ice dam. Likewise, ice dams can exist without icicles being present.

How to get rid of ice dams, if you have them

If you believe that an ice dam has formed on your roof, here are three things you may want to consider:

1. Use a roof rake to remove excess snow or ice

If there are areas of your roof with a lot of ice and snow, you may want to consider removing some of it using a roof rake, says This Old House. They explain that having one with a long aluminum handle can allow you to safely stand on the ground while doing so. They also mention that having one with wheels can reduce the chances of harming your roof shingles.

Be cautious of where you stand if you’re taking this step to avoid any snow or ice from falling on you. By removing even some ice or snow, you can help speed up melting of ice dams and reduce the weight load on your roof.

2. Accelerate ice melting with calcium chloride

Calcium chloride is a compound that’s used to de-ice driveways and sidewalks, explains Bob Vila. You can also use it to help melt ice dams on your roof. However, instead of applying it directly to your roof or gutters, you should fill pantyhose or tube socks with the calcium chloride. Once you’ve filled and tied them off, you’ll want to position them vertically across any ice dams with them hanging off the roof’s edge by an inch or two. This should help create a channel for the melting water to run down and can help speed up breaking up ice dams.

Bob Vila also warns that you should never substitute calcium chloride for rock salt because it can damage your shingles and vegetation underneath the area.

3. Seal any air leaks to your attic and ventilate it

Even though it may seem counterintuitive in the winter, allowing some natural air flow through your attic will help keep it cooler, which in turn helps prevent ice dams from growing and moisture from getting inside your home, explains EnergyStar.gov.

With this approach, you don’t want the cold air from your attic entering your home. To prevent this, you can start by using spray foam to seal any visible gaps around vents or openings leading to the attic. The Department of Energy recommends that you add spray foam along the attic floor to establish a thermal boundary. They also suggest that exhaust fans (e.g., from bathrooms) be vented directly outside instead of into the attic.

Although these steps can potentially be DIY, if you feel unsure or uncomfortable doing any of them, you should consult a professional for help.

How to prevent ice dams

Some of the best protection for your roof and home from ice dams is prevention. Although there is no way to guarantee that ice dams won’t form on your roof, there are certainly a few things you can do to minimize the chance of them forming. Here are three suggestions.

1. Keep your gutters and downspouts clear

Prior to cold weather, clear out leaves, sticks and debris from your gutters and down spots to provide a channel for melting snow or ice to go, says the National Weather Service. Throughout the winter, you’ll also want to keep those same gutters and downspouts clear of snow and icicles.

2. Help control the temperature of your attic

As mentioned earlier in this article, allowing airflow into your attic will help prevent it from getting warm in certain areas, which is what typically causes ice dams to form. One of the most important ways to help airflow in the attic is by ventilating the eaves (the edge of the roof that overhangs a wall) and the roof ridges (the highest points of a roof), explains This Old House. This can be done with both ridge and soffit vents that provide at least one square foot of opening for every 300 square feet of attic floor.

This Old House also provides the following suggestions for helping control the attic temperature:

  • Insulate attic access doors. You can either use a cover or seal an existing hatch with weatherstripping.
  • Check your exhaust ducts. Make sure all ducts from bathrooms, kitchens or other living areas exhaust to the outside, not the attic. This also applies to dryer vents.
  • Add insulation in your attic floor. This can help keep the warm air inside your home and out of the attic. Most experts recommend at least an R-value of 30 (or 38 for northern climates) for attic insulation, according to the National Weather Service. Consult a reputable roofing or insulation professional for the specific type of insulation that would be right for your attic.
  • Replace older can lights with sealed ones. Older recessed lightning not only gives off a lot of heat into your attic but can also be a fire hazard with insulation above it. Make sure you replace them with sealed "IC Rated" fixtures that are safe to come in contact with insulation.
  • Check the flashing around chimneys. Over time, flashing may crack and separate from the roof, which could allow water or moisture to trickle in along the chimney. Have a chimney or roofing professional check the flashing and repair/replace it, as needed.
  • Caulk any small openings to the attic. Whether it’s around vents, pipes or electrical cables – look for any small gaps and seal around them with a fire-stop sealant.

3. Install de-icing cables

De-icing (or heat) cables are also a good way to prevent ice dams from forming on your roof and gutters, according to Family Handyman. You can install these cables along the edge of your roof, where ice dams tend to build up. Follow the manufacturer’s instructions when installing them and turn them on after heavy snowfall or when you begin to see ice forming.

Check your local hardware store to see if these are available in your area, otherwise you can purchase them online. These cables can start around $35, according to Family Handyman, and go up in price as more features are added (like ones that have sensors to turn on automatically). Also, be sure you’re thinking about where the draining water goes so that you don’t get build up of ice in other unwanted areas.

Is damage from ice dams covered by home insurance?

Usually, a homeowners insurance policy can help cover ice-related damage, including damage caused by ice dams. The Insurance Information Institute (III) explains that most types of homeowners policies do cover perils relating to the weight of ice, snow or sleet.

Your policy’s dwelling coverage may help pay for damage caused to your home, up to your coverage limit. However, personal property coverage does not typically provide protection to your personal belongings that may have been damaged as a result of an ice dam.

You’ll need to check your specific home insurance policy to learn about what protections you have in place and talk with insurer to determine whether you may benefit from additional coverage.