How to Prevent and Remove Ice Dams from Your Roof

Ice dams form when snow that has accumulated on the roof melts and runs down to the gutter system. As the meltwater runs into the gutter system, it cools and begins to freeze. Gradually, ice builds up in the gutter, forming an ice dam. When this occurs, the weight of the ice can damage the gutter system.

Additionally, the ice dam prevents water from draining away from the home, causing water to seep through the shingles, where it freezes, expands, and ultimately loosens the shingles. Once this happens, the water can work its way into the roof, causing extensive water damage, wood rot, and mold growth. Here's how to prevent and remove ice dams from your roof.

What Is an Ice Dam and How Do They Form?

An ice dam is essentially a block of ice that forms in the gutter system of the home. As it grows, it prevents the gutter system from draining water away from the house. It can also damage the roof, put excessive weight on the gutter system, and lead to water damage and wood rot.

Ice dams form because of a difference in temperature between the roof and the eaves. Usually, a third of all heat that escapes from the home passes through the attic before exiting through the roof. This heat increases the temperature of the roof, causing the snow to melt. However, the temperature of the eaves is typically lower than the roof's temperature, so the meltwater flows into the eaves and freezes, gradually building to the point of becoming an ice dam.

If there is a significant temperature difference between the roof and the eaves, ice damming will likely occur. The greater the difference, the higher the chance of ice dam formation. With this in mind, learning how to prevent and remove ice dams is important.

Safety Considerations

When dealing with an existing ice dam, DIYers and professionals must be careful to avoid damaging the roof or being injured during removal.

The person breaking up the ice dam should work from a safe vantage point on the roof, ensuring they are securely connected to fall-arrest equipment to prevent injury if they slip or trip. Additionally, DIYers should never substitute rock salt for calcium chloride when melting the ice dam. While calcium chloride is safe for roof shingles and vegetation, rock salt poses a risk to the home and plant life.

3 Ways to Remove Ice Dams

1. Melt Ice Dams with Calcium Chloride

Using a chemical compound to melt ice dams is an excellent way to remove this problem, though it's essential to find products that are safe for use on shingles and around vegetation. With this in mind, the DIYer should never use rock salt for this purpose. Instead, use calcium chloride or a similar ice-melting product.

Fill a long tube sock or pantyhose legging with calcium chloride, tie off the ends with string, and hang each sock over the dam. You can use a roof rake or a similar tool to position the sock to hang an inch or two over the roof edge. As the calcium chloride melts the ice, it creates a channel through the dam, allowing any additional water to flow freely. However, the channels may fill up quickly if there is further snowfall in the following days, so it's important to keep the roof clear of snow with a roof rake while the ice dam is melting.

2. Melt Ice Dams with Hot Water or Steam

Hot water is one of the best ways to remove an ice dam. There is little risk of the water harming the vegetation or roofing shingles, but this process can take a while for a DIYer to complete. Start by connecting a garden hose to the hot water outlet for the laundry tub or washing machine. Carry the garden hose up to the ice dam and begin gradually melting the ice dam with the hot water. Avoid directing the pressurized water directly against the shingles, as this can cause the shingles to lift and pull away from the roof.

Homeowners can hire professionals to melt the ice dam with hot water or by using commercial steaming equipment. Pros have the knowledge and experience to eliminate the ice dam quickly and efficiently while following detailed safety protocols to avoid injury.

3. Break Up the Ice Dam

While it is possible to physically break up an ice dam by carefully using a mallet and chisel, this method is significantly more dangerous than attempting to melt the ice dam. This method isn't suggested for DIYers because they may damage the roof or gutter system while banging away with a hammer, leading to more problems in the future. Additionally, breaking an ice dam can cause large icicles, sheets of ice, and chunks of ice to slide or drop from the roof, putting the DIYer and anyone nearby at risk.

If breaking up the ice dam seems like the best option, then it's best to call a professional crew to handle the job. Pros have the experience, skills, and proper tools readily available to tackle this type of work, so there is less risk of injury or damage to the property.

How to Prevent Ice Dams

Rake Snow Off the Roof

One of the best ways to stop ice from forming on a driveway is to shovel the driveway after it snows. Similarly, DIYers can prevent ice dams from forming by removing the snow from the roof. If no snow is on the roof, it can't melt and create ice dams.

Use a lightweight roof rake with a long extension to safely rake snow off the roof. Ideally, the extension will be long enough for the DIYer to work from the ground while remaining far enough away from the home to avoid the snow and ice as it is pulled off the roof. After removing the snow, climb to the eaves and clear any leaves or branches that may have accumulated in the gutter system.

Seal Airflow Leaks and Ventilate the Attic

Heat from the home that escapes through gaps around the soffits, intake vents, or flashing can cause the snow on the roof to melt and form ice dams. DIYers can reduce the amount of heat flowing to the roof by sealing these gaps. Similarly, you can reroute bathroom vents or dryer vents so that they exit through an exterior wall instead of through the attic.

Homeowners may also install attic vents along the underside of the eaves to ventilate the attic, releasing warm air through the attic vents before it builds up directly under the roof. Installing an efficient ventilation system for the home is a job for a professional.

Install Attic Insulation

The heat transfer through the roof and into the snow causes the snow to melt and flow down toward the gutter system, where it freezes and creates ice dams. By installing attic insulation, the homeowner can reduce the transfer of heat through the roof, slowing the rate at which the snow melts. Not only does this help prevent ice dams, but it also improves the efficiency of the home. However, attics require proper ventilation to avoid moisture accumulation, so to avoid accidentally hampering the ventilation of the attic, it's best to leave this job to a professional.

Add Heated De-Icing Cables

A great way to prevent ice dams is to install heated de-icing cables. These cables are designed specifically to prevent ice from forming on the roof and in the gutter systems. DIYers or professionals can install these cables by running the cables through the gutters and up to the roof. Secure the cables using the fasteners provided by the manufacturer and plug in the cables at an exterior power outlet to heat the gutters and roof.

Keep in mind that this option should only be used if the roof is currently clear of snow and ice. Also, it's imperative to find de-icing cables specifically made for roof and gutter installation. Additionally, the DIYer must work carefully to avoid damaging the cables when raking snow off the roof.

When to Call a Professional

Ice dams can be problematic due to the location in which they form and the persistent freezing created by snow and meltwater. DIYers who are uncomfortable climbing a ladder or working on the roof in slippery conditions should contact a professional to remove existing ice dams and install preventive systems, like de-icing cables.

Additionally, some aspects of ice dam prevention are best left to the pros, including installing attic insulation, sealing airflow leaks, rerouting home ventilation, and adding attic vents to improve attic ventilation. Most homeowners benefit from hiring professionals to melt ice dams with steam or physically break up ice dams.