Ice Dams on Roofs

How to Remove Ice Dams on Roofs

By Mark J. Donovan

Ice dams on roofs damage thousands of homes every winter. Ice dams are caused by warm air in the attic melting the underside of the snow on the roof. The water from the melted snow then sheds down towards the roof eaves. The temperature at the roof eaves is much cooler, however, and as a result the water refreezes at the roof edges. As the water refreezes at the roof edges, ice dams on the roof begin to form.

Roof ice dams can become very thick, up to several inches to even a foot. Once the ice dams form, additional water from melting snow on the roof can begin to back up underneath the lower shingles.

Eventually the water finds its way into the home and down onto ceiling edges, and inside surfaces of exterior walls. Dark spots form on the ceilings and wall paint begins to bulge with trapped water. In addition, puddles begin forming on the floor.

The best defense for preventing ice dams on roofs starts back during the construction of the home. Ice and water shield, for example, should be installed along the roof edges and valleys, prior to the installation of the roof shingles.

In addition, the home builder can increase the heel height of the roof rafters or trusses over the exterior walls. By increasing the heel height, more space is available in the attic near the roof eaves for supporting additional insulation without restricting air flow from the soffit vents.

Also, the builder can extend the roof rafter or truss tails further out from the exterior walls of the home so that any water that may get up under the roof shingles will simply drip out the bottom soffit areas, and not into the home.

Use a snow rake to remove excess snow from the roof.

Moreover, the home builder can make sure there is sufficient attic insulation and ventilation so that the attic temperature stays as nearly as cold as the outside air. The colder the attic, the less likelihood of melting snow and ice dams on the roof.

Although these construction recommendations for preventing ice dams on roofs are great Monday morning quarterback suggestions, they offer little help for those who are currently dealing with roof ice dams. If ice dams already exist on your roof, you have limited options, and climbing up on your roof and hammering them off is not one of them. Chipping the ice dams will potentially punch a hole through the shingles, cause them to tear, and/or remove some of the aggregate from the shingles.

Your best solution for removing ice dams is to place long tubular socks or nylon stockings, filled with ice melt, over the ice dams and up the roof line, effectively running the stockings perpendicular to the ice dams. The socks or stockings hold in the ice melt so that it doesn’t run off too quickly from the roof. As the socks become soaked, the snow melt water becomes saturated with the ice melt, which then helps to melt channels in the ice dams for the water to drain from the roof. Place a stocking every few feet along the roof line to create a number of drainage channels in the roof ice dams.

Before applying the snow melt socks onto the ice dams you may want to remove some of the snow near the roof edge so that you can place the snow melt socks in direct contact with the ice dam surface. Use a snow rake or snow shovel to do this.

Asphalt Shingle Roofing Bid Sheet

Note that working on ladders that are in direct contact with roof ice dams and non-stable surfaces is extremely dangerous. Make sure the ladder is well anchored to the ground and that it is leaning at a sufficient enough of an angle to prevent it from kicking out on you or laterally sliding. You may also want to call in a second pair of hands to help keep the ladder stable while working on it.

As an alternative to the ice melt filled sock approach, and to avoid climbing up on ladders, you may want to look for roof-melt tables that can be tossed from the ground onto the roof. They work similar to the snow melt sock approach for removing ice dams on roofs by melting drainage channels into the ice dams.

For more help on Shingling Your Home’s Roof, see’s Asphalt Shingle Roofing Bid Sheet. The Asphalt Shingle Roofing Bid Sheet will help to ensure that your roof won’t end up with a blue tarp over it and a dumpster sitting in your yard for weeks as you wait for the roofing contractor to come back and finish roofing your home.

Asphalt Shingle Roofing Cost Estimator

Related Roofing Information

Additional Roofing Resources from


Roofing Price Quotes For FREE, No Obligation!

Fill out our 3-5 minute quick and easy form, and receive a free price quote on roofing from one of our prescreened and licensed roofing contractors. This process is free and there is no obligation to continue once you receive your roofing price estimate.