Ice Dams on Roofs

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.

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.

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.