A Roof Leak Caused by an Ice Dam

Ice Dam Symptoms

• Ice dams are buildups of ice on a roof that "dam" up the flow of melting water along the roof, preventing the water from running off to the ground. Ice dams along the eave of a roof can be identified through visual inspection, as they will present a large barrier of solid ice along the roof line. Large groups of unusually large icicles along the eave of a home indicate the presence of an ice dam. Ice dams may form higher up on the roof as well, and can be difficult to diagnose, as they are often hidden beneath a blanket of snow. Any exposed surface of an ice dam may be seen by shining a flashlight over the roof after dark. Ice dams will appear much more reflective than the snow surrounding them.

Causes of Ice Dams

• Ice dams form due to differing surface temperatures along a roof. Warmer areas at higher roof elevations allow accumulated snow to melt. The resulting water flows down the surface of the roof and refreezes when it encounters a surface below 32 degrees Fahrenheit. Ice begins to accumulate along the colder roof surface as the snow continues to melt above it. Eventually, a large enough ridge of ice will form, preventing any more melting snow from running off the roof. The residual water backs up along the surface of the roof, causing leaks.

Preventing Ice Dams

• Preventing ice dams before they form is the most effective way to prevent associated leaks. Areas of heat loss along the roof can be identified by the absence of snow or faster melting of snow. The attic area directly below these heat loss centers should be properly insulated to prevent the snow from melting. Sealing leaks in the ceiling between the attic and the rest of the home can also prevent roof leaks caused by ice dams by eliminating the warm household air from the attic environment and helping to maintain consistent roof temperatures.

Treating Ice Dams

• Excess snow should be removed from the roof at the first sign of an ice dam. Commercial roof rakes may be used to remove snow, but you can also use a push broom. Professional roof snow removal services are available as well. If you've identified leaks or a large ice dam has formed, you can carve temporary channels into the dam through the use of warm water. The channels will allow excess water to run down through the dam, but these will serve only as a temporary damage control measure, as the channels will soon dam back up with additional ice, and the process must be repeated.