Preventing Ice Dams

Ice Dame Prevention

What is an ice dam?

An ice dam is a ridge of ice that forms at the edge of a roof and prevents melting snow (water) from draining off the roof. The water that backs up behind the dam can leak into a home and cause damage to walls, ceilings, insulation, and other areas. A roof leak is often the first indication that you may have ice dams. Here are some tips on Preventing Ice Dams.

Image: extension.umn.edu

Ice dams form when there is snow on the roof and freezing temperatures.

Ice dams usually occur after a heavy snowfall and several days of freezing temperatures. Warm air inside your home leaks into the attic and will warm the underside of the roof causing snow and ice on the roof to melt.

The most likely causes of ice dams are due to heat loss, air leakage and the general warming of the house structure due to conduction from the heated building.

The melted water will drain along the roof, under the snow, until it reaches the cold overhang. The overhang tends to be at the same temperature [below 32 degrees] as the outdoors and the melted water will refreeze and form an ice dam and icicles. The ice dam can cause damage to the roof, which will result in water leaks to the inside.

The water back ups and finds cracks and openings in the roofing and then flows into the house. The result is water spots or dripping water on the ceiling under the roof damage.

Preventing Ice Dams

Immediate action:

1. Remove snow from the roof. This eliminates one of the ingredients necessary for the formation of an ice dam. A “roof rake” can be used to remove snow.

2. In an emergency situation where water is flowing into the house structure, making channels through the ice dam allows the water behind the dam to drain off the roof. Snow melt can also be used to facilitate these channels. DO NOT walk on any snow covered roofs!

Long-term action for preventing ice dams [I've had great success with these remedies. They are addressed in more detail in archived posts]

3. Increase the attic insulation to cut down on heat loss by conduction. State code requires an R-value of 38 above the ceiling for new homes. In narrow spaces, use insulation products with high R-value (6-7) per inch.

4. Seal air leaks into the attic. Warm air can flow from the house into the attic space – insulation alone will not stop air leaks.

5. Install heat cables on your roof and into your gutters.

6. Provide adequate ventilation to keep roof a more constant temperature.

Image: wxyx.com

7. Keep gutters clear of leaf debris.

Concord Carpenter

Who is Concord Carpenter?    ~ Robert Robillard is editor of A Concord Carpenter and principal of a carpentry and renovation business located in Concord, Massachusetts. Rob is a recognized leader in tool and how-to information for building professionals, he also hosts the Concord Carpenter Cable TV Show, offering the do-it-yourself audience in Boston's Meto West region expert advice on home repairs and maintenance. On his website, Rob covers all aspects of home improvement and remodeling, specializing in problem solving for home maintenance. Rob enjoys evaluating and reviewing tools and products and restoring vintage tools. The Concord Carpenter's motto: "Well done is better than well said!":

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