To Stop Ice Dams You Need a Cold Roof - Boston, Worcester

There has been a lot of snow around Boston and Worcester. Your home may look beautiful with all the icicles hanging off the roof, but in actuality, looks can be deceiving. Icicles are a sign of a much larger problem, which can become costly: Ice dams.

Ice dams and icicles form when snow melts, runs down your roof and refreezes near the edge. This only occurs when part of your roof warms to above 32 degrees F, warm enough to melt the snow, while the roof edge remains below freezing. This scenario is often the result of a warm attic. In most homes, heat escapes through ceilings into the attic and warms the wood and shingles directly above it. Although the outdoor temperature is below freezing, the snow melts over the warmed section of roof. When the water from melted snow and ice runs down the roof, it hits the cold edge not warmed by the attic. There it freezes, creating a rim of ice. This rim can grow, trap more water behind it, and bingo—you have a full-fledged ice dam.

The key to preventing ice dams is simply to keep your attic and roof cold. After a snowfall, a cold roof will have a thick blanket of snow. A warmer roof, however, will soon have clear spots where the snow has melted off, and may well have icicles hanging from the eaves.

To keep your roof cold, follow these three steps:

1. Close up attic bypasses

In the average home, about one-third of the heat loss is through the ceiling into the attic. And most of that loss comes from air leaks caused by unblocked walls, gaps in drywall, and cracks around light fixtures, plumbing pipes, chimneys, access hatches and other ceiling penetrations. Air leaks can be tough to stop. You have to climb into your attic, pull or rake back insulation, and plug the leaks using foam, caulk and other methods. Low roof angles make some air leaks difficult to reach.

Bonus: By stopping air leakage to mitigate ice dams, you'll save energy and reduce both your heating and your air conditioning bills.

2. Measure your attic insulation level

You should have the depth of your attic insulation checked and measured. Building codes require about 12 to 14 in. of fiberglass or cellulose. Have more insulation added if you have less than 8 inches and if you have had ice dam problems in the past. Blown-in cellulose and fiberglass are usually better than hand-placed batts, because they fill more tightly around rafters, joists and other obstructions, leaving fewer gaps. It's usually worth hiring a professional for this job; you won't save much by doing it yourself.

3. Add roof and soffit vents

Attic ventilation draws in cold outdoor air and flushes out warmer attic air, cooling the attic and the roof in the process.

In addition:

Insulation, especially blown-in insulation, can block the airflow. Insulation specialists should make sure the spaces between rafters over the exterior walls are open. Baffles usually prevent this problem. If you don't have them, have them added before installing additional insulation. A shot of air from a compressor hose from the outside will open plugged soffit vents.

For more information on adding insulation to prevent ice dams, contact Custom Insulation.

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