The key to preventing ice dams is simply to keep your attic and roof cold. While frozen, they’re no more trouble than the icicles that hang down. But during the warmer parts of a winter day, water melting off the roof pools behind the ice then seeps back up under the shingles.
To keep your roof cold, follow these steps:
1. Close up attic bypasses. In the average home, about 1/3 of heat loss is through the ceiling into the attic, mostly from air leaks caused by unblocked walls, gaps in drywall, and cracks around light fixtures, pipes, and chimneys. A professional will pull back insulation and plug the leaks using foam, caulk and other methods.
2. Measure your attic insulation level. Check the depth of your attic insulation. Building codes require about 12-14”. Add more if you have less than 8”. Blown-in cellulose and fiberglass are best because they fill more tightly leaving fewer gaps. It’s usually worth hiring a professional for this job.
By stopping air leakage to mitigate ice dams, you’ll save energy and reduce both your heating and your air conditioning bills.