Icicles are a sign of ice dams on roof

This article submitted by Linda Stelling on 3/7/01.

Snow on a driveway or sidewalk is hard to miss, and homeowners have been clearing a lot of it this winter. But homeowners should also take a look at another place that snow accumulatesÉ their roof.

Jerry Mehr, M&M Lumber, said icicles hanging from roof eaves are an indication that there are ice dams on the roof. "This is a winter where everything that can go wrong with a roof will," Mehr said.

When snow and ice from the peak of the roof melts, water slowly runs down the roof. When the water hits a cold spot on the roof, the water refreezes. As more melting water hits the cold spot, it begins to build up, becoming an ice dam, and eventually works its way underneath the shingles.

"The best thing to do is clean the roof as best as you can, especially near the overhang to prevent ice from backing up and having water leak into homes," Mehr said.

Water leaking into homes can damage interior and exterior walls, insulation, and ceiling finishes.

Another item to check on the roof are the vents and louvers. If the vents or louvers are covered with snow, the attic cannot breathe and frost will build up in the attic. This can lead to condensation problems.

"When shoveling off snow, be careful not to damage the shingles or vents as that will create a bigger problem," Mehr said. He advises not to take all the snow off the shingles. Let the sun melt the layer closest to the shingles, eliminating the chance of damaging the shingles with your shovel.

"This winter is a good test for roofs," Mehr said. Typically, a roof is designed to hold 10 pounds per square foot, depending on the type of snow, he said. It's uncertain how much weight some buildings will take before they collapse.

Several years ago, several buildings in the area collapsed from the weight of snow on the roof.

Snow removal tips Pat Kearney, Kandiyohi County extension educator suggests homeowners take the following steps:
•Remove snow from the roof. A roof rake and a push broom can be used to remove snow.
•In an emergency situation to stop water from continuing to flow into the house, make channels through the ice dam. Hosing with warm water will do this job. Work from the lower edge of the dam up. The channel becomes ineffective within days, however, and is only a temporary solution.

According to author Duane Johnson, the Family Handyman, the way to prevent ice dams is to keep your attic and roof cold. After a snowfall, a cold roof will have a thick blanket of snow. A warmer roof 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, Johnson offers the following tips:
• 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.
•Measure your attic insulation level. Check the depth of your insulation. Building codes require about 12 to 14 inches of fiberglass or cellulose. Add more if you have less than eight inches and have had ice dam problems.
• 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. The greater the vertical distance between the outlet and inlet of air flow the more effective the system.

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