Roofline with ice dams

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How to Prevent Ice Dams as Snow Melts, Refreezes

March 5, 2021

As more of the country breathes a sigh of relief as temperatures rise and the countdown to spring shortens, there’s a weather-related concern that remains. Melting snow followed by a cold snap—which is on the way for many parts of the country in the coming week—may cause ice dams to develop and bring a cascade of water into homes. Even if your house hasn’t faced this problem this year or in prior years, it’s still wise to think ahead to avoid the potential mess and repair costs, which can be significant.

Design, building, and remodeling experts at Orren Pickell Building Group in the Chicago area report that the company has been contacted by a number of homeowners who faced the challenge this year due to heavy snowfall and unusually cold temperatures followed by warm days.

How Ice Dams Form

“When we experience a polar vortex, where there’s a combination of heavy snow and then a dramatic decrease in temperature, it’s a situation that can create the perfect ice dam situation,” says Eric Pickell, head of sales and marketing. “That happened this year because of the amount of snow from several large storms and sustained cold, followed by a warming cycle.”

Ice dams build up this way. As heat rises from the house into an attic, it melts the snow on the roof, which drips into the cold gutters and, when cold enough, forms a block of ice—the ice dam. “As the dam enlarges, it may trap water behind it that gets pushed back under the shingles and into the attic as it melts, or into the house if there’s no attic,” Pickell says. Having a lower-pitched roof and poor insulation may exacerbate the problem.

What You Can Do

There are several steps homeowners can take to avoid ice dams. Advise them to consider these possibilities:

  • Visually inspect the exterior of the house. Make sure ice and snow aren’t accumulating at the gutter line. If they do, the homeowner should hire a professional to clear the roof rather than try to tackle the problem on their own. “There are professionals who are licensed who know how to steam icicles and ice dams away,” Pickell says. These pros also may use roof rakes and shovels. However, Pickell notes that because of the accumulation this winter, many professionals were more difficult to hire.
  • Be sure a gutter and downspout system is in tip-top shape. Gutters may contribute to the problem when snow and ice build up and cause water to back up. This is why a gutter inspection is key. On the other hand, gutters are important for the rest of the home’s good maintenance because they direct water from the roof, down through downspouts, and away from a house rather than remain at its base by the foundation.
  • Take care of the roof and gutter system by having it regularly inspected. This also includes sealing all points where water can infiltrate an attic or conditioned spaces of the home through roof sheathing. More insulation may be needed in the attic if there are areas where the insulation has been removed or where it has settled. Additionally, if the home’s HVAC system and ductwork are located in the attic, these need to be properly sealed and insulated so warm air isn’t leaked into the space, which can prematurely warm the roof and create the right condition for an ice dam.
  • Make any needed repairs promptly. Gutters and downspouts may need repairs and replacement, depending on the material used and how they were constructed. Generally, Pickell recommends five- or six-inch-width gutters and properly sized downspouts. These may be aluminum, galvanized, or copper. Aluminum is generally the most cost-effective, though copper and galvanized can last longer with proper maintenance. Where gutters and downspouts often fail is near their seams, which may wear out. These should be inspected and sealed regularly.

Homeowners may also consider adding de-icing cables along the length of eaves, in any valleys, and along downspouts in areas where ice dams have formed to prevent future problems. The downside of the cables, Pickell says, is that they can detract from a home’s aesthetics and require a power source. The cost can be about $1,000 to $2,500, depending on the size of the roof.