How to Prevent Ice Dams


By: Douglas Trattner

During the colder months, preventing ice dams should be a primary concern. Here’s how to protect your home from damage.

The Damage Ice Dams Can Do


Ice dams are responsible for cracked plaster ceilings and walls, peeling paint, soaked carpets, and buckled wood floors. Less visible but no less destructive effects include drenched insulation, rotting joists, and the formation of mold. The most common form of ice dam damage is collapsed rain gutters, which can cost $100-$300 per side to repair.

What Causes Ice Dams

As heat rises from a home, it melts the accumulated snow on the roof. That melted snow travels down the roof in liquid form until it reaches the eave line and gutter, where it refreezes due to colder temps. This ice ridge continues to expand, blocking the flow of subsequent snow melt.

As water continues to melt higher up the roof, it collects behind the ice dam in the form of a puddle. Because that water sits over the warmer portion of the roof, it doesn’t freeze.

In order for ice dams to form, there needs to be roof snow buildup, home heat loss, and subfreezing temperatures. The more snow, the larger the heat loss, and the longer the subfreezing temperatures remain, the higher the likelihood that ice dams will materialize.

How to Prevent Ice Dams


Typical steps include insulating the attic floor and installing soffit, gable and/or ridge vents to expel heat. Folding attic stairways and recessed light fixtures also need to be insulated. “All penetrations into the attic from the heated living space need to be addressed,” adds Bruell. Homeowners can expect to pay $800-$1,500 to insulate the attic, plus another $300-$600 for the installation of vents.


Tip: You’ll save money with insulation. According to the U.S. Department of Energy, adding insulation to an unheated attic will have a greater impact on energy consumption than placing it anywhere else in the house. A properly insulated and ventilated attic not only reduces winter heating bills, it will trim summer cooling bills by expelling heat buildup. Proper attic insulation can save you 10%-50% on your heating and cooling bills.

Deicing Alternatives


Electrically-heated deicing cables, which install along eave lines to inhibit water freeze, are only moderately effective, says Bruell. “These heat cables often just back up the problem, forcing the dams to form higher up the roof.” In addition to the purchase price ($150-$300), and installation ($300-$500), these cables require electricity to run. They also can shorten the life of roof shingles.

How to Remove Ice Dams




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