“Removing ice from roofs with shovels, chippers, axes, chemicals or heat can damage shingles, gutters and other building components, and can be very dangerous,” said Commerce Commissioner Mike Rothman. “To prevent ice dams in the future, the best course of action is to attack the root cause of ice dams, which is attic air leaks. Sealing those air leaks will prevent ice dams and save on your energy bill.”
Cause of ice dams Roof ice dams cause damaged shingles, sodden insulation, and ruined walls and ceilings. Although sometimes thought of as a problem with roofing or attic ventilation, ice dams are actually caused by the presence of warm, moist air in the attic, combined with snow on the roof and the right weather conditions. An abundance of snow contributes to ice dam problems.
Ice dams occur when heat leaks into the attic and melts the underside of the snow on the roof. The melted snow then flows down the roof surface until it reaches a cold spot (such as the eaves or soffit), where it forms a frozen dam, behind which more snowmelt and ice pile up. The ice buildup can back up under the shingles, damaging them and allowing water to leak to the ceilings and walls below.
The solution To avoid these types of problems and eliminate most ice dams, attic air leaks around wires, plumbing vents, light fixtures, and chimneys must be sealed with caulking or expanding spray foam, and attic insulation should be installed to a minimum R-50 as space allows.
A first step in solving ice dams—and to making your home more energy efficient—is to have an advanced energy audit. The audit will use equipment such as infrared cameras to identify air leaks and will offer action steps to prevent ice dams. Advanced energy audits can be facilitated by your gas or electric utility and members of the Minnesota Building Performance Association (www.mbpa.us). Once the problem areas are diagnosed, get bids from several licensed contractors and have the work done.
What NOT to do in addressing ice dams: · Installing heating cables will shorten the life of your roof and cost you money to operate. · Removing ice with shovels, chippers, chemicals, or heat can damage shingles, gutters, and other building components—and can be very dangerous. · Adding roof vents—including powered vents—will not eliminate ice dams, and often makes the problem worse. · Inadequate insulation, especially near the eaves, is a contributing cause of ice dams. Adding insulation, especially on the top plate of exterior walls, can reduce heat transfer to the roof deck, but insulation alone is insufficient to stop air leaks or prevent ice dams.
The Commerce Department’s Division of Energy Resources (DER) offers a fact sheet on ice dams called “Solving Ice Dams.” For more information on ice dams and ways to conserve energy in your home, check out the DER energy guide “Home Envelope” or visit www.energy.mn.gov.