CADILLAC — The appearance of hanging icicles along roofs may appear harmless, but the thick ridges of solid ice can cause thousands of dollars in damage to a home.

Ice dams are created when snow melts high on the roof and refreezes near the bottom edge, known as the eave. The ice builds up from the edge, preventing melting snow from draining and damaging the home.

Mike McDougall, residential manager of Story Roofing Company, said ice dams are a reoccurring problem for homeowners each winter.

“I’ve seen ice dams 10 feet off the roof,” McDougall said. “Two years ago we had four or five guys working all winter long removing ice dams.”

Common areas for ice dams are the valley areas of dormers, the eave’s edge, around chimney and furnace flues and openings through the roof, such as pipes and vents.

Steve Kuhl, owner of The Ice Dam Company, said he’s witnessed the damaging results of ice dams first-hand as he’s torn through walls to repair insulation.

Failure to remove ice dams from roofs can lead to ruined insulation, water damage, soffit damage and gutter damage, he said. Once an ice dam is present, Kuhl warns homeowners that it only takes a little snow to bring about water damage inside the home. A general rule is the steeper the roof, the thicker the ice dam has to be to cause problems. On lower pitch roofs, a thin ice dam can pose potential problems.

Accumulating snow can also increase the risk of roof damage.

The Insurance Institute for Business and Home Safety defines the “danger zone” of snow roof risk as when snow and ice on a roof exceed 20 to 25 pounds per square inch.

Kuhl said a primary warning sign for an ice dam is ice or water on the exterior wall or through the soffit of the home. Other warning signs include ice forming behind the gutters or previous issues with ice dams during past winters.

“It’s very possible to have an ice dam even if the ice doesn’t manifest into large icicles hanging off the roof or gutters,” Kuhl said. “It’s not simply a matter of looking up at the eaves.”

Ice dams can also manifest above skylights and in roof pan areas.

Variables affecting the likelihood of ice dams forming include the architecture of the home, the amount of snow, daily temperature fluctuations and the quality of insulation and ventilation in the home, Kuhl said.

“Ice dams at their most fundamental state are the result of heat escaping the home and entering the attic,” Kuhl said. “The heat warms an area of roof, warming the snow, and the melted water travels down to an unheated area of roof such as the eaves before it refreezes.”

Preventing damage from ice dams can be accomplished by installing roof heating cables or repairing improper insulation and ventilation in the home, he said.

McDougall said installing a roof-mounted power vent can provide the necessary home ventilation to prevent ice dams in the winter.

“Insulation and ventilation are the key to preventing ice dams from building on your roof,” McDougall said.

De-icing cables melt passageways for water to flow off the roof and prevent dams. The cables are installed along the roof edge where ice tends to build up.

Kuhl and McDougall said roof rakes are also a preventative measure to minimize the likelihood of ice dams.

But not all methods can be helpful.

Kuhl said using hammers, axes, pressure washers or de-icing salt to remove ice dams can potentially damage your roof.

“Using de-icing salt can not only void your roofing warranty, it also has a corrosive effect on materials such as aluminum gutters and various adhesives,” Kuhl said.

McDougall advises homeowners that roof maintenance is the best means of preventing ice dams from becoming a problem this upcoming winter.

“The best thing homeowners can do is keep the snow from accumulating on their roof,” McDougall said.

More information on preventing ice dams and heat cables can be found at www.icedamcompany.com.