February 2, 2011

Ice dams can cause structural damage and make messes

By Tina Foreman
Farmer Staff Writer

In North Dakota, winter isn’t thought of as a rainy season, but for some area home and business owners, last week’s above average temperatures had it raining indoors. The problem of the indoor moisture caused by ice dams on the roofs.
Ice dams occur when escaping heat melts the snow on the roof and the water freezes when it reaches the cooler surface near the eaves. The best way to reduce the potential for ice dams is by providing adequate attic insulation and ventilation that keeps the roof cold, and to minimize any air leaks from the living space into the attic.
If you’ve had water dripping from your ceiling or running down your walls then you’re probably thinking about clean-up, not prevention.
“Driving around Watford City you can see a lot of houses with big ice dams on the roof,” says Lowell Cutshaw, Watford City city engineer/administrator. “So far we haven’t had a lot of problems with city structures. The Long X Visitor Center has had problems with ice dams the past couple of years. So this year we have had a company clean the snow off a couple of times and they also put heat tape in the gutters and on the eves. So far, it has worked to keep the ice from damming up.”
This is the time of year when ice dams will begin to develop on roofs and potentially cause damage. Homeowners have a few steps they can take to prevent ice dams.
An ice dam forms when snow melts and runs down the surface of the roof. As the melted snow hits cooler parts of the roof near the eaves, it refreezes. This process continues and eventually creates a dam of ice on the roof.
As more snow melts, the dam stops the water, which freezes, making the dam bigger, or backs up the melt water, allowing it to leak under the shingles into the attic spaces or eaves. This can lead to water stains in the ceiling, structural damage and mold growth inside the home.
Ice dams are clearly visible once they form, but to find out what causes them, a homeowner needs to look inside the attic.
Heat from inside the attic is the major cause of snowmelt on the roof forming ice dams. The greater the amount of heat in an attic, the greater the potential for snowmelt and ice dams.
The attic is warmed with heat leaking from a home’s living space. Anyplace where plumbing, heating or electrical components protrude into the attic and the openings are not sealed properly can allow heat leaks to occur. Recessed lights and attic access doors or ladders can be other areas where heat leaks into the attic.
Even if all the leaks into an attic from inside the home are sealed, heat from the home can be lost to the attic if it does not have proper insulation.
Another cause of snowmelt is improper ventilation of the attic space. Keeping all the heat out of the attic space is impossible, so allowing that heat to leave the attic through vents is important.
Depending on the construction of the home, this can be done through soffit vents, vents on the gable ends of the home or a ridge vent. Make sure the attic’s insulation does not block the air flow from the soffits or eaves. Use baffles to create a channel to hold insulation back from the soffit vents to allow air flow.
Removing snow from the lower portion of the roof so melting snow can run off is another way to prevent ice dams from forming.
Ice dams look like an ice ridge along the edge of the roof. They indicate that your house is leaking heat and does not have adequate attic ventilation. It’s important to look for these spots because water behind the ice may enter the house causing insulation to be ineffective, leading to the rotting of structural wood, staining wall coverings and creating conditions conducive for mold growth.
“Once the ice dams have formed and it gets warm, the melting starts underneath the snow and ice and with nowhere else to go, the water starts to enter the house,” adds Cutshaw. “If you have an ice dam, this is the time to take care of it because if we get a stretch of warmer weather again, it will be interesting and probably pretty difficult for those with ice dams.