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Ice Dams 300

The water that backs up behind an ice dam can leak into a home and cause damage to walls, ceilings, insulation and other areas.

Simple steps can prevent ice dams, U of M expert says

December 17, 2010

Last week’s snow dump reintroduced Minnesotans to ice dams, a common winter pest. Usually not noticed until it’s too late, ice dams are a ridge of ice that forms at the edge of a roof and prevents melting snow water from draining off the roof. The water that backs up behind the dam can leak into a home and cause damage to walls, ceilings, insulation and other areas.

A University of Minnesota expert who can comment on ice dam formation and prevention is:

Patrick Huelman, associate Extension professor, Department of Bioproducts and Biosystems Engineering

Huelman says it takes three things to have an ice dam: (1) snow cover on the roof, (2) outdoor temperatures at several degrees below freezing and (3) a melting roof above a freezing roof. “The freezing roof is generally at the overhang where it is approximately at outdoor conditions, while the melting roof is usually heated by heat loss from the house,” Huelman says.

Heat loss from the house happens in two ways: (1) transmission losses through the insulation and (2) air flow through bypasses and holes between the house and the attic space. This air flow is driven by natural and occasionally mechanical pressures in the home. Huelman says if one stops the heat loss this will slow or prevent the melting, removing the water to create the ice dam. In addition, this saves energy and money.

Huelman says there are some intervention measures that can reduce the temperature in the attic. The primary one is attic ventilation. “This can help marginal ice dam formation, but won’t completely eliminate the melting condition for homes with more severe heat loss. Snow removal should be a last resort. It is dangerous, hard on the roofing materials and can be expensive.”

For a primer on ice dams, including prevention tips, visit http://www.extension.umn.edu/distribution/housingandclothing/dk1068.html.

To interview Huelman, contact Jeff Falk, University News Service, (612) 626-1720 or jfalk@umn.edu; or Catherine Dehdashti, U of M Extension, ced@umn.edu, (612) 625-0237.

Expert Alert is a service provided by the University News Service. Delivered regularly, Expert Alert is designed to connect university experts to today’s breaking news and current events. For an archive and other useful media services, visit www.unews.umn.edu. Views expressed by experts do not represent the views of the University of Minnesota.

Tags: College of Food, Agricultural and Natural Resource Sciences, Extension

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