for Cold Climate Housing and much more

Last Updated: , Created: Sunday, January 14th, 2001

Eleminating ice dams

Nancy in Manitoba has bad ice dams on her roof. She sent me a great sketch of her whole attic arrangement, complete with knee walls and cathedral ceilings, not to mention a dormer -- and there is no ventilation in the roof in front of the dormer.

The guidelines for eliminating ice dams are simple, but difficult to execute in real houses. The objective is to prevent the heat from inside the house from melting the bottom of the snow pack, where it can drip down to the edge of the roof and re-freeze. Block off all air leaks to the attic area -- they not only draw moisture into the attic, but a lot of heat. Insulate the floor of the attic as completely as possible to further minimize the heat that gets into the area under the roof. Then ventilate as completely and thoroughly as possible, washing the entire underside of the roof with cold air to remove the little bit of heat that you could not stop.

For several detailed discussions of these problems, check the keyword list for "Ice Dams".


Keywords: Ice Dams, Ice, Roof

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