Preventing Ice Dams to Preserve Indoor Air Quality

Note: This information was posted originally in the year 2000.

Over the past several winters we have been testing an anti-ice damming insulation system. Ice damming is an indoor air quality problem in colder climates. Ice dams occur when heat escaping from the house melts the snow on the eave line into solid ice. When the weather warms water leaks under the eaves providing moisture to encourage the growth of fungus which thrives in moist, dark, wet places. The spores given off contain several toxins, the most significant of which are mycotoxins which are very irritating to the upper respiratory tract. Mycotoxins may cause headaches, nose bleeds, and immune system suppression. Some fungus, such as, Alternaria are known allergens. 
While air cleaning devices such as the Clairity (no longer manufactured) are effective in removing mold and fungus spores from the air, it is best to prevent the problem from occurring. Usually keeping the wood of the roofing system dry will cure the problem. Also, replacement of materials usually is more effective than the application of fungicides.
The immediate cure is to remove the snow, that is the moisture supply from the roof. In North-east Ohio where I live the problem usually occurs on the flat or shed roofs of family rooms attached to the house. In the case of flat roofs easy access is available thru the second story by door or window to shovel off the roof. I recommend a plastic shovel or push broom. For the shed roof a “roof rake” is available in most hardware stores. this consists of a rake like shovel with about four extension pieces. With the roof rake you can clear the snow off the shed roof without leaving the ground. Either procedure should not damage intact roofing materials. And while “roof raking” may go down in history as the stupid chore of the new millennium, it is infinitely preferable to tripping over several dozen drip catching buckets.
The long term cure lies in improved insulation and gutters. Gutter heaters are of no immediate help. Several gutter manufactures offer gutter covers, such as, the Gutter Helmet™. These covers direct water into the gutter while allowing leaves and snow to fall off. The insulation system I installed in my study ceiling consists of standard R-19 fiberglass insulation backed with Reflectix™ radiant heat barrier (aluminum coated bubble wrap). This system keeps the heat inside to preventing the snow on the roof from melting. Also in the summer when the rest of the house is air conditioned , the study is about five degrees cooler.

Steven R. Pressman

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