Ever heard of an ice dam? If you've experienced the home damage that can be caused by these wintertime hazards, you won't soon forget the term!
An ice dam is a hump of ice that forms at the edges of a roof, caused by snow and ice. Ice dams may be caused when the attic gets warm enough to melt the underside of a layer of snow on the roof. What happens next is water drips down the roof until it reaches the colder eaves, where it refreezes. Gradually, all that water grows into a mound of ice. Dams can also be caused by gutters that trap snow and ice, which can build up high enough to provide the foundation for an ice dam.
Icicles hanging from the edge of the roof are a good indication that an ice dam may be forming. Ice dams are more commonly found in older homes that lack proper insulation and ventilation.
Once they've formed, ice dams can cause plenty of property damage. As an ice dam grows bigger, melted water can back up behind it and seep underneath shingles, penetrating the roof. That water can drip down into the home, causing peeling paint, warped floors and sagging ceilings. If the ice jam becomes heavy enough it can fall, tearing down gutters and shingles along with it.
The best way to prevent ice dams from forming is preventing the roof from warming in the first place. To do so, add extra insulation in the attic and seal off any air leaks from the main living space. Cover unsealed attic hatches or whole-house fans with weather-stripped caps, and seal and insulate HVAC and exhaust ducts. Gutters should be cleaned in the fall so water, rain and melted snow can flow off properly. And after snowfalls of 6 inches or more, use a roof rake or shovel to remove snow that has accumulated on top of your home.
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