What causes ice dams?

If you live in New England chances are you know what an ice dam is. In case you don’t, an ice dam is a wall of ice that forms on the edge of your roof where the gutters and edges meet. But do you know what causes them?

Ice dams are most often formed by poor attic insulation and poor attic and roof ventilation, resulting in a significant amount of heat loss through the attic and roof. The buildup of heat causes snow to melt at a faster rate, and as fresh snow continues to accumulate, the melted snow can become trapped under the new, heavier snow. This buildup of water has nowhere to go and ultimately seeps into your home. The formation of ice dams can occur even if you have a strong and well-maintained roof.

Your best prevention tool against ice dams is to seal any warm air that might be escaping to your roof. This might mean sealing air ducts, adding more insulation to your attic,or making sure your attic is sufficiently ventilated so that warm air will not become trapped.

This week’s forcast might be cold, but at least there is no snow. I think we all need a break.

Steve Murphy

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