
Minnesnowta has an epidemic of ice dams. Ice dams form on the roof of a building as the snow melts and then runs down to a colder overhang. The ice builds up in the gutters and then as the melt flows to the dam, it pools and freezes behind, and so on and so on. My dams are about a foot high in places, and there are icicles that could pierce your chest.
Principle among causes are a poorly insulated attic. My house is a common "story and a half" that doesn't have much insulation at all. I postponed replacing insulation because I thought it might take a while to recoup my expenses in energy bills. Now I realize that it must be done to save the roof and the interior walls. I had water dripping in behind a front window.
So, damn ice dams...
What: dam of ice along the edge of roof, usually beginning in a gutter
Remedy:
- You can have them steamed off for about $300-800.
- Many people this year are trying out "salt bombs" - eco-friendly (non-corrosive) salt melt in nylon stockings laid over the dam to melt a channel for future run off.
- Remove loose snow.
Prevention:
- Properly insulate the attic and allow ample air flow.
- Rake the snow from the roof after a snowfall.
- Install heat coils along roof edge.
- Live in a warm climate.
Resources:
http://blog.lib.umn.edu/umnext/news/2010/12/snow-ice-cause-concerns-about-farm-buildings.php
http://www.ehow.com/how_4914834_fix-roof-ice-dam.html