Keep ice dams at bay

If you live in a cold climate, chances are good that at some point your home may be affected by an ice dam. Ice dams can do quite a bit of damage, but if you're aware of the situation, you can take some proactive steps to minimize or even prevent ice dams from forming.

Why ice dams occur

During the winter, snow builds up on the roof. If the winter temperatures are cold enough, the sun's heat is insufficient to melt off much of the snow layer, so it remains in place, and even continues to grow.

In the meantime, you're using the furnace or the fireplace to keep the house warm, and some of that heat is lost into the attic. With the snow on the roof acting as an insulator, the heat from the attic begins to work on the underside of the snow layer. Soon, a thin film of melted snow -- liquid water -- appears on the underside of the snow layer, between the top of the roofing and the underside of the snow. This water runs down the top of the roof, beneath the snow, until it reaches the eaves.

Once at the eaves, the water is past the end of the attic. Now there is no more heat being lost from the house to keep the water warm enough to remain a liquid. The water freezes, forming a dam. The cycle repeats itself, the dam grows, and the water backs up farther and farther. Once it backs up to the heated part of the attic again, it no longer freezes. Remaining as liquid water instead of ice, it works under the shingles and gets into the house.

Warning signs

The first sign of potential trouble is a layer of ice forming along the eaves of the house, right at the very edge of the roof. You may also see that ice has been accumulating inside the gutters and has finally grown high enough to be visible from the ground. At this point, you can carefully try to remove the snow layer from the eaves of the roof. The idea is to remove the insulating ability of the snow, so that when temperatures come up a little, the ice will melt. But DO NOT give in to the temptation to use a pick, sledgehammers, ax, blow torch, or other drastic measures!

Icicles are the next warning sign. They're actually part of the ice dam, occurring as some of the dam melts, flows over the edge of the roof, and refreezes. As with the ice dam, as the cycle repeats itself, the icicles simply keep getting larger. Icicles warn you that the dam is getting worse. If the ice is sufficient to be dripping over the edge of the roof, it's also moving farther up the roof. You might still be able to have a small amount of impact on the problem if you remove the snow at the eaves, but again, how much good it does seems to be totally weather-dependent. ...CONTINUED

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