As snow piles up, how to guard against ice dams and damage to roofs

A forecast of two rounds of snow this week brings the threat of another wintry mess: ice dams.

Some areas, especially southeast of I-55, could see more than eight inches of snow through Thursday, according to the National Weather Service.

All that snow piling up on roofs should give homeowners a reason to shudder this time of year.

Ice dams develop as snow begins to melt with the escaping heat of the house's attic, runs down the roof and refreezes at the non-heated edges, jamming up gutters. With nowhere to go, the water could back up and leak into homes.

The weather service and roofers recommend using a roof rake to help guard against the buildup of ice dams in freeze-thaw cycles.

Homeowners can extend a rake to clear snow up the slope of the roof from the gutters, but they should use caution, roofing companies say.

Do not start chopping at the ice dam with a shovel, a hammer or an ax. You'll end up doing more harm than good to the roof itself.

And be careful not to scrape away roofing materials. You don't have to get right down to the shingles.

If you're not in a position to use a rake, call professionals. It should also go without saying: Don't climb onto the roof to remove snow. Roof rakes, available at home improvement stores, can reach some 20 feet while you stay safely on the ground.

Homeowners also can try placing nylon stockings filled with calcium chloride perpendicular to the gutter to cut channels in the ice - just like making a hole in a dam - so at least the water can run down and over it.

But there's usually an underlying culprit. Improper insulation in your attic, the weather service says, can cause heat loss from the interior of the home and ice dam issues.