Winter Woes - Ice Dams
Icicles hanging along the eaves of your home may look cozy, but they can actually spell trouble. That's because the same conditions that cause those icicles to form—snow-covered roofs and freezing weather—also lead to ice dams: thick ridges of solid ice that build up along your eaves or in your gutters.
Birth of an Ice Dam
When snow collects on your roof, it will eventually begin to melt, even if the temperatures stay below freezing, because of the heat of rising from your home, through the roof. The run off then stops at your eaves, or your gutters, which are colder in temperature than your roof, causing the melted snow to refreeze. This creates an ice dam which prevents the drainage of any fresh snow that melts. When an ice dam is formed, moisture is unavoidable. As the ice begins to melt, the water must go somewhere, and penetrates beneath the shingles, and eventually the plywood, causing damage to your roof. Dams can also pull down gutters, damage shingles, and cause the melting water to back up and pour into your home. When that happens, the results can range from peeling paint, warped floors, and stained or sagging ceilings to soggy insulation in the attic, which loses its R-value and can become a magnet for mold and mildew.
Photo credit: Travelers Insurance
Here are some stop-gap measures to address the problem in the short term:
- You can try hacking away small chunks of the ice dam with a blunt mallet. Using a hammer, chisel, or shovel is bad for your roofing—and could be dangerous for you.
- Blow in cold air: set up a box fan into the attic and aim it at the underside of the roof where water is actively leaking in. This targeted dose of cold air will stop the leak in its tracks.
- Rake it: Pull off snow with a long-handled aluminum roof rake while you stand safely on the ground. A rake with wheels won't harm the roofing. If your roof is too tall to reach via the rake, use a licensed roofing contractor who is adept at ladders and knows safety procedures for this type of home maintenance. It's best to not try this yourself.
- Melt troughs through the ice dam with calcium chloride ice melter. Do NOT use rock salt! It will damage paint, metals, and plants beneath the eave and where the salty water drains.
A good trough-maker is a tube of cloth (a leg from an old pair of panty hose works well). Fill it with calcium chloride, tie off the top, and lay it vertically across the ice dam. It will slowly melt its way down through the dam, clearing a path for the underlying water to flow free.
Preventing Ice Dams
The best way to keep snow from melting on your roof is to make sure that your roof is properly insulated. Proper insulation will ensure that no warm air is escaping to prematurely melt snow and overload your eaves or gutter system. You'll also want to seal off every possible air leak that might warm the underside of the roof.
Many area homeowners use sheet-metal ice belts. This eaves flashing system tries to do what metal roofing does: shed snow & ice before it causes a problem. Sometimes, though, a secondary ice dam develops on the roof just above the top edge of the metal strip.
Gutters can be damaged from snow and ice that builds up after a heavy snow fall. Keeping your gutters clean prior to the winter months is one way to help prevent ice dams and the resulting buildup. Gutters that are clogged with leaves and other debris will speed up the process of ice damming and the resulting overflow. Many area residents use heat tape in their gutters and along the eaves of their roofs to keep ice from forming. If opting for this route, try a thermostatic heat tape to prevent the high electric bills that can result.
It may seem counter-intuitive, but the best time to run heat tape is during the day. Heat tape is not effective enough to sufficiently melt ice during cold evenings, and it will just waste power all night long. When the sun is out and snow starts melting, the dripping water needs a path to drain off the roof. Heat tape can melt a channel in the underside of the snowpack on your roof and give water a route to drain out. And heat tape installed in gutters and downspouts allows water to drain away from the roof, rather than getting plugged up by a dam of ice.
Whatever you do, consult a professional An area roofing contractor is your best bet when combatting winter woes, and can make suggestions for your home's particular situation.