Learn About Ice Dams and Icicles

learn how icicles and how to prevent ice dams

Learn About Ice Dams and Icicles

Are your energy dollars literally dripping off the roof?

Big icicles and ice dams are typically caused by poor or missing insulation and air leakage from your house into your attic. In the winter, this warms the roof and causes the snow to melt faster that it normally would. The melting snow then moves down the roof slope until it reaches the cold overhang, where it refreezes.

The process forms icicles and can actually create a dam that eventually forces the water to back up under the shingles and sometimes into the ceiling or wall inside the home. In addition to roof and water damage, ice dams can cause structural decay and rot or cause and mold and mildew to form in attics and on wall surfaces. The icicles themselves can do damage to your home—or seriously injure people—when they fall.

Roof ice, icicles, and ice dams can result in:

  • Structural or property damage—and serious injury—from falling ice.
  • A leaking roof (height of leak depends on extent of ice dam).
  • Wet, ineffective insulation.
  • Stained or cracked plaster or drywall.
  • Rotting timber.
  • Stained, blistered or peeling paint.

Big icicles themselves, like those shown here, are obvious signs that you’re at risk. But snow melt patterns can also indicate a problem of too much heat loss.

icicles provide a warning that an ice dam may follow

How to Prevent Ice Dams

Fortunately, you can dramatically reduce damage from ice damming by sealing the holes connecting your heated living space and the attic, as well as properly insulating your attic. There are different techniques to stop air leaking through recessed lights, leaky heating ducts, attic access doors, and plumbing and electrical penetrations. Sealing these leaks keeps warm air in your house were it belongs. Together, with adequate levels of insulation, this greatly reduces the chance of ice damming and large icicles. You do NOT just want to add more insulation before sealing the air leaks—this can actually create additional problems that can also damage your roof.

You cannot eliminate icicles completely. Small icicles are normal. And some roof architecture–especially big valleys draining to a small corner– are especially challenging. But if you have long icicles or thick heavy ice you should act quickly to prevent damage. (And this means preventing the ice from forming in the first place, not risk life, limb, and your roof trying to chip off ice that’s there.)

Do it right. Find the important leakage points and seal them up. Then add a lot of insulation. And afterwards, as with any time you change the way your house works, have your combustion appliances tested to make sure they’re operating safely and efficiently.

An added benefit to this, of course, is you’ll save energy, save money, and be more comfortable in your home, too!

How NOT to Prevent Ice Dams

Do not climb up on your roof and hack or chip away at ice. This is very dangerous. And there’s substantial risk of roof damage. While you can rake snow off the roof—it’s only potentially effective if you decide that you have an ice-damming problem the day of a big snowstorm. You can do it yourself by buying a snow rake, or hire someone to do it for you each time you get a snowfall. But do you really want to add shoveling the roof to your existing shoveling chores, or add to your current snow removal bills? And just shoveling the snow off the first two or three feet of the roof isn’t going to do it: the show further up the roof can melt down and create dams.

Ditto with heat tape, which not only costs as much as $600 to buy, but must then be installed and can be very expensive to run. (Set an electric heater outside and then tell me about your electric bill!) Electric heat tape requires fasteners, which penetrate the shingles to hold it in place, and can damage shingles. And unfortunately, many people let heat tape run even when not needed – when there is no snow on the roof, for example – causing even higher bills.

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