ice damsThe last time you saw long, sparkling icicles hanging from your roof, you may have thought nothing of it. However, the formation of icicles is a sign that you have an ice dam on the roof. Learn about ice dams and why you need to prevent them.

What Are Ice Dams?

Homes in Illinois are subject to the pervasive and damaging winter roof problem known as ice dams. An ice dam is a wall of ice that builds up along the eaves. You can’t always see the dam because it forms beneath a layer of snow, but icicles are a clue that you need to take action to stop the ice dam from damaging your roof.

Causes of Ice Dams

Ice dams form when warm attic air raises the roof’s temperature to above freezing. This melts the underside of the snow pack, and the resulting water runs toward the eaves. There, the roof temperature is cooler and the water refreezes into ice. The underside of the snow pack continues to melt and water continues to flow down the roof until it reaches the ice dam where it backs up and remains stuck on the roof.

Ice dams form or get worse after a heavy snowstorm because snow is a very effective insulator. It traps heat rising through the roof from the attic and melts the snow to create bigger, more destructive ice dams.

Why Do You Need to Prevent Ice Dams?

Roof shingles aren’t designed to block water flowing from the eaves upward, which is what happens when ice dams form. This causes water to flow under the shingles, resulting in a number of problems, including:

  • Loosening and damaging shingles
  • Causing water to back up and pour into the attic
  • Destroying attic insulation
  • Warping and peeling paint off the walls
  • Causing the ceiling to stain and sag
  • Leading to mold and mildew growth, which degrades indoor air quality

How Can You Prevent Ice Dams?

The only way the underside of the snow pack melts first is if the roof is above 32 degrees and the outside temperature is below freezing. When the temperature is above freezing outside, the snow simply melts and runs off the roof. Therefore, the trick to prevent ice dams is to keep the underside of your roof cool. Here’s how:

  • Eliminate sources of heat in the attic: If the furnace or water heater is located in the attic, look into relocating it. Also, if you have any ductwork traveling through the attic, seal and insulate it to prevent transferring heat to the space. Finally, make sure the dryer vent and kitchen and bathroom exhaust vents are sending air to the exterior, not into the attic.
  • Improve attic insulation: The air leaking up from your home is another source of heat you must combat. Make sure all attic floor penetrations, recessed light fixtures and the attic hatch are adequately sealed and insulated. You also need several inches of insulation over the entire floor to achieve the recommended heat resistance value, or R-value, of R-38 to R-60 for homes in Illinois.
  • Install ventilation: It may seem counterintuitive to keep the attic as cold as possible in the winter, but a cool attic is the key to preventing ice dams. Make sure the attic is fitted with continuous soffit and ridge vents, as well as baffles to provide an air ventilation channel along the underside of the roof. This system allows cold air to circulate under the eaves and travel along the baffles until it circulates back outside through the ridge vents at the top of the roof, effectively keeping the roof the same temperature as the exterior.

Getting Rid of Ice Dams

Despite your best efforts, ice dams may still form. Hacking at the ice with a shovel is bad for shingles and dangerous for you. Throwing salt on the roof is no good either, so short of praying for good weather, use these tips to stop ice dams in their tracks:

  • Send a blast of cold air: Set up a box fan in the attic and aim it where water is leaking inside. You’ll stop the leak in minutes.
  • Use a roof rake: While standing safely on the ground, use a long-handled roof rake to pull snow off the roof. This exposes the shingles to sub-freezing outdoor air and helps stop the damage caused by ice dams.

For more about fending off ice dams, please contact Roberts Heating & Air Conditioning. We’ve been serving the North Shore area since 1979.

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