Beginners Guide to Ice Dams: Causes, Signs & Removal

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Ice dams. These icicles on your roof may appear harmless – and may even look pretty – but they can cause damage to your home. Here’s what you need to know about protecting your house from ice dams.

What is an ice dam?

An ice dam is a wall of ice that forms at the edge of the roof, typically at the gutters or soffit, and prevents melting snow from draining off.

What causes ice dams?

For an ice dam to form, 3 things must be present:

  1. Snow on the roof
  2. Higher portions of the roof’s external surface must be above 32°F
  3. Lower surfaces must be below 32°F

When these factors are in play, snow will melt and the water will flow down the roof and eventually freeze – forming an ice dam.

Poor ventilation and temperature control in the attic can also lead to ice dams. Excessive warm air in the attic can cause the snow on the roof to melt regardless of the temperature outside. Recessed lighting, skylights, complex roof designs and heating ducts in the attic can all increase the chances of an ice dam developing.

Do icicles mean that you have an ice dam?

In short, no. It’s common for small icicles to form; the larger, thicker icicles are the culprits. When you notice the larger icicles, it’s important to act fast in order to prevent damage.

What are the signs that you have an ice dam?

These are the most common, according to the Ice Dam Company:

  1. Your home has a history of ice dams
  2. Icicles form on the edge of the roof or off the front edge of the gutter
  3. Ice is coming through the soffit
  4. Ice is forming behind the gutters
  5. Water or ice appears on the exterior wall
  6. Water is seeping through a door frame or window

What type of damage can ice dams cause?

If not addressed early, ice dams can cause significant damage. Here’s how:

  • Water from melting snow can seep into your house and into walls, ceilings, insulation and other interior areas.
  • Ice dams can lift roof shingles up, allowing water to leak inside your home.
  • Pressure and weight from the dams can pull off gutters and lead to structural damage that can cause flooding.
  • If attic insulation gets wet, it can become ineffective, plus mold can develop.

How to prevent ice dams:

Consider these precautions.

  • Have your gutters cleaned before winter.
  • Keep your attic well ventilated, so it stays cold, and properly ventilate the roof and eaves.
  • Insulate the attic floor to reduce the amount of heat rising from within the house.
  • Rake or shovel snow off the roof before it freezes or hire a professional roofer to clear your roof.
  • Create an air barrier between the house and attic with a foil-faced cover over an uninsulated attic hatch or whole-house fan opening.
  • Install a water-repellent roof membrane.
  • Check for any potentially dangerous heat sources, including uninsulated recessed ceiling can lights, uninsulated folding attic stair openings, heating ducts, furnace or water-heating equipment and inadequate bathroom vent fans.

How to remove ice dams:

If an ice dam has formed, here are immediate steps you can take to help prevent further damage.

  • Apply calcium chloride or another ice-melting product onto the ice.
  • Place a box fan in the attic and direct it at the underside of the roof where water is leaking in. The cold air will freeze the water.
  • If your roof is flat or has a low slope, use a sturdy push broom with stiff bristles to sweep off the snow.
  • Have a professional remove the dam with high-pressure steam or other specialized methods.

When it comes to removing snow or repairing ice dam damage on your roof, always consider your personal safety.