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Winter Ice Damming

Ice Damming 1 | Winter Ice Damming

As the weather warms in Calgary with the coming of Spring, one issue that many home owners have to deal with at this time of year – and we get a lot of calls for – can actually look beautiful, but obscures potential real dangers to a home: Ice Dam or some times called: ice damming.


What is an ice dam?

An ice dam is a ridge of ice that can be formed at the edge of a roof and prevents melting snow -accumulated over the winter – from draining off the roof. Unfortunately, the temperatures don’t tend to stay high consistently, and often will drop down to below freezing once night falls. This will cause whatever liquid has formed during the day to refreeze at night in the gutters and on the lower edge of the roof. This can create ice blockages that prevent moisture from draining properly and that build up over time.

Why should I be concerned?

If not addressed, ice dams can wreak havoc in numerous ways:

  • Added weight can potentially damage the building.
  • Falling icicles can also pose a danger to people walking below.
  • The water that backs up behind the dam can freeze beneath shingles or along weak seams, seep its way into the decking of your roof and causing rot or moisture damage to your roofing or insulation or further damage to the building.  Signs of this moisture may be seen in attic or on ceilings/walls of interior – see mold warning at bottom.

Oh – not Good! How can I prevent/fix this?

There are a number of ways to address ice damming – some interior, others exterior.  All have associated costs, advantages and disadvantages.  We recommend that if you are experiencing trouble with an ice dam – or suspect you see the symptoms of one – that you consult a qualified trades person as required.
Some possible remedies:

  • Ensure the ceiling in rooms below the attic are air tight so no warm, moist air can flow from the house into the attic space
  • Upgrade attic insulation and/or ensure there are no areas where the insulation may be patchy.  This will help regulate the attic temperature – reducing likelihood of creating an ice dam.
  • Ensure: no vents are clogged and/or there is sufficient soffit venting to allow sufficient venting of attic.
  • Keep in mind: Recessed lights, skylights, complicated roof designs, and heating ducts in the attic will all increase the risk of ice dam formation.
  • Employ a qualified professional to diagnose whether there is: sufficient venting of the attic through the roof/any vents that are being vented directly into the attic – this happens more than one would expect!


  • Removing snow from accumulating on the roof will certainly help – particularly with low-sloped roofs.
  • In some cases, adding a water tight membrane to the roof deck can help – consult a qualified roofer for more information.
  • In some cases a temporary fix can be to employ the use of electric cables to melt ice dam s.  Consult a qualified professional on this.

Ice Damming 2 | Winter Ice Damming


Ice Damming 3 | Winter Ice Damming

A Word of warning about mold

Moisture entering the home from ice dams can lead to the growth of mold and mildew. These biologicals can cause respiratory problems. It is important that the growth of mold and mildew be prevented. This can be done by immediately drying out portions of the house that are wet or damp and employing the use of a qualified mold remediator if necessary. By stopping an Ice dam you may prevent mold.

Home-Alyze Home Inspection Service will be happy to assist you if you have questions about ice damming!

home alyze | Winter Ice Damming

Give us a call at 403-295-3000, send us a text or email us


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