Understanding Ice Damming

Preventing Ice Damming On Your Property

Alberta is home to some of the most diverse weather patterns in the world. If you’ve heard the saying, “If you don’t like the weather, wait ten minutes”, you know just how true that can be. Not only can the weather change rapidly in the summer months, the freeze-thaw cycle in the winter months can be just as erratic. Warm temperatures, melting snow on a January afternoon, can suddenly drop thirty degrees by evening, freezing everything solid, only to warm up again a couple of days later. But while the winter freeze-thaw cycle can play a part in causing ice dams, the main cause of an ice dam is actually heat loss from inside the house.

The term ice damming is used to describe the build-up of ice along the sloped roof eaves of a house or building during winter. It will usually occur on roofs with a thinner roofing material, such as an asphalt shingle. An ice dam will form when a warm roof surface allows snow on the roof to melt and then later freeze, causing ice to form directly on the roof. As this cycle happens more and more, the ice dam increases in size, causing the free flow of melting snow to stop. The resulting water backup forms on the roof above the dam, which works its way underneath the roofing material as it continues to melt and freeze. The ongoing struggle with an ice dam problem is not only frustrating, but can be very costly. If an ice dam problem becomes serious, it can cause rotting wood sheathing and framing, render attic and wall insulation useless, and create mold growth in walls and ceilings.

Preventing Ice Damming

Even though we can’t change the weather in Alberta, there are several steps that you can take to prevent ice damming from occurring on your home.

1. As snow builds up throughout the winter, you can use a roof rake to carefully pull snow down to the ground from the bottom 3 or 4 feet of the roof at the eaves. Be careful not to scrape the shingles with the rake, loosening the protective granules. A roof rake is kind of like a backwards shovel that comes in approximately 20 foot extendible lengths. It is a much safer way of removing snow than getting on the roof with a shovel.

2. Ensure that your soffits are open and clear of debris and insulation so that cool dry air can enter the attic. As well, ensure that you have adequate venting at the roof peak of your home to allow warm moist air to escape. These vents at the roof peak will need to work in conjunction with the open soffit intake venting to create a proper, even air flow.

3. Have an Ice and Water Shield membrane installed at the eaves and in any valleys of your roof where ice damming can occur. These membranes are made with Styrene Butadiene Styrene (SBS), a durable rubber material that works kind of like a band-aid, helping keep water out of the attic area.

4. Most importantly, have your attic insulation inspected by a reputable insulation company. They can recommend adding enough insulation to prevent heat loss from your home. If they do add insulation for you, ensure that they do not cover the soffit area, blocking the cool dry air from entering the attic area.

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