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Ice damming: What it is and tips to avoid it

Winter storms have caused many problems for Canadian homeowners, including issues such as frozen pipes, water leaks and roof damage. So when the autumn leaves start changing, it’s an excellent time to make sure your home, cottage or vacation property is ready for winter.

Even before the temperatures dip below zero, look for signs and symptoms of potential trouble spots, like icicles. While they look beautiful, it also indicates a problem of ice damming. 

What is an ice dam?

Ice damming generally results from heat rising within the home and into a poorly insulated or ventilated attic space. This heat melts the snow and ice on the roof, causing meltwater to run down the roofline. When the water contacts the cold edge of the roofline, it then refreezes and creates an ice dam.


This trapped water backs up beneath the shingles and eventually works its way inside the home through the ceiling and walls. Untreated, this cycle will repeat itself throughout the winter months, with the potential to cause significant damage.

While ice damming is more prevalent in parts of the country that get a lot of snow and experience extreme temperature fluctuations (like Winnipeg, for example), it could happen anywhere in Canada, given the right circumstances. An ice dam can form on roofs with little to no warning, many people don’t realize the hazard they present.

How to prevent ice dams?

In winter, you might also wonder why your roof has so many icicles compared to your neighbour’s house, even though your homes look similar.

“There are two big culprits: poor insulation and ventilation,” says Dom Mandaliti, Personal Insurance Loss Control Manager with Wawanesa. “Homeowners can typically spot issues, and prevention is key. But it starts before the first snowfall of the year, and you should continue doing periodic inspections throughout the winter,” he advises.

While homeowners can identify a problem such as an ice dam, Mandaliti recommends calling professionals for support. “Consider picking up the phone and getting a contractor to do any substantial repairs. And if you’re getting close to completely replacing your roof covering, talk to your contractor about whether your house has adequate ventilation,” he explains.

While some issues, like poor insulation, require time, money and expert help to fix, property owners can also perform several maintenance tasks independently to help with ice damming prevention.

Fall maintenance for ice dam prevention

Check your gutters: This is a simple way to reduce the severity of ice damming. Remove any debris, leaves, dirt and buildup from your eavestrough and downspouts so melted snow can drain freely. But make sure you take safety precautions. If you don’t have a family member or friend to spot you while using a ladder (or don’t feel comfortable using one), call a pro for help.

Consider a professional inspection: If you have any concerns about ice damming, contact a qualified contractor to conduct an inspection. As part of their professional assessment, contractors should review conditions involving adequate attic insulation, sufficient attic ventilation and roof cover conditions, among other things which could cause an ice dam.

Winter maintenance for ice dam prevention

Some issues may not appear until after snow and ice have already built up on the roof and caused ice damming. If you’ve just moved into a new home, you may not be familiar with these issues until your first winter, which is why you should conduct your own indoor/outdoor visual assessments throughout the season.

Indoors: Inside the house, look for signs of water leaks on the ceiling areas or walls. Search for water stains or discolored damp areas, cracks in drywall, mold forming on drywall (particularly where the wall meets the roof) and even doors that don’t close properly.

Ice outdoors: Ice damming is obvious: if you have chunks of ice on the edge of your roof, you have an ice dam. You might also notice the roofline is sagging, damage to the bottom row of exterior shingles or where icicles seem to form regularly. Once you’ve identified that you have ice damming, your best option is to contact a professional contractor to remove the snow and ice. Contractors may also be able to assess the need for repairs or improvements to prevent future ice damming from occurring.

Snow buildup: Be aware of the amount of snow on your roof and where it’s accumulating. Once again, if you notice excessive accumulations, consider contacting a professional contractor to remove that snow safely. A roof rake is also a safe way to help clear snow from the edges of your roof. Note that you should only use roof rakes to remove snow from areas that are safely accessible from the ground.

What to do when replacing your roof

At some point, you’ll need to replace your roof covering, which is an excellent time to look for opportunities for improvement. A key enhancement to consider is the installation of a waterproof membrane at the edge of the roof, below the roof covering. It won’t guarantee ice damming prevention, but it will prevent damage. Even better, you could install a waterproof membrane over the entire roof, which would provide optimal protection at minimal added cost.

“Use a manufacturer’s certified or authorized roofing contractor since they’ll do everything by the code,” says Mandaliti. “They’re not just putting shingles on roofs—they’ll look at ventilation and will identify problem spots. Someone who’s certified might cost a bit more money, but they could save you money in the long run.”

The bottom line is that staying on top of roof maintenance can help with ice dam prevention to avoid extensive and costly damage to you home.


Talk to your broker for more information and to ensure your insurance coverage fully protects your property. They are ready to assist if you have any questions.


Read next: 10 ways to protect the roof over your head



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