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Ice damming: What it is and tips to avoid it

Winter storms have cost Canadian homeowners up to $5.4 billion in property damage, including issues such as frozen pipes, water leaks and roof damage. So when the autumn leaves start changing, it’s a good time to turn your attention to winterizing your home, cottage or vacation property.

Even before the temperatures dip below zero, be on the lookout for signs and symptoms of potential trouble spots—like icicles. While they may appear Instagram-worthy hanging from the edge of your roof, it also indicates a problem: ice damming. And the damage could be costly.

What is ice damming?

Ice damming generally results from heat rising within the home and into a poorly insulated or poorly 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 further 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. And even though ice dams can form on roofs with little to no warning, many people don’t realize the hazard they present.

How can I 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, Mandaliti also 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, there are several maintenance tasks that property owners can perform on their own as well.

Fall maintenance

Check your gutters: This is a simple (and free) way to help reduce the severity of ice damming. Remove any debris, leaves, dirt and buildup from your eavestrough and downspouts so melted snow will be able to 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 relating to 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.

Winter maintenance

Some issues may not appear until after snow and ice have already built up on the roof. And if you’ve just moved into a new home, you may not be familiar with these issues until your first winter. For that reason, it’s important to know the red flags and conduct your own indoor/outdoor visual assessments throughout the season.

Indoors: Inside the house, look for any signs of water leaks that appear 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 pretty obvious: if you have chunks of ice on the edge of your roof, you have ice dams. You might also notice the roofline is sagging, there’s damage to the bottom row of exterior shingles or there are areas 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.

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 prevent damming, 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 to prevent or mitigate ice damming and other problems before they become much more extensive—and much more costly.


For more information and to ensure your insurance coverage fully protects your property, talk to your broker. 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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