Ice Dams: An All-Too-Common Roofing Hazard in Quebec

Do memories of the 1998 Quebec ice storm still make you shiver? Are you dreading winter and the inevitable formation of an ice dam on your roof?

Never fear, Les Couvreurs Duro-Toit are here! Below we explain exactly what causes ice dams, how they form and how you can prevent them. Grab your warmest tuque and let’s go!

What causes ice dams?

The best way to avoid the dangers of ice dams is to know why they form in the first place. In Quebec, the most common causes of ice dams are:

1. Poor insulation: poor attic ventilation causes heat to rise to the roof. The warm temps cause the snow on your roof to melt and eventually freeze into an ice dam. If attic insulation is to blame for your ice dams, our experienced roofers can identify and fix it.

2. Mild days and freezing nights: temperatures that are just above freezing during the day and sub-zero at night create a freeze-thaw cycle. This can lead to ice build-up on your roof.

3. Heavy snowfall: small patches of snow on your roof are nothing to worry about. The danger comes when 4 to 6 inches of snow piles up on your roof and temps are sub-zero…a.k.a. a typical Quebec winter. Les Couvreurs Duro-Toit explain how to calculate the weight of snow on your roof.

How ice dams form: a 5-step process

1. Snow piles up
2. Heat escapes through the roof
3. Snow melts
4. Water freezing and ice build-up
5. Water leaks into the attic

Step 1: Snow piles up

First and foremost, there must be a sizable amount of snow on your roof. Contrary to popular belief, freezing rain is only one of many ice dam causes. Large amounts of snow build-up are the basis of ice dam formation.

<H3> Step 2: Heat escapes through the roof

The next requirement is heat loss through the roof. If your home is poorly insulated and ventilated, the heat will flow from the interior of the house and escape through the attic. This causes a significant temperature imbalance between the inside and outside of the house.

A sure sign of this? Icicles forming on your roof gutters and eaves.

Step 3: Snow melts

The heat rises, warms the roof and inevitably causes the snow on the roof to melt. This water then flows to the lower parts of the roof, where it freezes into a dam.

Step 4: Water freezes and ice builds up

Water freezes along your roof edges because it is the only part of the roof that isn’t warmed by the attic. Water accumulates there and refreezes if outside temps are below zero. This cycle repeats until massive solid blocks of ice form on the roof.

Note that these ice blocks may be covered by snow and therefore not visible at first glance. One clue, however, are icicles on your gutters and eaves. Despite their beauty, these ice formations are a sign to schedule a professional inspection.

The weight of all this frozen water can weaken the roof structure, increasing the danger of collapse.

Step 5: Water leaks into the attic

If you don’t have the snow and ice removed from your roof quickly enough, this build-up can cause serious damage. There is a particularly high danger of leaking.

The newly melted snow gets caught between the thin layer of ice and the roof covering. As a result, it seeps into the shingles and leaks through the attic. The water’s evaporation/condensation cycle can also increase the risk of leaks.

The water will then spread from the space under your roof to your home’s ceiling, walls and floors, causing significant water damage.

How to prevent ice dams

To prevent ice dams forming on your roof, you should use a combination of the following 2 methods:

1. Heated de-icing cables: heated de-icing cables can greatly decrease the risk of ice dams on your roof. They are placed along the eaves, skylight, chimney, gutters or drain pipes. However, this electric heating solution is not always enough to get rid of ice dams. It’s often necessary to get the snow removed and prevent them from forming in the first place.

2. Roof snow removal: removing snow from the lower parts of your roof is a simple and effective way to prevent ice build-up. You could try to remove the snow yourself, but it’s best to call in experienced roofers. Their professional equipment and techniques are the only guaranteed ways to prevent serious leaks and water damage.

Les Couvreurs Duro-Toit: protecting roofs throughout Greater Montreal

Don’t wait until it’s too late! If you have any doubts that your roof is winter-ready, contact our experts ASAP. The health and well-being of your family may depend on it!

In addition to snow removal services, we can also conduct a roof inspection before winter. When it comes to making sure you’re warm and cozy for winter, Les Couvreurs Duro-Toit have you covered! Contact us by phone at (514) 755 – 8648 or fill out the form on our contact page!


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