Ice Damming Prevention

Ice dams are a fact of life in snowy areas of Calgary, but they can be reduced and even eliminated with proper insulation and venting. Here’s how to tackle the problem!



Lets Talk A Little About What Ice Dams Are


If you’ve looked outside recently, you’d definitely agree that winter is here – along with it one of your home’s worst enemies—ice dams. Ice dams are continuous chunks of ice that form along the margins of your roof. While frozen, they’re no more trouble than the icicles that hang down. But during the warmer parts of a winter day, which we all know we have in Calgary – water melting off the roof pools behind the ice, then seeps back up under the shingles. Sometimes water can even work its way 5 -10 ft. back up under the shingles. Eventually it drips through the roof into the soffits (the outside overhangs), walls, and worst of all, onto your ceilings. Insurance companies pay millions of dollars to thousands of homeowners annually to repair the damage. But it’s never enough to cover the time and aggravation of getting everything fixed…so why not avoid it where you can?


Now is the best time to stop ice dams, before winter comes and before they build up. In this article, we’ll tell you the best ways to prevent ice dams.


The key to preventing ice dams is simply to keep your attic and roof cold. After a snowfall, a cold roof will have a thick blanket of snow. A warmer roof, however, will soon have clear spots where the snow has melted off, and may well have icicles hanging from the eaves. If you think you are at risk, give the Roof Hospital a quick call, we’ll be happy to come talk things through with you.

To keep your roof cold, follow these three steps:


1. Close up attic bypasses
In the average home, about one-third of the heat loss is through the ceiling into the attic. And most of that loss comes from air leaks caused by unblocked walls, gaps in drywall, and cracks around light fixtures, plumbing pipes, chimneys, access hatches and other ceiling penetrations. Air leaks can be tough to stop. If this is the case we would recommend calling a roof expert to pull or rake back insulation, and plug the leaks using foam, caulk and other methods. 

Bonus: By stopping air leakage to mitigate ice dams, you’ll save energy and reduce both your heating and your air conditioning bills.

2. Measure your attic insulation level
While you or the roof expert is in the attic, check the depth of your attic insulation. Building codes require about 12 to 14 in. of fiberglass or cellulose. Add more if you have less than 8 in. and have had ice dam problems in the past. Blown-in cellulose and fiberglass are usually better than hand-placed batts, because they fill more tightly around rafters, joists and other obstructions, leaving fewer gaps. It’s usually worth hiring a professional for this job; you probably won’t save much by doing it yourself. 

3. Add roof and soffit vents
Attic ventilation draws in cold outdoor air and flushes out warmer attic air, cooling the attic and the roof in the process. The minimum ventilation area (size of the openings) should be about 1 sq. ft. of vent per 300 sq. ft. of ceiling area (attic floor area), when half the vent area is low on the roof and half is high. Actually figuring all this out is a bit complex; you’d have to examine your existing vents to find the area of each, which is stamped on them. We never recommend cutting a hole in your own roof yourself, so give the professionals a quick call to quote you for a few more vents to take care of the issue. 


For any roofing inquiries or expert advice, please don’t hesitate to call the Roof Hospital.


Where Clients Come First, On And Off The Roof.