I have been searching for a solution to the almost annual breaking off of my toilet vent stack on our metal roof due to significant winter snow accumulation. Yes, having the snow removed is the right thing to do. However, I offer up options to ultimately correct the issue: build a 24-inch iron A-frame, welded and mounted via screws to the metal roof above the stack; install an electric warming wire to promote melting thus avoiding the snow and ice buildup in the first place; relocate the toilet vent stack closer to the peak edge of the roof, or reroute it. Would one of these solutions be effective?—D.B., Masham, Que.
Sorry. We couldn’t get any of the building or roofing experts we talked to give your solutions a truly enthusiastic thumbs up. Plus, Paul Grizenko of PRS Roofing in Pointe-Claire, Que., suspects that your ice buildup vs. vent stack problem might be caused by heat loss through the roof, from either a lack of insulation, a lack of ventilation, or both. So anything else you try may just be a band-aid solution.
Insulation upgrades to keep your cottage cozy this winter
Still, out of all of your ideas, blocking the snow could be a workable option—though DIYing a structure yourself isn’t necessary. There are already a number of products designed to block snow and ice.
Snow has been falling off metal roofs since the dawn of the metal roof. “Metal is a slippery slope,” says Troy Ferreira, the technical director for the Canadian Roofing Contractors Association. He’d suggest a “cricket”: a diamond-shaped hump installed above the vent stack, intended to divert the snow.
Grizenko, on the other hand, would suggest a snow fence: a set of horizontal metal bars bolted to the roof with L-shaped brackets. (The next time you’re walking into a shopping centre, look up: “You often see them mounted above the entrances,” he says.)
Anything you attach to the roof should ideally be bolted to the rafters underneath. You’ll have to pierce the surface of the roof to install the bolts. No surprise: “This can result in roof leaks,” says Grizenko. “The solution is to use a combination of waterproofing, butyl tape, and UV-resistant caulking. It can be done, and it can work,” he says. But it still may not be “a forever solution.”
Retrofitting a metal roof with any kind of snow guard or snow fence—whether you build it yourself or buy it—is tricky. The right strategy is going to depend on a number of factors, including the slope of the roof and the type of metal roof. You’re best to get the input of someone well-versed in metal roof attachments, says Ferreira; he recommends the folks at S-5!, a company that specializes in them.
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This article was originally published in the Winter 2021 issue of Cottage Life.