I recently got an email from a homeowner complaining about ice damming on their roof last winter. It was so bad it caused major damage to their ceiling — they even had to replace walls.
It’s a good time to review ice damming because if you can fix the problem now, before winter moves in, you could save yourself a ton of money and grief.
Most people tend to think that ice damming means there’s a problem with their gutters. Nine times out of 10, ice damming is not an eavestrough issue, it’s an attic issue.
If your eavestroughs are clogged with debris and leaves, water won’t drain properly. And once temperatures drop below freezing, all that trapped water and debris will turn into a frozen channel of muck. Next thing you know, you have ice damming all along your roofline, which can lead to water backing up underneath your shingles and getting into the roof structure, possibly causing water damage to the roof deck.
Then soon you’ll be looking at things like rot and mould.
That’s why fall maintenance must include clearing your eavestroughs of any debris now — because no one knows when temperatures will drop or how quickly.
But the real source of ice damming is usually heat loss in the attic.
Ice damming occurs when there is a constant cycle of snow melting and freezing. But snow shouldn’t melt when the temperature outside is below freezing, right? So what’s going on?
The snow on the roof is melting because heat is escaping through the attic, and as the water drains down the roof to the roofline, it refreezes because the overhang is colder.
Heat shouldn’t escape from your attic; it’s supposed to be a cold zone, the same temperature as outside.
To keep the attic a cold zone, it should be properly sealed off from the rest of the home with vapour barrier and a minimum of 12 to 15 inches of blown-in insulation. (Vapour barrier helps stop drafts and moisture from getting into places it shouldn’t.) It’s also important to make sure your vapour barrier is properly sealed with Tuck tape.
If any part of this system doesn’t work the way it should, problems such as heat loss, ice damming and even mould will occur.
Then make sure there’s enough ventilation, with fresh air coming in through the soffits and going out through the venting on the roof.
If any part of this system doesn’t work the way it should — for example, if the soffits are blocked by insulation, the vapour barrier isn’t properly Tuck taped or the venting on the roof is covered by snow — problems such as heat loss, ice damming and even mould will occur.
One homeowner tried to solve his ice damming issues by replacing the soffits. That didn’t work, so he asked if spray foaming the underside of his roof could help.
If you’re going to spray-foam your attic — and I love closed-cell spray foam — it should be applied to the bottom area of your attic space (or your ceiling, behind the drywall, if it’s a finished space) to properly seal off the environment below. And the great thing about closed cell spray foam is that it’s also a vapour barrier, so you get two in one.
Now is the best time to get a professional to come to your home to look at your attic and make sure it’s doing its job. I’d even recommend getting a maintenance inspection, because if you need any repairs before winter, especially to your home’s building envelope, you still have time to get the job done right.
Stay ahead of the game and make sure your home is ready for another round of winter weather. You’ll thank yourself later.
Watch Mike in his new series, Holmes Makes It Right, on HGTV. For more information, visit makeitright.ca