The dangers of ice damming
By Amy Brown-Bowers • Bankrate.com

If you walk through your neighbourhood this time of year, you're bound to notice a fringe of icicles hanging from many roof edges. And if you live in southern Ontario, that fringe may be four to six feet long. While beautiful and festive-looking, icicles are often a sign of structural problems with your home and may indicate that your roof is being damaged.

Here is some information on what leads to icicle formation, what damage ice buildup can cause and how to deal with the problem.

Ice damming understood
"The most prevalent problem -- and it's probably the most misdiagnosed and misunderstood problem -- that plagues homes during the winter time is something called ice damming," says Jeff Clarke, president of Baker Street Home Inspection Services and a certified home inspector. "It's a roofer's worst nightmare, and it's actually not a roofing problem, but roofers get blamed."

Simply put, ice damming is when ice or snow melts, for various reasons, on your roof and then freezes near the overhang when it reaches what's called a cold spot, says Guy Battaglini, an executive member of The Ontario Association of Home Inspectors. Ice and icicles build up at the cold spot as more and more water freezes, forming a dam that blocks water from draining properly.

"As the snow keeps melting towards the ice dam and moving up, it's got nowhere to go but back up the roof," Battaglini says. "And where does it go? Underneath the shingles. And it starts saturating your wood frame member, which covers your roof and which your shingles are nailed to."