Don’t See Icicles? You May Still Have an Ice Dam
As I’ve written, icicles are a pretty reliable indicator of how serious your ice dam problem is. But just because you don’t have icicles does not mean you don’t have ice dams.
Icicles are just a warning sign, and they’re a pretty good one at that, because the root of most substantial icicles is an ice dam. (Some of the same water that pools behind an ice dam can leak past the ice dam and form an icicle.) But it’s possible to have a “root” and not a “branch” (think poison ivy).
We call them “ghost dams,” because they’re hard to see. They’ve got no (or very small) icicles. They’re almost entirely covered by snow. You might not see them at all, and we might not see them until we actually get on the roof and remove some the snow that’s covering them. (That’s one reason we can’t tell you how long your ice dam removal job will take.)
If you’re lucky, you might see a thick band of ice along the overhang that looks like an ice cream sandwich. If you’re unlucky, your ghost dam will find its home in a roof valley where you’ll never find it.
When do “ghost” ice dams form? Typically when it’s bitterly cold, especially when the daytime highs don’t get anywhere near freezing, let along above freezing. In a winter like that, expect a visit from a ghost.
Where do “ghost” ice dams form? Typically right at the point you stopped raking your roof (because you couldn’t or didn’t reach up the roof any higher). They’re especially likely to form in the places you didn’t rake (e.g. the roof valleys). Be vigilant of ghost-dams if you raked your roof but were unable to get all of the snow off, and a thick blanket of snow still resides atop your roof.
As luck would have it, the higher-up areas of your roof are the most likely to spring a leak, because it’s the area least likely to have ice and water shielding under the shingles.
It’s also the most likely to be blanketed with new snow, hiding it even more – especially if you got several small snowfalls that didn’t put you on red alert. It only takes 3 two-inch snowfalls to create 6 inches of snow (and probably more like 8-12” in the drifts).
Ghost ice dams can also haunt homeowner who are just plain unlucky. 90% of the time, though, if you do get a ghost dam, you’ll at least be lucky enough to get the telltale “ice cream sandwich” on the overhang (whether or not you notice it). Most ice dams form on those darn overhangs. You just need to train yourself to act when you see that thick, bluish band of ice, regardless of whether you also see icicles. Otherwise you’ll get caught off-guard when the leak starts. Keep ice dam removal in your budget – just in case.