Can You Always Spot an Ice Dam? Identifying Small Ice Dams, Ghost Ice Dams, & More
Let’s put your ice dam identification skills to the test. Of the 8 roofs in these photos, can you tell how many have ice dams on them?
Would you believe that every one of those roofs had an ice dam? All 8 of them. They were just of different sizes and on different parts of the roof.
The first photo probably looked pretty obvious, given the size of the icicles. You probably had a feeling about the house in the second photo.
#3 and 4 may have surprised you, because it’s a pretty small amount of roof surface area showing in the photos, with a relatively small amount of snow, and because you may know that icicles on your overhang don’t necessarily mean you have an ice dam. These are just small ice dams (more
#5, 6, and 7 may have thrown you, because each overhang just looks like it has a thin layer of snow on it, or (in the case of #7) no snow at all, and no ice dam. You’d be accurate in observing that: In each photo, the ice dam is several feet up the roof.
How about that last photo? By Gum, it looks like just another snowy roof. How can you possibly tell there was an ice dam under there? You can’t. We can’t, either. We only knew there was an ice dam on that roof because the homeowner called us and said the roof was leaking. We couldn’t drive by the house on our way to another job and say, “Bet we’ll get a call from those people soon.”
Ice dams can be small. Small ice dams don’t tend to cause problems to the same degree huge ice dams do, but they’re big enough to cause roof leaks and all the problems that can accompany roof leaks. Also, once you have a small ice dam, the only thing preventing it from getting big is more snowfall. If you get more snow, and especially if the temperatures stay low, then your ice dam can go from Pop-Warner-sized to a 340-lb. NFL defensive tackle.
Ice dams don’t even require much snowfall. Sometimes an inch of snowfall is all that’s needed to form an ice dam, depending on how the snow melts. Keep in mind where ice dams most often form – on or near the overhang – and that even a one-inch layer of snow covering a roof is a lot of snow if you gather all of it into a pile. Now picture that pile slowly melting and rolling down your roof. It’s that amount of water that can refreeze on your overhangs and form an ice dam.
If it’s cold enough, you may not see any icicles, or the ice dam may form higher up the roof. That’s because any given part of roof just needs to be slightly below freezing for water (i.e. melted snow) to refreeze on it. The overhangs are the coldest, because they don’t receive direct attic heat from below, but even a part of your roof that is over the attic can dip below freezing, in which case the water may never even make it down to the overhang. That’s why you can have an ice dam and not only not see icicles hanging off your overhang, but also not even see any signs of other ice on your overhang.
Ice dams that form several feet up the roof are what we call “ghost ice dams.” We call them that because you can rake all of the snow off of your overhangs, not see any ice there, and assume you don’t have an ice dam – only to experience more roof leaks because the ice dam is several feet up the roof. In these cases, the ice dam only reveals itself if you remove all of the snow from the roof. Photos #5-8 (above) are good examples of ghost ice dams.
In many cases the only way to find the ice dam is to uncover it by removing some or all of the snow from your roof. We’re not saying you should remove the snow personally. Unless you want to cancel your gym membership and instead get jacked arms by pushing yourself around in a wheelchair, then you should hire someone with the gear and the hours logged on rooftops.
Not every big ice dam causes roof leaks, and small ice dams are less likely to cause leaks. But what you should not do in the winter is notice what seems like a roof leak, look at your roof, conclude “It’s just snow – doesn’t look like an ice dam” and then not get the ice dam removed. It’s almost certain you do have an ice dam, and it’s small enough to fly under your radar, but big enough to cause your roof to spring a leak. Either that or it’s a ghost ice dam. You won’t know where it is until you have the snow removed – either by your hand with a roof rake in it, or by a trained, licensed, insured, and experienced ice dam removal technician. You probably won’t enjoy paying for ice dam removal, but you’ll have the satisfaction of saving yourself potentially many thousands of dollars in repairs, and of following an educated guess that was right on the money.