How Long Until Your Ice Dam Melts Naturally? Factors to Consider

If you’ve got an ice dam on your roof, you probably want to know how long you’ll be stuck with it.  Maybe it formed seemingly overnight, or you just noticed it, or it’s been on your radar for a couple of weeks.  In any case, you want as many facts and as much other intel as possible.  You want at least a rough sense of how much longer your ice dam will loom over you, so you can plan and adjust.  

If you don’t know whether it will take days, weeks, or months for your ice dam to melt on its own, you can’t plan.  You don’t know whether or when the ice dam will cause a roof leak and maybe other problems, and so you don’t know whether you might be able wait it out or will need to call a professional ice dam removal company.  You want to be home in case there’s a trouser-darkening event that requires your attention, but you do have other obligations and can’t put your entire life on hold.  Are you in for Operation Desert Storm, or the Battle of Stalingrad?

Every situation is different, no roof is immune to ice dams, and we haven’t seen your roof.  So for now all we can do is tell you the variables that can keep your ice dam around for a longer time.  You might call these risk factors.  A doctor might call them comorbidities.  The more of these factors are true of your situation, the less likely it is your ice dam will melt naturally, and the more likely it is you’ll need it steamed away.

1. Did you leave the snow on your overhangs?  Sometimes that’s all it takes to prevent the initial formation of ice.  Also, that’s the easiest way to give Mr. Golden Sun a nice, clean, dark patch of roof that can collect heat and melt some of the snow and ice sooner rather than later.  If you didn’t clear your overhangs (and maybe some of your valleys) while the only thing on them was snow, then all of the snow above the overhangs may soon become food for your ice dam.

2. Do you have asphalt shingles?  Most people do.  Asphalt shingles don’t inherently make an ice dam more likely to form in the first place, but their coarse granules do make snow and ice more likely to stay put rather than to slide off.  Standing seam (metal) roofs can get ice dams, too, but even when an ice dam forms it is more likely to glide pop right off of the roof and glide to the ground.

3. Do you have a shallow-pitch roof?  Like a 6/12 pitch or flatter? The steeper your roof, the harder it is for snow to gather in the first place, and the easier it is for any runoff to make it to your gutters rather than linger on the cold overhangs.

4. Does your roof have high square footage? This isn’t always the same as having a large home, in that some large homes have relatively little surface area taken up by the roof (roughly 1/2 to 1/3 the square footage of the home), while some ranch-style homes have a roof with a higher square footage than that of the house.  In simple terms, the larger the roof, the more opportunities there are for snow and ice to gather in troublesome spots.

5. Do you have a complex roofline, with lots of valleys, transitions, and penetrations? If you have dormers, cupolas, monitors, or an addition, the snow is likely to form drifts, melt, and form ice dams.  Likewise if you have roof penetrations for a chimney, vent pipe, box vent, or skylight.

6. Do you have a finished attic? If someone’s living up there, it’s much harder to insulate your attic enough to keep it cool and keep it from melting snow left and right.  You’re pretty much guaranteed constant heat loss, meaning that any snow is likely to become an ice dam quickly or worsen an existing ice dam quickly.

7. Does one slope of your roof face north (due north or mostly north)? Some part of every roof faces north, of course, but in general it’s better if the sun can slowly work on a piece of each slope of your roof, rather than leave a thick blanket of snow on one side of your roof – snow that can only melt from the bottom, due to the hot shingles.  Often we’ll see the south-facing slope of a roof with no ice dams or even snow, while the north slope of the same roof is still covered in snow and leaking like a sieve.

8. Is your home right next to a much taller building?  This is a common problem in older neighborhoods, where a 1 1/2-story home might live in the shadow of a triple-decker.  The abutter prevents the sun from chewing on your ice dam, which also means you probably need to turn up your heat even more, which may accelerate the growth of your ice dam.  To add insult to injury, snow that blows off the taller home is likely to land on your home.

9. Do you have lots of trees in your yard or adjacent to it? Not only can the shade keep your snow and ice from melting, but the trees can also deaden wind that can blow some of the snow off of your roof.  Evergreen trees are especially likely to block out the light and the wind.

10. Is your roof still covered with snow? Even if you already have an ice dam, if you can get rid of some of the snow, you can at least slow down the growth of the ice dam and maybe give the sun a chance to help you out.  But if you saw the snow, let it become an ice dam, saw the ice dam, and then let it feed itself on more snow, then your ice dam will probably get worse before it gets better.

11. Is there more snow on the way? As little as an inch of snow, if allowed to sit on your roof, can cause even an ice dam that’s on its way out to stick around for a couple weeks more.

If you answered “yes” to more than about half of those questions, the chances are high your ice dam will be around for weeks or more.  It might not spring a leak today, tomorrow, or next Tuesday, but it’s unlikely to go away in that time, either.  The bad news is you’ll probably need to fork over for professional steam-only ice dam removal.  The good news is you’ll probably save yourself from even costlier repair bills, get instant peace of mind, and know what you’re in for next winter.