Ice Dams on Your Roof: How to Prevent Them

Icicles hanging from the edge of a residential roof
Ice dams cause some of nature’s most beautiful sights — icicles — but they also wreak havoc on your home. (DepositPhotos)

If you’re fortunate enough to live in the Sunbelt or some other balmy region, chances are you’ve never heard of — or at least experienced — ice dams.

I, on the other hand, live in New England, so every winter, ice dams are as common — and as welcoming — as frostbite and sub-zero temperatures.

That’s because ice dams can be problematic, destructive, and virtually impossible to remove once fully formed.

Ice dams on house in winter
Ice dams lead to icicles. (DepositPhotos)

Ice Dams: Beautiful, But Problematic

Ironically, ice dams are often responsible for one of the most beautiful and iconoclastic of all winter images: glistening crystal-clear icicles hanging from gutters and eaves.

Heck, even I marvel at the delicate beauty of icicles — but only when they’re hanging off someone else’s house.

So, what causes ice dams?

It all starts with a roof blanketed in snow. The snow layer sitting directly on the roof begins to melt, and water runs down the roof under the blanket of snow.

When the water hits the overhanging eave of the house, it begins to freeze. Some water drains into the gutter, where it freezes as well.

As the snow continues to melt and water freezes at the eave, ice eventually builds up along the roof, forming a thick ridge or dam.

Then, as water runs down the roof, it’s blocked by the ice dam, and forced up the roof.

I know it seems to defy all laws of physics (and commonsense), but water will actually flow up the roof, working its way under the shingles.


  1. We have a flat roof only over my office in our home.We had a leak so we had a copper roof put on they said it will never leak,guess what it does and the roofing compancy will not do anything about it. It only leaks when it snows or when ice melts then it come from the celing and drips into my office.It’s a ice dam. We have know attic its just a flat roof.My husband has gone out on the roof and shovel the ice off he can’t keep doing this he is 71 years old.
    What can we do next if anything?
    We do not get your show. so can you email me and tell us what to do if anything.

  2. Dear Gloria, I’m sorry to hear about your roof leak. Flat roofs are notorious for leaking, which is why you see very few of them. The first suggestion is to please keep your husband off the roof. That’s no place to be, especially when it’s wet and/or covered with snow and ice. It’s hard to give specific advice without seeing your roof, but I suspect it doesn’t leak during a rain storm because the rain runs off. But snow and ice sits up there and melts slowly, where it gets a chance to seep through seams and joints between the copper roof panels. The problem isn’t with the roof itself, but the way it was installed. Any roof system will leak if improperly installed or damaged. Your only option is to call a professional roofing contractor and have them inspect the roof for punctures or ill-fitting joints. The contractor should also closely inspect flashing or vent pipes, if there are any. Another common place for leaks is where one roof meets another roof or the side wall of the house. Sorry I can’t be more specific, but an experienced contractor will certainly be able to locate and fix the leak. Thanks for writing and good luck.–Joe T.

  3. Thanks for providing great information for us home owners. We just moved into a 40 year old home with lots of leaks. I noticed today the ice dam on and around the gutters. I know we lack enough insulation. I have watched the other videos on how to instull and how much. I think I am not ready to tackle this job. Appreciate the easy and simple use of this website too. blessings from Grove City Ohio

  4. Hey Tim, Glad you like the website and found the information on ice dams useful. Hope all is well in Grove City. As you mentioned, the lack of attic insulation is likely the main cause of your ice dams. And when you do add insulation, be sure you don’t place it in too close to the eave. You must leave space for outside air to flow through the soffit vents, up between the rafters, and out the ridge or gable-end vents. Maintaining an efficient attic-vent system is the best way to combat ice dams. Thanks for writing and good luck!–Joe T.

  5. We have just survived the Great Blizzard of 2013 here in R.I. and today it is raining! Thank you for your great article on ice dams & how to prevent,plus your information on insulating the attic. Plan on being very busy; can’t wait for spring.

  6. Hi, can you tell me the better choice for insulation in the attic?
    My brother is pushing me towards blown in, where we buy the packages and get the blower from the home store. Sounds easy, less stress on us to crawl around placing rolls or batts in the attic.

    I think we lay down our exacts with rolls or batts, meaning I buy R30, lay it down and there we go,

    I can not tell price-wise which is saving me money. My sq ft is 910 I need covered, any help is very much appreciated

    thanks, tim helsel in Ohio

  7. Hi Patricia, I feel your pain. I live in Connecticut and we’ve gotten a ton of snow this winter–with more to come, I’m sure. Glad you liked the article on ice dams. Increasing attic ventilation is key, but it’s also helpful to remove snow from the edges of the roof with a roof rake. I bought a roof rake online that has an extra-long handle, which allows me to pull off the snow while standing safely on the ground. Good luck, Patricia and hang in there, spring is coming!–Joe T.

  8. Hi Tim, I am not familiar with insulation costs in Ohio, but it’s typically cheaper to buy fiberglass batts and lay them down yourself, as opposed to renting a blower and buying blow-in insulation. Of course, as you mentioned, it is much more work to cut and lay down each individual batt than to simply blow in the insulation. Regardless of which type of insulation you install, be sure you don’t block the air flow from the soffit vents, assuming you have soffit vents. It’s important to allow fresh air to enter the attic at the eaves and exhaust out the ridge vent or gable end vents. Sorry I couldn’t be of more help. Good luck.—Joe T.

  9. I have used a snow rake the past 10 winters with great success, but prior to using the snow rake I have had ice dams . The ice dam caused water to leak into my kitchen windows and wall. I cut the legs off of pantyhose and filled the legs with granular salt, tied off the open ends of the leg section and left a 10′ long rope handle. I toss the filled leg a few feet above the edge of the roof. Then I pull the rope handle to position the filled leg perpendicular to gutter to melt a narrow trough for the water to travel off the roof. I also placed a small salt filled leg section on the gutter right above the downspout connection. Thought this worked in an emergency to avoid major damage to the wall and windows. Never miss the show, great content.

    Lee Nuzzo Crown Point, In

  10. We replaced our roof and added insulation in the attic but still get ice dams at the soffits.. There were’nt any baffles so we added some but that hasn’t helped. .I noticed that the lousier have been covered with siding is this the reason? We added a roof ridge when we replaced the roof. HELP!

  11. Lee,
    what type of salt did you use to keep it from freezing? My neighbors have ice shows every winter, and most are elderly, although maybe insulation would help too.

  12. ice dam on roof at bottom of shingles about 4 inches thick and 4 inches wide.. I have removed the gutter and use roof rake to clean the roof off.. but I am still getting water into my bow window.. how can I get this ice off the roof to stop the leak without contacting professional contractor as we are living on social security and have limited it safe to use ice melt ?? when the temp gets to be about 30 degrees that’s when the problems start.. PLEASE HELP.. thank you for your time

  13. This is an absolutely terrific article on ice dams written in layman’s terms. What caught our attention is the focus on PREVENTION. Once you have ice dams it is to late to avoid them. The article also re-enforces our position to avoid electric cables and other melting devices on your roof. Thank you..

  14. I have watched your shows for many many years. Even when your daughter was starting as a single gal on limited shows. Now I can not get your shows since I switch from Dish to Charter tv.
    Questiong: I am 74 and have always lived in stick or brick built homes. We moved from Wisconsin to Florence,Or R. in a 55+ Manufactured
    “Florentine Estates “Gated community. We need info to do home repairs around our homes inside as well as outside. Can you advise or help? We own our homes and our Lots?

  15. Check with your local hardware store for snowmelt which will be safe for use on your roof. It is made especially for roof, most concerns is the salt that is in most of the stuff you pay. Because it can cause roof damage itself at the worse, sometimes even stain your shingles, some home owners have used salt. Placing some in a used nylon stocking and laying it across the worse ice buildup on the roof, cheaper and last longer. Just make sure the salt is safe for your roof, cheap and fast like I said.
    Sometimes you can buy the snowmelt at large retailers like Home Depot,…etc. It does work, but it is only a bandage for a problem with your attic, I have turned off my registers near my worse spot and it helps, along with removing the snow. Like the article says, do it from the ground and be safe.
    Think Spring and God Bless.

  16. We have a ridge vent and soffit vents. There is an hvac unit for the second floor, in the attic which generates heat enough to melt the snow on the roof. How can we isolate this unit from allowing the heat into the attic? Should we put insulation underneath the roof to prevent this? If this unit was not in the attic, I believe we wouldn’t have this problem. It also appears that the venting isn’t adequate.


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