Minnesota winter curse: ice dams and attic frost illuminated


Graphic illustration of the anatomy of an ice dam. (Graphic provided by Steve Kuhl, Ice Dam Company)


Steve Kuhl is the founder and owner of the Ice Dam Company and a nationally sought-after expert on ice dams for more than 20 years. A self-described serial entrepreneur, the Ice Dam Company is one of four businesses he has created, all of which relate to construction and design. Officing out of Hopkins, Kuhl helps home and business owners wage on-going battles against ice dams, attic frost, and other challenges that come with maintaining structures in a northern climate. The Ice Dam Company serves all of the Twin Cities, and their website (www.icedamcompany.com) lists their strategies for dealing with some of winter’s worst nemeses.

“There are many things home owners can do to prevent ice dams from forming,” Kuhl said, “which is better than having to pay someone to remove them once they’re there.”

Photo right: A classic ice dam forming on the gutter and eaves. (Photo by Margie O’Loughlin)

1. Have the snow shoveled from your roof, especially if icicles start developing. The cost of doing this a few times each winter isn’t much compared to the cost of dealing with interior water damage. Note that the whole roof surface should be cleared. Removing snow from the bottom couple of feet near the eaves will not keep ice dams from forming and, in some cases, may make ice dams that then form much more severe.

2. Check the attic or rafter spaces for adequate insulation. Proper insulation is one of the best allies in ice dam prevention.

3. Make sure that your roof system has good ventilation. Proper ventilation will allow for the movement of air through the attic and rafter spaces. This reduces the amount of warm air that builds up and reduces the melting snow that causes ice dams.

4. Check that all penetrations through the ceiling are sealed and insulated. Bath fans, plumbing vents, and recessed ceiling cans are some of the biggest culprits that let warm air into the attic. For optimal ice dam prevention, seal and insulate them well.

5. Add heat tape to the lower few feet of roof in areas where ice dams form from year to year. It’s best to address insulation and ventilation first because no amount of heat tape will compensate for the lack of those.

6. Minimize the use of recessed lights in the ceiling below unheated space, such as an attic or a truss cavity. Likewise, avoid turning on recessed lights in exterior soffits. Recessed lights generate a lot of heat, and are seldom insulated or sealed properly. The net result is heat escaping into spaces where it shouldn’t be during the winter.

7. Keep rooms with vaulted ceilings slightly cooler than the rest of the home, especially if these spaces are seldom used.

8. Heat tape, otherwise known as heat cable or roof de-icing cable, is an affordable solution to dealing with ice dams. Be wary of cheap products sold at big box stores. Learn more about quality heat cable products at www.radiantsolutionscompany.com.

Kuhl explained, “This winter hasn’t been that bad for ice dams in Minnesota yet because we just haven’t had that much snow. The classic formula for disaster is heavy snowfall with temperatures fluctuating between zero degrees at night and 20 degrees during the day. That’s what we call the thermal sweet spot. When that happens, I know the phone is going to start ringing off the wall.”

“What we have seen a lot of this year,” Kuhl continued, “is something called attic frost. It’s a lesser known problem, but plenty damaging in its own way. Hot, moist air rises and condenses on the inside of the roof deck, where it freezes on contact. It’s not as catastrophic as ice dams, but the end result is the same. You’ll get cups or quarts of water running down your interior walls when it melts, not the gallons of water you’ll see with ice dams. But it doesn’t take much water to cause a lot of water damage and, sadly, with attic frost, all you can do is let it run its course. It’s also important to know that if you’ve had attic frost, you may have to replace your insulation. Once insulation has gotten wet, it’s compromised and will lose up to 50% of its R-value. When it dries out, it won’t be effective at doing its job anymore.”

Fact or fiction?

Fact: Since winter is far from over, there’s still time to get smart about ice dams and associated problems. While it’s most often the case that heavy snow accumulations create ice dams, they can also occur with relatively little snow on the roof. It’s a question of ice accumulations.

Fiction: Gutters have something to do with ice dams. If your home is prone to ice dams, you’ll get them whether you have gutters or not.

Fact: Gutter systems can be damaged by gutter ice. Fresh water ice weighs about 60 pounds per cubic foot, and gutters are not designed to tolerate that sort of load.

Fiction: When it comes to insulation, the more the better. Over-insulated homes can be just as bad as under-insulated homes when it comes to ice dams; too much insulation can inhibit proper ventilation. If warm air leaks into attic spaces, all the insulation in the world won’t prevent ice dams.

Fact: You can’t always see ice dams from the ground. The sneaky ones above skylights and dormers can be hard to see.

Fiction: Salt socks are a smart way to melt ice dams. People use pantyhose, old socks and store-bought cloth tubes filled with a variety of ice-melting chemicals for removing ice dams. This is not a good idea.

Fact: Ice should be removed by steam; forget the hammers, picks, and hatchets.

Fiction: Ice dams need to be thick to cause problems. A general rule is that the steeper the roof, the thicker the ice dam has to be to cause problems. On lower pitched roofs even a thin ice dam can be problematic.

: The leaking caused by ice dams may not show up right away. By the time you see water inside, it’s usually been there for a while.


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