Tis The Season… For Ice Dams!

Many of you are probably not going to agree with me, but I could not be happier with all this snow! Finally, a winter that reminds me of my childhood winters. Growing up in Minneapolis and living here my entire life, I just believe if it’s going to be cold (which ya know it’s going to be!) it might as well be a beautiful winter wonderland! However the ice I could definitely do without and unfortunately, this year we have had a lot of that. Between the ice and snow, we have many homeowners experiencing water damage due to ice dams. The best way to avoid water damage to your home or business due to ice dams is to be aware of what they are and how to prevent.

How Ice Dams Form

A basic explanation of how ice dams form: Snow melts on the roof over the living space of a house if the roof’s temperature is above 32 degrees — often because a house’s heat is leaking up through the attic. The water runs down the roof slope. When reaching the eaves, where the roof extends into below-freezing air, the water freezes into an ice dam. That causes water from additional melting to back up under the shingles. That water can seep into walls and ceilings, causing stains, mold, and mildew.

Other factors in ice dam formation: Snow is an insulator, and just having a thick layer of it on top of the house can cause the roof to get warmer and melt more snow. Freeze-and-melt temperature cycles exacerbate the problem. Complicated roof shapes that include valleys and dormers can keep water backed up on the roof. Homeowners may think that just adding insulation will do the trick, but since insulation doesn’t stop warm air leakage, that’s not enough.

Ice Dam Weather

Ice dams can happen any time you have above-freezing temperatures during the day and below-freezing temperatures at night. Water melts on those warmer days, regardless of the condition of your insulation or your attic temperature.  Much of it will run off your roof during the day, but it’s a slow process. There’s ample time for it to refreeze, which often happens as the sun goes down and the nighttime lows approach.

It doesn’t need to be a downright warm day to cause runoff that leads to ice dams. It can happen with a 33F day and a 29F night. Even a 20-degree day with strong sunshine can melt a lot of snow.

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How To Prevent Ice Dams

The same things that prevent ice dams also help keep heating bills low – tight living spaces with proper insulation and proper attic venting. The combined goal is to keep the attic below freezing so it won’t melt snow sitting on the roof. The heat that escapes into the attic is the enemy here.

Here are some simple steps to find out if your attic is sealed off from heat:

First, test for air leakage by putting a huge fan, or “blower door,” in the front door that sucks the air out of the house. This makes leaks easier to find and measure. Get an auditor to help with this. The auditor can use an infrared scanner or other methods to pick out hot spots in walls and ceilings that indicate where heated air is leaking into the attic.

Next, the auditor evaluates if the house has enough insulation, keeping in mind that building code is a minimum and some houses might need more in order to stave off ice dams.

Finally, the third leg of the stool, consider whether additional venting is needed in the attic to let cold air come in under the roof deck (the wood the shingles are nailed to).

Ice dam victims have to be sure to fix the right thing. If the house isn’t sealed and insulated sufficiently, venting alone is counterproductive, because it can draw more warm air from the house into the attic.

A common misconception is that ice dams are a roof problem. Homeowners may replace their roofs and find to their dismay that nothing’s changed.

Rubber sheathing under the shingles is an extra step to keep water from seeping down to walls and ceilings. This is now a code requirement when a roof is replaced.

Even a tightly sealed, heavily insulated and perfectly vented house may yield to ice dams if deep snow sits on the roof for a long time. Snow acts as insulation, which can cause the snow on the roof to melt. And freeze-and-thaw weather cycles can’t be prevented.

So if there’s lots of snow, homeowners will want to add the low-tech way to prevent ice dams, the snow roof rake. It’s an unwieldy contraption, usually made of aluminum, which allows you to shovel your roof in much the same way you would shovel your driveway. The rakes range from lightweight scrapers to more sophisticated designs using little wheels and chutes.

You can’t have ice dams if there’s nothing on your roof to melt and create them. At the very least, remove the snow if you can, 10 feet from the edge. Let the sun hit the roof, especially in the areas where the ice dams form.

Rake with each snowfall so dams don’t get a chance to get started.

Whatever your strategy, it is not recommended to ever get up on the roof.

Stay safe and warm Minnesota! In the meantime, get your sleds fired up, sounds like we got more snow coming our way! If you have any questions at all about ice dams, please don’t hesitate to call our office. If you should experience water damage due to ice dams or frozen pipes, 24Restore is the only call you will need to make. Our highly trained team is here for you 24 hours a day and 365 days a year. NO job is too big or too small.


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