Sometimes, homes are particularly ice dam prone. Sometimes, it’s because the homeowners have terrible luck.
More often, there are simply some design flaws in the home or poorly installed systems in the home which are causing problems. Here are two “secret enemies” that could be creating problems on your roof.
Exhaust fans are an important part of your home’s moisture removal system. They prevent mold, mildew, and excess humidity by drawing shower vapor and cooking steam up and out of kitchens and bathrooms. You should have a fan in each bathroom, as well as possibly one under the vent hood of your stove.
However, these allies can become enemies if they’ve been installed improperly. These exhaust fans are supposed to vent outside of your home. They should be outfitted with ventilation hoods and then sealed with flashing and caulking to ensure that the air goes where it’s supposed to go (outside, and not into the attic space!) without creating any leaks.
Often, however, builders do not understand the problem with venting all of this hot air directly into the attic. The vent pipes stop there, and don’t actually exit the roof.
Most of what exhaust fans vent is hot air and moisture. When you run the fan you are forcing the hot air through the exhaust pipe. If the pipe exhaust flows into your attic you are now filling your attic with extra heat. This means that your roof will tend to get hot, which means ice dams will tend to form. Any snow on your roof will melt on the hot portions of your roof, only to re-freeze when it makes its way to the colder overhangs.
If your home is especially prone to ice dams it’s a good idea to check your attic. If you’ve got three bathrooms and three vent pipes exhausting straight into your attic, then you’ve essentially got yourself an ice dam factory. Call a contractor as soon as you can to get those exhaust pipes vented outside of your home.
Heater ducts are not really supposed to run, uninsulated, straight through the attic. Yet it happens all the time. It’s a cheap, easy way for builders to get the heater installed. Check out this video from a home energy company to see what it looks like:
Again, head up to the attic and have a look. If you see an uninsulated heat duct, then you need to get those HVAC lines insulated with the proper layer of insulation right away. Otherwise, you are essentially heating your attic with 70-degree non-insulated pipes every single day (warming your attic space and roof deck), which all but guarantees that you will get trapped in the cycle of melting and re-freezing snow that forms ice dams.
Remember, hot attics are the enemy!
Hot attics probably cause anywhere from 70% to 80% of the ice dams that form each winter. As a homeowner, your goal should be to keep your attic as close to the outside temperature as possible, even as you enjoy toasty warmth in the living areas of your home.
There’s no substitute for a home energy audit that addresses all of the issues which may be allowing heat to escape from your living space into your attic. However, addressing HVAC lines and exhaust vents may nevertheless help you drop the temperature in your attic rather dramatically, reducing the amount of money you have to spend on ice dam removal every year (not to mention your heating bill).