The Role of Insulation and Air Sealing in Preventing Ice Dams
Do you see icicles dangling from your home’s roof or gutters? This could be a sign of a potentially costly problem. If you live in an area that experiences significant snowfall and cold temperatures, your home is a candidate for forming ice dams.
What exactly is an ice dam and why is it a problem?
An ice dam is formed from water that has accumulated at the edge of the roof. It is a problem for three reasons:
- If the ice dam forms on the eaves, it will impede ventilation of the attic.
- The ice dam can stop water from draining away, and if unfrozen, the water can cause mould, water leaks in the ceiling, or larger ice dams.
- In the spring, any ice in the attic will melt and potentially cause water damage, including dripping through the ceiling into the home
Water leaking into the home can be a costly problem. Aviva Canada, one of the country’s leading property and casualty insurance groups, estimates that the average homeowner claim for water damage is $16,070. Worse still, this seems to be a growing problem. Aviva Canada also reports that claims resulting from water damage have increased in recent years, from 39% of total dollars paid out in 2004 to 44% in 2014.
Why do I get ice dams?
There are three potential causes of ice dams:
- Insufficient attic ventilation—the eaves must be free to allow air in, and there must be sufficient exhaust vents high up on the roof.
- Faulty air sealing—this will let moist, warm air from the house rise into the attic.
- Insufficient and/or uneven attic insulation—this will lead to snow melting from the roof.
Is it more cost effective to prevent ice dams or to remediate the damage?
Spending the time and money to prevent ice dams is much easier, and more economical, than trying to fix them once they form. Calling a roofing crew to remove ice and snow is costly and more expensive than having an insulation professional seal and insulate for you. Plus, you run the risk of roof damage during the removal process, and ice removal won’t stop ice dams from forming again. Insulation and air sealing are much more reliable and permanent ice dam solutions.
My house gets ice dams. What should I do?
Sometimes space is limited as the roof slopes and meets the wall, so people fail to install the proper amount of insulation in these areas. However, it is exactly this area where the damming occurs, so it is especially important to make sure you have both sealed and insulated it fully—without putting insulation on the eaves.
If you believe your home is a candidate for ice dams or you’ve had them before, you need to air seal and correct insulation before winter sets in. You can do the job yourself or hire an insulation professional to ensure it is done right. Either way, pay special attention to ensuring the roof insulation is installed properly where the roof meets the wall. Ice dam solutions for a given home may not be limited to air sealing and insulation, but it is a necessary component.
Make sure your insulation is correctly installed.
Improper installation can lead to air leaks and issues—like ice dams. Whether you DIY or hire a pro, make sure you’re following the proper procedures when installing insulation.
For more information on high performing building envelopes and expert tips on how to install insulation, visit NAIMA Canada.
North American Insulation Manufacturers Association (NAIMA) Canada promotes energy efficiency and environmental preservation through the use of fibre glass, rock wool, and slag wool insulation, and encourages the safe production and use of these materials.