A favorite scene in A Christmas Story is when little Ralphie concocts a story that an icicle fell and struck him, injuring his eye, all in an attempt to cover the misfortunes of an errant BB. In Christmas Vacation, Clark Griswold was in the process of hanging 25,000 imported Italian twinkle lights when he fell off the ladder and grabbed the house gutter, causing a 4-foot ice missile to launch out of the gutter, through his neighbor’s window and into his expensive stereo system. The moral of both these tales is that ice can be dangerous not only to little kids with Red Ryder BB guns but also to neighbors with expensive audio equipment. But did you know that ice can also be dangerous to your home?
Ice dams form when snow accumulates on the slanted roof of your house and the warmer attic air melts the snow over the living space of your home but does not melt snow and ice that exist on your roof overhang. The melting snow and ice run down your eaves and into the gutters. This pattern of snow melt and refreezing continues to the point where your gutter cannot hold any more thawed snow and begins to back up and pool under your roof covering, leaking into your attic and along the exterior walls of your home. This water can cause damage to exterior walls requiring replacement of insulation, drywall or plaster and wall coverings. If the damage takes place repeatedly or over a long period of time, your wall framing can rot and mold can develop.
Preventing ice dams
- Ensure adequate insulation in the attic to eliminate heat buildup in the space below your roof.
- Seal any openings that allow heated air to bypass insulation and enter into the attic.
- Improve ventilation which will cool the attic space and remove unwanted moisture.
- Keep the attic air temperature below freezing when outside air is also below freezing.
- Do not install large mechanical equipment such as furnaces or water heaters in attics as they can significantly raise attic temperatures and speed up melting of roof snow.
- Make sure ice and water shield membranes are installed on your roof the next time it is replaced to prevent melting snow from getting under your roof decking. (Most building codes now require use of ice and water shields in cold weather climates.)
What not to do if you have an ice dam
- Do not attempt to remove the snow from the roof or chip away at the ice buildup. This may lead to shingle damage. If you wish to have snow or ice removed to prevent additional ice damming damage, please contact a professional.
- Do not attempt to get on the roof to clear the ice dam or remove snow due to the potential for slipping and falling.
- Do not use salt or snow melting chemicals to melt snow on the roof. These chemicals are corrosive and can shorten the life of metal gutters, downspouts, flashing, and damage nearby landscaping plants and grass.
And you thought ice was only dangerous to eyes, audio equipment, hips and cars! We can now add our homes to that list. I hope you found this information helpful in understanding how ice dams form and what can be done to prevent them and the damage they can cause. If you have ever had to deal with an ice dam, I would love to hear your experience.