Ice Dams mostly form at the eve of the roof but can also form above or around anything that obstructs the flow of water like a skylight, chimney, and along a wall. Ice dams can form naturally given certain weather conditions. Many ice dams can be prevented with proper ventilation and having enough insulation in the attic.
Why do ice dams form?
Ice dams form anytime water does not drain off of the roof and out of the gutters. This typically happens when the attic temperature warms up enough to melt the underside layer of snow on the roof. The water travels down to the eve where the temperature is cold enough to freeze. Once ice has formed any additional snow that melts is blocked from exiting the roof and gutter system. Water puddles up behind the ice causing the dam to grow. If the gutter system is not pitched to drain properly or has leaves in the gutter water will not be able to exit the gutters and will form ice in the gutter eventually growing up to the eve of the roof.
Damage caused by ice dams
Once a dam has formed water will seep under the shingles and behind the facia board. Eventually the water will drip into the attic space and exterior walls of the house. Over time the wet roof decking will rot and the insulation can form mildew or mold. When ice expands it can break the seams of the gutter system. Water in the exterior walls can make windows and doors hard to open. Damage can be done to landscaping and walkways around the house. Damage from ice dams can easily cost thousands of dollars to fix and may cause slippery conditions where someone could slip and fall.
How to prevent ice dams from forming
1) Before winter starts make sure that your gutters are free of debris and that all water drains out of the gutter. Standing water in your gutter will form ice in the winter.
2) Have the proper ventilation installed for your home. Ventilation helps equal out the temperature in the attic. In a perfect world having a continuous intake vent along with a continuous exhaust vent is the best form but all houses were not built to achieve today’s standard of proper ventilation. Call a professional to inspect your home to come up with the best scenario for your home.
3) Make sure you have enough insulation in the attic. I recommend having a R49 value. If you are under insulated you will lose heat from your house raising the attic temperature. If you see sections where the snow had melted in spots you can identify where your hot spots are. Adding insulation is a low cost improvement that will actually save you money with heating and cooling cost along with helping to prevent an ice dam.
4) Install a De-Icing cable. De-Icing cables can be installed in the gutter and at the eve of the roof. Installation needs to be done before the winter season. Make sure that the cable runs through the downspout of the gutters to ensure that the downspout does not freeze. Always follow manufactures recommendations for usage.
5) Use a snow rake to remove the snow from the bottom of the roof. Make sure that you only pull the snow in a downward motion. Do not push the rake up the roof. If you pack the snow together an ice dam can form higher up the roof.
Removing an ice dam
Call a professional with experience in removing ice dams. Removing an ice dam requires the use of a ladder in slippery conditions. Ice dams can be broken up with a hammer and calcium chloride to separate the ice from the shingles. Ice dams can also be removed with steam. Caution: Even a trained professional can damage the roof and gutters.
It is better to be proactive than reactive. Focus on the preventive steps so that you can minimize the chance of having an ice dam form. If you have an ice dam you should have it removed as soon as possible to limit the damage done to your home.