Taming Ice Dams
Ice dams are a serious winter time problem that cause millions of dollars worth of damage each and every year. In simple terms an ice dam causes water to run underneath your shingles and into your house necessitating repair to your roof and potentially causing water damage to ceilings, walls and floors.
The Cause - Heat in the attic raises the temperature of the roof sheathing enough to melt snow that is resting on the roof. Water then runs down the roof until it reaches the eaves where it is cooler and refreezes creating a "dam". As snow continues to melt and and refreeze at the dam water is forced back up under the shingles and many times right into the house.
What Not To Do - Don't go up on your roof with a sharp instrument! Your roof will be very slippery and hacking at the ice is likely to harm you, the roof or both. Additionally, do not stand on the ground and try to chip the ice away as snow or ice may slide off the roof on top of you.
Temporary Fix - What can you do if you have an ice dam on your roof? Calling a roofing contractor with ice dam experience to take care of the problem is a good idea. But if a contractor is not readily available take a pair of panty hose and fill one leg with calcium chloride ice melter. Place the hose so that it is in contact with the ice dam and hangs down to (and slightly over) the edge of your roof. The calcium chloride will melt the ice dam over time and create a channel through which water may begin to drain off the roof. Note, this can help you avoid more serious damage from an ice dam but is only a temporary fix. You will need to address this problem when weather allows or risk more damage in the future.
What About The Damage? - Once the immediate concern of leaking water is taken care of you should plan to get estimates from 2-3 licensed roofing contractors to repair the damage. Ice dams can cause significant damage to your roof and it is imperative that it is repaired correctly or you may find yourself back at square one the next heavy rain or snowfall.
Long Term Fix - There are a number of solutions out there (such as heated cables, heated tape, etc) that offer iffy results, and may actually reduce the life of your shingles. To really solve the problem of ice dams you must address the issue of heat in your attic. Keeping your attic's temperature near to the outside temperature means snow on the roof will not melt, thus no ice dam. How do you keep your attic temperature where it should be? Keep reading.
Insulation - Insulating your attic will help keep the heat from your house where you want it - in the house. Keeping your roof at a low enough temperature keep ice dams from forming is an added benefit. Just because your attic has insulation now doesn't mean it has enough. If you are in the northern United States or Canada (where the majority of ice dam problems are seen) we recommend at least R-38 (roughly a foot of fiberglass insulation) for your attic.
Ventilation - Installing a ridge and soffit ventilation system will also help in maintaining your roofs cool. Air enters vents located at the bottom of the roof (in the soffits) and travels up the sheathing of the roof to the vented ridge cap. The continuously venting air quickly takes heat out of the attic and cools the roof sheathing as it flows up to the ridge cap making it a very efficient system.
Air Leaks - Check around bathroom and kitchen vents to make sure they do not allow air into the attic. Your attic access is also a prime location for warm air to escape. Seal all air leaks with foam or chalking and make sure your attic access is as insulated as possible.