Ice Dam Causes and Solutions
What causes ice dams?
The two main causes of ice dams are lack of ventilation and insufficient insulation in a home’s attic. During the winter, the ideal temperature inside the attic should be the same as the outside air. For instance, if it is 15 degrees outside then it should be 15 degrees inside the attic. If not, the home is most likely experiencing “heat in the attic”. This happens because the heat inside the home is “escaping” up through the ceiling, past the attic insulation and into the attic space. Since the air inside the attic is now warmer than the outside air, the snow on the roof begins to melt. This melted snow in turn begins to flow down the roof until it reaches the overhang. Whether or not the home has gutters does not matter. The cold air space under the eaves (soffit) will cause the melted water to immediately freeze, forming icicles and eventually ice dams. (This is also the same concept that causes bridges to freeze before the rest of the road). The danger is caused not only by the weight of ice hanging off the roof or building up inside the gutters. As this process continues, the melted water begins to be trapped behind the ice dam and has nowhere to go. Eventually this “blocked” water works its way under the shingles and back into the attic causing damage to the roof decking, insulation and eventually to the interior ceilings.
This graphic shows how heat escaping from the home into the attic space causes the snow to melt and then re-freeze at the overhang causing an ice dam and then trapped water to leak back into the attic and ceilings.
How to eliminate ice dams?
There are several ways to fix the problem in a traditional attic. The most cost effective is to upgrade your home’s level and type of insulation to cellulose. Most homes are under-insulated with a few inches of blown or batted fiberglass which is a very porous material. Whereas Cellulose is a much more dense product and does a better job to cut off the heat trying to escape from inside the home. It’s estimated that investing in the right form of insulation can pay the homeowner back in about 3 years. In conjunction with adding the right amount of insulation (Department of Energy recommends an R-60 for Michigan) you also need to make sure that the home is properly ventilated. This may require pulling back the existing insulation and adding baffles to at least every other rafter as well as making sure the intake and exhaust ventilation is sufficient. In cases where a home does not have a traditional overhang and soffit to be ventilated, a solar powered intake booster may be used as a “by-pass”. With all this being said, sometimes due to the way a sun hits a home, prevailing winds or simply the design of the home such as cathedral ceilings it is not possible to fix ice dams through traditional means. For these unusual situations we recommend installing Helmet Heat. If you would like to have a professional evaluation of your home’s roof or attic system, give us a call today!
