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3 Common Causes of Ice Dams

Ice Dam on Roof
Snow poses a lot of potential problems for those who live in cold climates. One common source of trouble involves the formation on a roof. Ice dams happen when snow on the roof partially melts and then refreezes at the edge of the roof, creating dams that allow water to pool up behind them. Unless dealt with, ice dams often lead to leaks and roof rot.
Unfortunately, many homeowners fail to understand the factors that give rise to ice dams. As a result, they mistakenly assume that they can't do anything to prevent these problematic facets of wintertime life. This article seeks to dispel this incorrect assumption by discussing three of the factors that contribute to the formation of ice dams.

1. Uneven Insulation

Ice dams happen when snow on different parts of your roof melts at different rates. More specifically, the issue arises when the roof over your attic has a higher temperature than the roof located along your eaves. As snow on the main part of your roof melts and runs downward, it refreezes when it reaches the relatively colder eaves.
This unwanted temperature disparity often stems from insufficiently insulated portions of your attic. In such places, warm air rising up into your attic passes through the roof and causes snow to melt at an accelerated rate. The solution involves insulating your entire attic evenly - and adequately.
Manufacturers rate insulation in terms of R-value, with higher R-values indicating a greater insulating ability. The US Department of Energy recommends insulating roofs to a value of R-38. However, this R-value may not be high enough to prevent ice dams in cold-prone states like Minnesota. There homeowners can best prevent ice dams by insulating to an R-value of 60.

2. Poor Ventilation

No matter how well insulated your attic, some heat will naturally escape upward from your home. To keep this heat from causing unwanted snow melt, your roof must be properly vented. In other words, outside air must be able to easily flow beneath and through your roof. Such airflow helps to keep the roof temperature within acceptable means.
For this reason, almost all roofs contain special ridge vents meant to promote airflow. Yet over time, these vents often become clogged by dust, debris, and animal nests. As a result, warm air remains trapped beneath your roof, greatly increasing the likelihood of ice dams forming. Therefore, you should have your ridge vents periodically inspected and cleaned to ensure optimal air flow.
Be aware, however, that ventilation alone may not be enough to prevent ice dams from forming. An under insulated attic may allow enough heat to reach your roof to cause snow melt - even if your vents have no obstructions whatsoever.

3. Temperature Fluctuations

Ice dams don't always stem from causes that you can control. Even on a perfectly ventilated and insulated roof, ice dams may form as the result of temperatures that fluctuate back and forth across the freezing point. If the temperature climbs just above freezing during the day, some of the snow on your roof naturally softens and melts.
Once night rolls around, the temperature often drops back below freezing. As a result, any half-melted snow that has slumped down toward your eaves freezes once again. This process often causes ice to form along the edges of your roof. Fortunately, provided you have addressed both of the issues above, temperature fluctuations alone shouldn't create very serious ice dams.
If you have noticed that snow and ice have begun to accumulate along your eaves, use a rake to carefully break up and hills or ridges that have formed. If the problem seems to recur frequently, seek professional help. For more information about what it takes to keep ice dams at bay, please contact the experts at Spray Foam Tech LLC.