What is an Ice Dam?

Every year, we in New England, see strange weather patterns in the winter months and this week has proven this true. The bomb cyclone last week (who even knew that was a thing) followed by single digit days with sub-zero temps at night and now temps expected in the high 50’s with rain. Some would say what’s next. And we can tell you- ice dams. The uneven melting and freezing of snow.


They seem to be an inevitable part of New England winters with the freezing and thawing of the snow accumulation on rooftops. From Newton to Sherborn, you can see the icicles forming along the eaves.The question is- why do we all seem complacent leaving this phenomenon to chance when there are ways to try and prevent ice dams? Not to mention the aftermath of the large insurance claims and inconvenience in the middle of winter of repairing the damage caused.


To explain the science behind ice dams to the layman is challenging, but the past Head of the Department of Environmental Conservation and the Building and Construction Technology program at the UMass, Amherst does a pretty good job- save for the paragraphs on snow’s R-value; read the full article here.  


The article is a comprehensive look at the interior and exterior forces that contribute to ice dams forming. Below are three takeaways to consider:


  • The cause of ice dams form by the heat lost from the house. “Develop a strategy that is centered around this fact whenever possible. Ventilate, insulate well and block as many air leaks as practical. There are no excuses for new construction. However, cures for existing structures are often elusive and expensive. In some cases you have to treat the symptom. The payback is damage prevented.”

  • “It is a vicious cycle. The more heat lost – the more ice dams form – the more it leaks – the more the insulation gets damaged – and so on.”

  • It is recommended that “carefully removing snow from roofs with roof snow rakes does help. You can scrape some of the protective mineral surface from asphalt shingles as you remove snow, but removing the insulating snow and potential meltwater does help reduce ice dam potential – just be careful.”


And what is the surprise takeaway? Contrary to popular belief, gutters do not cause ice dams. If you cannot do the snow removal yourself we suggest getting in touch with a local landscaping company to help with raking your roofs because they won’t be mowing your lawn for a while!


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