Seasonal Alert: What Do You Know About Ice Dams?

ice-damsUnfortunately, the season is upon us and as much as we’d love to not deal with the problems of winter, it’s probably a good time to bring up the topic of ice dams.

Here are some common misconceptions about ice dams:


  • They form because of faulty gutters.
  • They are caused by snow melting once the temperature hits the 40s.
  • There’s not much you can do to prevent them.

Drive down most any street in a typical New England winter, and you’ll likely spot homes with icicles lining the gutters. Icicles may look nice, but they often signal the presence of ice dams.


These thick ridges of ice — which build up at the edge of the roof and stop melting snow from draining properly — can cause serious damage, such as:

  • Taking down gutters
  • Loosening shingles
  • Water leaking through the ceiling, windows or walls, leading to soggy insulation,  mold and mildew, warped floors, peeling paint, drooping ceilings and more

Unfortunately, many of the calls we get from both clients and concerned homeowners is only after ice dams have started doing their damage. At Custom Contracting, we recommend taking a long-term view toward ice-dam prevention.

Anatomy of an Ice Dam

As explains, an ice dam is born in three steps:

  1. Heat collects in the attic and warms the roof, except at the eaves.
  2. Snow melts on the warm roof and then freezes on the cold eaves.
  3. Ice accumulates along the eaves, forming a dam. Melt-water from the warm roof backs up behind it, flows under the shingles and into the house.

What conditions are ideal for ice dams to flourish? First, you need snow — even an inch or two is fine. Then the snow melts a bit, because too much heat is escaping from the roof and/or the outdoor temperature has risen enough. Finally, the temperature dips below freezing, the roof cools again and ice dams start to form.

Short-Term Fixes, Long-Term Solutions

If you need to deal with an ice dam right away, there are some short-term fixes you can make. Using tools like hammers, shovels or chisels can damage your roofing, as can sprinkling salt. You’re better off using an extended wheeled roof rake so you can safely remove the snow from the safety of the ground, removing the potential source of water.

But if you’re looking for a long-term solution, you need to improve your insulation. We recommend spray foam insulation, which can be sprayed into the rafters of your house and cuts down dramatically on heat loss. Better attic ventilation complements the insulation by keeping the day-to-day roof temperature more uniform. A cooler roof means slower melting snow, which reduces the occurrence of ice dams.

Like any home maintenance issue, it’s better to be proactive with ice dams than reactive. So be sure to take measures before ice dams have made their mark. And if you have any questions about preventing ice dams, feel free to give us a call.



Custom Contracting, Inc. 1267A Massachusetts Ave. Arlington, MA 02476 Phone: 781-648-2835 Fax: 781-648-0907 Email:

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