Q: As the temperature drops this week, I’m starting to think about potential winter storms that could head our way. I’m wondering what my options are to help prevent ice dams from forming on my roof. Any suggestions?

 A: New England’s weather is unpredictable, and it’s hard to say when the first winter winds will blow our way. Many homeowners ask us how to prevent ice dams, since their presence can result in significant damage to both the inside and outside of a home. Here is our best advice on how to prevent ice dams:

How do Ice Dams Form?

To properly protect your home from ice dams, it helps to understand how they form in the first place. Ice dams are primarily a result of heat loss in your home.  In other words, if your attic and roof are poorly insulated and ventilated, your attic and roof will heat up and melt snow or ice that has collected on your roof.

When this snow on your roof melts, it trickles down and refreezes back into ice, typically at your home’s soffit (the underside of your eaves) or by the gutters where heat isn’t collecting and freezing temperatures remain. It’s at this point that ice begins to build up and an ice dam forms at the edge of your roof.

Preventing Ice Dams with Proper Attic Insulation and Ventilation

In order to prevent ice dams, your attic should be properly ventilated and insulated. Essentially, your attic should be the same temperature as the outdoors. According to House Logic, the most efficient attic insulation option is closed-cell polyurethane foam. This is a spray foam insulation with a rated R-Value of 6.0 to 6.5 per square inch. The downside is that this option is relatively expensive compared to its fiberglass counterpart, which is the most popular attic insulation.

Unfortunately, fiberglass batting insulation is roughly half the R-value of closed-cell polyurethane foam. Fiberglass insulation has a rated R-Value of 3-4 per inch, which translates to an R-13 for a 2’x4’ framed wall. This can help prevent ice dams as well, but it may not be as effective as the spray foam option. On the flipside, fiberglass is easy to install while spray foam requires professional installation.

Increase Air Flow in Your Attic to Reduce Ice Dams

Wait, why would you want cold air flowing through your attic in the wintertime? While this may sound counterproductive, the truth is that you need maximized air ventilation to reduce the likelihood of ice dams. The minimum ventilation flow should be 1 sq. foot for 300 sq. feet of ceiling space. If you plan to add soffit vents, it’s generally best to install an 8”x16” vent in every other rafter space, which ensures that your home is receiving the best airflow possible.

Ridge vents are another way to help prevent ice dams. This is an exterior component that will circulate cold air under the roof. In addition, it’s important to have 6 feet of leak barrier protection around all valley, eave, and rake edges. In the event that water does seep through your shingles, leak barrier protection will prevent this water from penetrating through the under layers of your roof.

Plug up Those Air Leaks

Your roof and attic can lose up to 25% of your home’s energy. According to Energy Star, energy escape routes near your roof and attic include recessed lighting, dropped soffit, and the duct register. You can also lose energy from areas such as plumbing pipes and chimneys.

Sealing attic leaks can be tricky, but not impossible. For small holes around pipes, you can stuff a small piece of fiberglass batting insulation around the space and fill it with spray foam insulation. You can also seal plumbing vents and electrical wires with expanding foam, but be sure to contact an insulation professional if you’re weary about proceeding.

A Quality Roofing System that Will Stand the Test of Time

A quality roofing system is key to helping prevent ice dams this winter. If you’ve had issues with ice dams in the past or you’re concerned about them forming on your roof this winter, Coastal Windows & Exteriors can help. Contact us with questions at 978-304-0495 or by e-mailing questions@mycoastalwindows.com. We’re ready to help protect your home this winter.