Ice Dams : How They Form and How to Prevent Them

Icicles hanging along the edges of your gutters may look beautiful, but they spell trouble. That’s because the same conditions that form icicles —snow-covered roofs and freezing weather—also lead to ice dams: thick ridges of solid ice that build up along the eaves of your roof. Ice Dams can tear off gutters, loosen shingles, and cause water to back up and pour into your home. When that happens, it can cause a lot of headaches for homeowners: peeling paint, warped floors, stained and sagging ceilings. Not to mention soggy insulation in the attic, which becomes a magnet for mold and mildew.

How Do I Stop Ice Dams from Forming?

Getting rid of ice dams for good is simple, in principle: Just keep the entire roof the same temperature as the eaves. The process usually begins in your attic space by increasing ventilation, adding insulation, and sealing off every possible air leak that might warm the underside of the roof.

By addressing these common trouble areas, you should enjoy dam-free winters and use less energy to boot:

Ventilate Eaves And Ridge: A ridge vent paired with continuous soffit vents circulates cold air under the entire roof. Both ridge and soffit vents should have the same size openings and provide at least 1 square foot of opening for every 300 square feet of attic floor. Place baffles at the eaves to maintain a clear path for the airflow from the soffit vents.

Cap the Hatch: An unsealed attic hatch or whole-house fan is a massive opening for heat to escape. Cover them with weather-stripped caps made from foil-faced foam board held together with aluminum tape.

Exhaust to the Outside: Make sure that the ducts connected to the kitchen, bathroom, and dryer vents all lead outdoors through either the roof or walls, but never through the soffit.

Add Insulation: More insulation on the attic floor keeps the heat where it belongs. To find how much insulation your attic needs, check with your local building department.

Install Sealed Can Lights: Old-style recessed lights give off great plumes of heat and can’t be insulated without creating a fire hazard. Replace them with sealed “IC” fixtures, which can be covered with insulation.

Flash Around Chimneys: Bridge the gap between chimney and house framing with L-shaped steel flashing held in place with unbroken beads of a fire-stop sealant. Using canned spray foam or insulation isn’t fire safe.

Seal and Insulate Ducts: Spread fiber-reinforced mastic on the joints of HVAC ducts and exhaust ducts. Cover them entirely with R-5 or R-6 foil-faced fiberglass.

Caulk Penetrations: Seal around electrical cables and vent pipes with a fire-stop sealant. Also, look for any spots where light shines up from below or the insulation is stained black by the dirt from passing air.


Keep A-Top Roofing and Construction in mind for all of your roofing needs. We have over 30 years experience and service all parts of Central New Jersey. Our services include: residential and commercial roofing, gutters, skylights, flat and metal roofs, vinyl siding, soffits, facia, replacement doors and windows, decks, porches, columns and mold remediation.

Feel free to give us a call at (732) 446-6341 or find more information about our services on our website: https://a-topconstruction.com/.

A-Top Roofing and Construction is conveniently located at 137 Freehold Road, Manalapan, NJ 07726. We are open daily from 9 AM – 4 PM, five days a week.

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