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What to Do About Those Damn Ice Dams!

With winter snowfalls just around the corner, we can’t help but remember the power packed storms that rolled through Massachusetts last year. To avoid damage to your home this year, be prepared for one of winter’s major hazards: ice dams. The icicles hanging off the sides of your home may be pretty, but they could spell out disaster.

What is an ice dam?

An ice dam is a frozen water ridge that forms at a roof’s edge preventing melting snow or water from draining off the roof. Ice dams affect gutters and the roof itself, adding pressure and weight that can lead to damage in the walls, ceiling, insulation, and other areas.

How are ice dams caused?

Ice dams form due to leaking heat and warm air from the home below the snow. As the warmth reaches the snow above and causes it to melt, the water runs down the roof and refreezes at the colder edge above the eaves. As this is where gutters are placed, the dam can grow, increasing the chance for damage to the structure.

What kind of damage can ice dams cause?

Left untreated, melted water on the roof of the home expands as it freezes and can back-up underneath shingles. Eventually, the water will drip into the insulation and ceilings before also spreading to exterior walls beneath the eaves ruining sheetrock and paint. If the ice dam becomes too heavy and breaks off the house, it can bring the shingles and gutters it rests on down with it. This can also damage anything underneath should the dam fall on top of it such as shrubs, windowsills, cars, pets, and even people. An ice dam can fall at any time, so they should be considered dangerous and an existing hazard until removed. In addition to structural damage, moist roof sheathing or walls can encourage the growth of mold or begin to even rot. Many of these damages can be costly to repair, so prevention of ice dams is key.

How do you prevent ice dams and damage?

There are many ways to prevent ice dams, ranging from temporary to long term solutions.


  • Heated Cables: Attached with clips along the roof’s edge, this cable is laid in a zigzag pattern and equalizes the roof’s temperature from the outside. This solution is necessary to install before bad weather hits, as it won’t do any good on top of snow or ice.


  • Blow Cold Air: Using a hammer, shovel, or chisel on ice dams could be dangerous not only for the roof below but for you! Throwing ice salt on the dam will cause damage to plants below. Instead, try taking a fan into the attic and aiming it at the part of the roof where water is leaking. The increase in circulated cold air will stop the water and freeze it quickly. The leak can be stopped using this method in a matter of minutes, helping prevent water from spreading further into your home.


  • Rake It: A better alternative to a shovel, a long handled aluminum roof rake can be used from the ground. The removal of the snow or ice can instantly change the temperature of the roof without damaging the shingles or other existing structures.


  • Cap the Hatch: When attic hatches are left unsealed or whole house fans are present that leaves at least two major opportunities for heat to escape. Ideally, you should install weatherstripped caps made from foil-faced foam board held together with aluminum tape.


  • Exhaust the Right Way: Ducts connecting to the kitchen, bathroom, and dryer vents that lead outdoors should be through the roof and walls rather than the soffit vents.


  • Let the Ridge and Eaves Breathe: The ridge vent, located at the top point where the two roof edges meet, helps soffit vents at the base of the roof circulate air throughout. The addition of these vents prevent ice dams from forming. Both ridge and soffit vents should have the same size openings and provide at least 1 square foot of ventilation for every 300 square feet.


  • Utilize Baffles & Insulation: Baffles provide a channel for air to flow through certain points of an attic. This is necessary as even the most well insulated attics require ventilation. More insulation on the attic floor keeps the heat in the home rather than leaking out and creating an environment for ice dams to form. Local professionals will be able to advise how much insulation your specific home needs for the most effective functionality.


  • Flash the Chimney: There can sometimes be a gap between your chimney and the frame of the house. Air can escape here and alter the temperature of the roof, inviting ice dams to form. To prevent this, L-shaped steel flashing can be added. Fire safe sealant should be used as other types of spray foam or insulation could pose hazards for the home.


  • Seal and Insulate Ducts: Paintable fiber-reinforced mastic should be spread on the joints of HVAC ducts and exhaust ducts. Finish off with foil-faced fiberglass covering them completely for optimal insulation.


  • Caulk is Your Friend: Seal around vent pipes or any electric cables with a fire safe sealant. Look specifically for any spots where light shines through as these are clear exits for heat to escape. Areas that have dirt or staining could also be exits to the outside, so these should be considered as well.

What should I do if my house has an ice dam?

It’s no surprise that the sooner you remove the ice dam the better as they can cause serious damage to your home. The best way to remove an ice dam is to allow a professional to steam it away. A steamer uses tap water and heats it to 300 degrees. The steam is then sent through a hose at a low pressure and cuts through the ice without damaging the structure underneath.

Pressure washers are often mistaken for a similar solution, but should not be used to get rid of ice dams. Pressure washers do not heat the water to the most effective temperature, making the process take longer than necessary. They can also damage the roof or gutters.

Another myth is that a common find, the pantyhose, can be filled with ice melting chemicals or salts and slid down the dam in order to melt the ice underneath. This should not be done, since it will not effectively get rid of the dam and possibly damage the roof or plants below. It is safer to contact a steam removal professional for any ice dam needs.

While ice dams can be harmful and pesky, you can end up helping heat stay in your home better when trying to prevent ice dams. This makes your home energy efficient and saves you money. Remember, prevention is key! Check out our Mass Saves Series for more information on how to conserve energy in your home.

Dwell360 is a residential real estate firm based in Newton, Massachusetts, servicing the cities and suburbs of metro Boston. We are focused on our customers and our experience in the residential real estate market is extensive. Search for homes in Massachusetts and then give us a call.

The Ice Dam Company. Removing Ice Dams with Steam: Roof Ice & Gutter Ice Steaming. Retrieved from
Larson, Hendricks, and Huelman, Timothy, Lewis, and Patrick. Ice dams. Retrieved from
Korpella, Robert. How Important is Using Baffles in Attic Insulation?. Retrieved from
Crookshanks, Dennis. (September 24, 2011). Chimney Flashing. Retrieved from
The Editors of This Old House Online. How to Get Rid of Ice Dams. Retrieved from
State Farm. (January 15, 2013). Ice dam [image]. Retrieved from