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Preventing and removing ice dams

Updated: Jan 20, 2021

Ice dams, the ridge of ice which can build up on roof eaves, are a common problem in climates with harsh winters. An ice dam has the potential to cause serious damage to both a roof and the inside of your building. It is important to take steps to help protect your building from the risks associated with ice dams.

What is an ice dam?

An ice dam can form when water from melting snow re-freezes at the edge of your roofline. Without roof snow removal the ice dam may grow large enough to prevent water from draining off the roof. The water can then back up underneath the roof shingles and make its way inside the building.

Immediate steps you can take:

  • Remove snow from your roof after every storm. Use a roof rake to clear the first three to four feet of snow from your roof immediately after each winter storm to prevent ice dams from forming. While the amount of snow and ice that your roof can handle may vary depending on a number of factors such as the roof type, age and condition of the structure, a good rule of thumb is if there is more than a foot of heavy, wet snow and ice on your roof, you should try to have it removed.

  • Clear downspouts. An easy way to help snow and ice drain off your roof is to make sure the area around your downspouts is clear. This will make it possible for your gutters to drain when snow does melt. It will also help prevent flooding when the snow and ice melts.

Long-term prevention:

Ultimately, the best prevention for ice dams is to eliminate the conditions that make it possible for them to form in the first place.

  • Insulate your attic spaces. Make sure your attic is well insulated to help prevent the melting-and-freezing cycle that causes ice dams to form. Check and seal places where warm air could leak from your main building to the attic including vent pipes, exhaust fans, chimneys, attic hatches and light fixtures.

  • Install a water-repellant membrane. When replacing a roof, make sure to install a water membrane underneath the shingles. This will act as an extra barrier that helps prevent water from seeping inside a building.

Flat or low sloped roofs

Flat or low-sloped roofs, which are common in commercial buildings, can be particularly vulnerable to water leaks. Often an ice dam prevents water from flowing into roof drains, which makes the roof susceptible to leaks. Some things to consider in this scenario:

  • Snow removal: if you can reach the roof safely, removing snow can prevent an ice dam. A heavy duty push broom with stiff brittles may be used to brush off the snow on low-sloped or flat roofs. Avoid shovels and snow blowers as they may tear up the existing roof cover system.

  • Heating cables: Heating cables can be installed to prevent ice build-up in key locations such as gutters, near drains or strategically to facilitate drainage.

  • Dry inspection: When your roof is dry, inspect the roof cover for evidence of long-term standing water. Evidence of such a problem can include: mold, mildew or even small vegetation. Such issues are likely caused by a problem with the slope of the roof cover system. A roof cover system can likely be re-pitched by a roofing contractor.

Removing ice dams

Just because an ice dam is present does not necessarily mean water has penetrated the roof membrane. However, it is always best to remove ice dams before they have the opportunity to cause damage. To determine if you have damage, look for water stains or moisture in the attic or around the tops of exterior walls on the top floor.

  • Removal of dam: If you can reach the roof safely, try to knock the ice dam off with a roof rake or cut a channel through the ice to allow standing water to drain. However it is not recommended to try chipping or breaking ice dams due to the damage that can be inflicted on the roof.

  • Be safe: If you cannot reach the roof safely, consider hiring a professional contractor to remove it.

  • Ice melt: Another method is to fill a nylon stocking with calcium chloride ice melt and place it vertically across the ice dam so that it melts a channel through the dam. If you try this method, make sure you can safely position the ice melt on your roof, and make sure to use calcium chloride, not rock salt. Rock salt will damage your roof. Also be aware that shrubbery and plantings near the gutter or downspout may be damaged.

An ice dam can lead to damage to buildings. Preventing an ice dam involves smart planning and regular maintenance during the winter months. If you do not have the manpower to handle regular maintenance or cannot safely reach your roof, consider hiring a professional contractor to avoid the costly repair expense.

You can learn more about insulation, soffit vents, ridge vents, or shingle underlayment by reaching out to us at Nelson-Young Lumber!


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1 Comment

Alison Cooper
Alison Cooper
Jul 22, 2023

When installing or repairing your roof, consider using an ice and water shield underlayment. This waterproofing material helps prevent water penetration and ice dams. Always choose Roof Repair Miramar experts because they have skilled staff, who have the capability to deal with all types of roof issues.

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