Ice dam beginning to form on the roof of a house

What is an Ice Dam?

Ice dams are the result of heat escaping your home through the attic or ceiling and melting the snow on your roof. This causes water to run down your roof and to then eventually re-freeze at the edge of your roof where it is colder. As this ice builds-up, it causes an “ice dam” which blocks any additional water from being able to drain off of your roof.

Why Are Ice Dams Dangerous?

When the water that would ordinarily run off of your roof becomes trapped behind an ice dam, that pooled-up water begins to back up on the roof as it collects, freezes and expands, causing it to force its way under your roof's shingles. As the process of freezing and thawing continues throughout the warmth of winter days and the cold of winter nights, water is eventually forced into the attic or down onto ceilings and inside walls often causing extensive water damage. In addition to the damage that is caused to your roof and its underlying support structure, ice dams can also lead to rotting wood, moldy insulation, destroyed drywall, electrical damage and stained or ruined carpets. 

How to Prevent Ice Dams

Inspect your Homes Insulation & Stop Air Leaks

Insufficient insulation and air leaks are the primary reason for the formation of ice dams. The best way to prevent ice dams is to maintain a cold roof. Use sufficient insulation in the attic to keep the inside warm air from getting into the attic and warming the roof. Building codes require 12-14” inches of fiberglass or cellulose insulation in the attic, so homeowners should check the depth of insulation in their home. Ensure that any cut-out areas around pipes, vents and ceiling fixtures are sealed with foam or caulk to prevent air leaks. Maintaining a cool, well-ventilated attic space that will not allow the roof to warm up is also a good way to prevent the formation of ice dams. 

Remove the Snow from your Roof

Perhaps the most effective way to prevent the formation of ice dams is to remove any accumulation after each heavy snowfall. If your home has a low-sloped roof, a heavy duty broom can be used to push the snow off your roof. If your house has a steep slope, you might want to use a roof rake instead (which is a scraper designed specifically to remove snow from your rooftop). 

Consider Installing a Metal Roof in the Future

While an update like this might not initially be in the home-improvement budget, installing a metal roof on a home in an area prone to heavy snowfall could save you money and hassle in the long term. While ice can still form on a metal roof, the material will not allow water to penetrate into your home, protecting your insulation and ceiling from rot and mold.


 Sources of heat leakage into the attic that should be addressed include the following:
 »  Ceiling light fixtures.
 »  All plumbing and heating penetrations.
 »  Attic hatches and pull-down stairs.
 »  Dropped ceilings over bathtubs, closets and cabinets, and kitchen soffits.
 »  Where walls aren't completely sealed (attic stairways, interior partition walls, etc).
 »  Electrical and phone cables, electrical boxes and fan housings, such as exhaust fans.
 »  Skylights.

 What to do if you get an ice dam:
 »  If you see water staining a wall or ceiling where there is snow on the roof above it, act quickly to avoid extensive damage.
 »  Hire a contractor to carefully remove most of the snow from the roof above the ice dam.
 »  Have the contractor create one or two grooves in the ice dam to allow the pooling water behind the ice dam to drain off. These grooves should go down to the actual roofing as damage to the roof may occur. If required, the contractor can use heat tape in the groove on a temporary basis to keep the groove from re-freezing closed.
 »  Do not chop or chip away the ice of an ice dam, as the roof shingles can be damaged.
 »  Do not use salt or calcium chloride to melt snow on a roof, as these chemicals are very corrosive.

Take preventative measures to ensure that your home's infrastructure is protected from ice dams- which will protect the investment you've made in your home, as well as your family's safety, security and peace of mind.




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