What is an Ice Dam?

An ice dam is a ridge of ice that forms at the edge of a roof and prevents melting snow (water) from draining off the roof. The water that backs up behind the dam can leak into a home and cause damage to walls, ceilings, insulation and other areas.

Effects of ice dams

 

If the snowfall has been heavy, or a large amount of ice has accumulated, the amount of water that enters the home can be significant enough to cause major drywall damage. If the drywall begins to bubble and turn yellow, most likely this drywall will need to be removed.

Moisture entering the home from ice dams can lead to the growth of mold and mildew. These can cause respiratory problems.

  • Prevent the growth of mold and mildew by immediately drying out portions of the house that are wet or damp.
  • Take immediate action to get rid of the water source, clean the home environment and maintain its air quality.
(Credit; This Old House)

What causes ice dams?

 

 

 

 

 

 

 

Nonuniform roof surface temperatures lead to ice dams.

Heat loss from a house, snow cover and outside temperatures interact to form ice dams. For ice dams to form there must be snow on the roof and, at the same time, higher portions of the roof’s outside surface must be above 32 degrees F (freezing) while lower surfaces are below 32F. These are average temperatures over sustained periods of time. For a portion of the roof to be below freezing, outside temperatures must also be below freezing.

The snow on a roof surface that is above freezing will melt. As water flows down the roof it reaches the portion of the roof that is below 32F and freezes. This causes the ice dam.

The dam grows as it is fed by the melting snow above it, but it will limit itself to the portions of the roof that average below 32F. So the water above backs up behind the ice dam and remains a liquid. This water finds cracks and openings in the exterior roof covering and flows into the attic space. From the attic it could flow into exterior walls or through the ceiling insulation and stain the ceiling finish.

(Credit; This Old House)

How to Get Rid of Ice Dams Fast

Use a snow rake. After a heavy snowfall, give your roof a break by raking the snow off. This inexpensive tool pulls down the snow so it can’t melt and then refreeze into an ice dam. Only use a snow rake from the ground or your deck, never from a ladder. And be careful not to break shingles, which can be brittle in bitter cold temperatures.

Try calcium chloride. Avoid using rock salt as it can damage paint and metal on your home. But calcium chloride can help melt ice and get water flowing again.

Install heat cables. Mount heat cables along the edge of your roof and through the downspout so snow melts and runs down the proper channels.

Steam it off. If you have an ice dam already and you can see that there is a leak coming into your home, you’ll want to remedy it as soon as possible. Check with local roofing companies to see if they have a steamer that can melt the ice off the roof without damaging your shingles. If it’s too big a job for just you, hire a roofing professional to steam off ice dams.

(Credit: American Family Insurance)