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Finding an Ice Dam on a Home Inspection

Finding ice dams on a Home Inspection?

If you live in a cold, snowy climate you are familiar with ice dams. An ice dam is a wall of ice that forms at the edge of a roof (usually the gutters or soffit) and prevents melting snow (water) from draining off the roof.

What causes ice dams?

Three things are required for an ice dam to form: snow, heat to melt the snow and cold to refreeze the melted snow into solid ice. Ice dams can form when as little as 1 or 2 inches of snow accumulates on a roof – if the roof is poorly insulated and air sealed, and the snowfall is followed by several days of sub-freezing temperatures. Warm air inside your home leaks into the attic and will warm the underside of the roof causing snow and ice on the roof to melt. The melted snow (water) will drain along the roof, under the snow, until it reaches the cold overhang. The overhang tends to be at the same temperature as the outdoors and the melted water will refreeze and form an ice dam and icicles.

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 are on the average below 32°F. So the water above backs up behind the ice dam and remains a liquid. The water that backs up behind the dam gets trapped and works its way back up the roof, getting under shingles and can leak into the home causing damage to walls, ceilings, insulation, and other areas.

Immediate action:

  • Recommend that the seller remove snow from the roof. This eliminates one of the key ingredients necessary for the formation of an ice dam. A "roof rake" and push broom (which can be purchased at your local DIY store) can be used to remove snow, but be careful as it is possible to damage the roofing materials.
  • You want to make sure that your client is informed about the dams you encounter and what they can potentially expect to see on their home in the spring when the snow melts.

 

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