Be Prepared This Winter
The same force that causes hot air balloons to rise can create conditions in the home that are favorable for ice dam formation. Ice dams are actually caused by the presence of warm air in the attic, combined with snow on the roof and the right weather conditions.
What is an Ice Dam?
An ice dam is a ridge of ice that forms at the edge of the roof and prevents melting snow from draining off the roof. Warm air leaking from the house into the attic is the primary cause of ice dams. When heat leaks into the attic it melts the underside of the snow on the roof, which then flows down the roof surface until it reaches a cold spot (such as the eaves or soffit) where it forms a frozen dam. The ice build-up can back up under the shingles, damaging them and allowing water to leak to the ceilings and walls below.
How Do Ice Dams Form?
Ice dams form when melted snow refreezes at roof edges. Anyone who has lived in cold climates has seen ice dams. We’ve enjoyed the sparkling beauty of ice formations built along roof eaves (of other people’s homes). However, most of us don’t stop to understand why these ice bands form until they damage our own home.
- Indoor heating rises through the ceiling into the attic and warms the roof surface
- Snow on the heated part of the roof melts and flows down until it reaches that part of the roof that is below 32 degrees. Water freezes into an ice dam.
- The dam grows as it is fed by melting snow above, but water held by the dam backs up and stays liquid.
- Eventually, the water finds cracks in the roof covering and flows into the attic from where it could seep through the ceiling and interior walls.
Click here to learn more about Ice Dam prevention.