Ice Dams: Cause and Prevention

Ice dams are a major cause for leaking and interior ceiling damage, as well as large icicles forming from the gutters of roofs.  It is typically a problem on slopped roofs in colder climates. They form when accumulated snow on roofs melt and flow down the roof eventually freezing when temperatures drop during the day or over night. The freezing of the melted snow builds up and extends from the gutters up the roof, eventually finding its way underneath the shingles. As the ice starts to melt again it leaks into the attic and through the ceiling below.

Typical causes of Ice Damming

The melting of snow typically comes from two reasons:

• Inadequate roof/ceiling insulation causing heat to escape through the living space and into the attic melting the standing snow.
• Inadequate ventilation of the attic itself – attics should be as cold as the temperature outside.
• Heating appliances located in the attic can produce heat that might warm up the attic space and roof system.
• Poorly sealed and insulated ductwork can cause heat to escape into the attic space and warm up the roof system.

In addition to the common reasons mentioned above, the snow also can melt on a sunny day causing the melted snow to freeze on cold nights.

Ice Dam Prevention

Ice dams can be avoided by some of the following measures:

• In new construction, ice dams are prevented through building designs with adequate roof insulation and ventilation.
• Snow removal with a roof rake will eliminate the build up of snow and decrease the potential of melting and freezing.
• Building steeper roofs to allow for snow to shed off more easily.
• Ice and water shield (rubber membrane) installed under a new roof can help keep melted water from coming into the home.
• Heat wire run on the perimeter of the roof can help melt the snow before it freezes up the roof line during storms.

For more information on Ice Dams and how they are forming on your home please feel free to contact us.