Ice dam formation is the result of continuous freezing and thawing of snow due to escaping heat from the house or from gutters being backed up with frozen slush. When this occurs, water may be driven under the roof which may cause ceiling, wall, insulation and gutter dam ventilating the attic. To help with water intrusion into your home, make sure you have six ft. of ice and water barrier under your roof shingles (measuring from the gutter line up.) Try to keep the edges clear with a snow rake. Install electric elements to help melt snow and ice on high roofs. Ice dams can be prevented from forming by: Installing a vapor barrier above the home’s warm space, insulating the attic floor and ventilating the attic.If water has found it’s way into your attic, you will probably see mold starting to grow along the lower edges of the roof. Do not let this go unattended as it will continue to migrate up the sheathing. Have the insulation and ventilation system upgraded and make sure you install an ice and water barrier if you are replacing the roof.