Protect Your Home Series---Ice Dams

When do ice dams develop? • When there is snow and/or ice on the roof for an extended period of time and • The outside temperature is below 32 degrees Fahrenheit for Several days and • There is heat inside the attic. What causes an ice dam? • Heat build-up in the attic due to improper ventilation warms the roof and melts the bottom layer of snow and ice. • The melted snow and ice runs downward under the snow layer until it reaches an area of the roof that is colder than 32 degrees Fahrenheit (usually at the caves or gutters). • The water freezes creating an ice buildup called an "ice dam." • Attic heat warming the roof surface melts the snow, creating a pool of water under the snow above the ice dam forcing water back up under the shingles causing water to leak into the building. How can I prevent an ice dam? • Keep the attic and roof cool by installing adequate insulation on the attic floor. • Ensure that there is proper ventilation by installing soffit vents that move air upward to a ridge vent or other venting near the roof ridge. • Wrap or insulate all heating ducts in the attic. • Seal all openings to the attic (e.g. light fixtures) • Keep gutters and downspouts clear of leaves and natural debris • Use a snow rake or soft broom to remove fresh snow from gutters. (Avoid using sharp tools to remove ice as this usually causes more damage.) Will ice shields and heating cables prevent ice dams? • Ice shields and heating cables do not prevent the formation of ice dams as they do not address the root cause of ice dams. • Only proper insulation and ventilation will reduce the probability of ice dams.