The cold season brings snow-packed roofs across the country and with snow melt can come damaging ice dams. Without properly insulated attics, however, homeowners could find themselves with an ice dam upstairs. Heat from attic melts snow on roofs and the melted water pools and gets in the house. Here are some tips on how to avoid these frosty formations and what to do if they appear.
What is an Ice Dam?
An Ice Dam is a ridge of ice that forms at the edge of a roof and prevents snow (water) from draining off the roof. The water that backs up behind the dam can leak into a home and cause damage to walls, ceilings, insulation and other areas. Ice dams can be prevented by controlling the heat loss from your home.
– Make the ceiling air tight so no warm, moist air can flow from the house into the attic space
– After sealing air leakage paths between the house and attic space, consider increasing the ceiling/roof insulation to cut down on heat loss by conduction
– Natural roof ventilation can help maintain uniform roof temperatures
– Don’t heat the roof, keep it cold. The best way to maintain low temperatures is by ensuring adequate insulation and sealing gaps that let warm air pass into the attic from the house
– Attic needs to be well-ventilated, where cold air is introduced into the attic and heated air escapes rapidly
– If gable and ridge vents do NOT generate sufficient air movement to dissipate the heat, you will need a motorized vent at one end of the attic to exhaust the heat and an adequately sized vent to draw cold air in
– Proper new construction practices begin with following or exceeding the state code requirements for ceiling/roof insulation levels
– Absolutely necessary practice is to contract, 100% effective air barrier through the ceiling (Should not be any air leakage from house to attic space)
– Recessed lights, skylights, complicated roof designs and heating ducts in attics will all increase the risk of ice dam formation
When you have an Ice Dam
-Often get parallel lines of moisture on ceiling – dark lines in the ceiling are called shadow lines.
-Trusses are exposed to low winter temperatures and act like a thermal bridge to ceiling below creating a cold strip on ceiling where condensation forms. Over time, moisture traps dust and results in mildew growth – showing up as shadow lines.
-Clean off mildew with solution of 1 quart bleach and 3 quarts warm water. Rinse surface with clear water and let dry.