Ice dams are a mystery to many homeowners. That’s because heat, ironically, is a major cause of this damaging phenomenon. If your entire roof remained a uniformly frigid temperature, ice dams would rarely occur.
How Ice Dams Happen
The problem starts when the upper area of the roof near the peak is disproportionately warmed by excess attic heat. This causes snow and ice accumulation at that portion of the roof to melt quickly, sending water flowing down the shingles toward the gutter. However, as the water reaches lower parts of the roof not warmed by the attic, it quickly refreezes, steadily forming an ice barrier on the eaves that obstructs flow of roof runoff into the gutters. Soon, trapped water begins pooling on the roof.
What Happens When They Do
Your shingles shed moving water as it flows down the roof. What they aren’t designed to do, however, is resist standing water. Pooled water penetrates the shingles, flows between the joints of roof sheeting and leaks into the attic. Wooden structural components are saturated and insulation is soaked. Eventually, water damage begins to appear in the ceiling of living spaces.
How to Prevent Ice Dams
Make sure the entire attic is as uniformly cold as possible:
- Locate and seal air leaks between the living quarters and the attic. This includes caulking cracks at wall and ceiling joints, as well as around recessed ceiling light fixtures and pipe or vent penetrations.
- Verify that the attic hatch or pull-down stairs seal properly.
- Upgrade attic floor insulation to current Department of Energy standards by adding an additional layer atop existing insulation if required.
- Make sure attic ventilation is adequate. The size of exhaust vents at the ridge should match the intake vents down at the soffits. Total ventilation space at both the ridge and soffit vents should equal one square foot per each 300 square feet of attic floor.
V is for Victory in keeping ice dams off your roof this winter. In Canton, Sharon, Foxboro and Dover, contact the experts at Victory · Heating · Air Conditioning · Plumbing.
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