While winter scenes with icicles hanging from the eaves of amber-lit homes have sold plenty of Thomas Kinkade prints, the reality of these ice formations is that they may be indicating some problems underneath the accumulation of snow on the eaves. Specifically, icicles hanging from the roof indicate the formation of an ice dam, which is formed by an imbalance of temperatures on different areas of the roof.
Ice dams start with an accumulation of snow on a rooftop. Heat escaping from the interior of the structure then starts melting the snow, which runs down the roof toward the eaves which, due to their extension past the exterior wall, are not exposed to radiating warmth. If the surface of the eaves is cold enough, the snowmelt re-freezes upon contact and starts building a bank of ice that traps water that collects on the warmer area of the roof, hence the name “ice dam”. In situations where the amount of runoff exceeds the holding capacity of the ice dam, water will run over the top of the bank, where it re-freezes to form icicles. At the same time that icicles are being formed, the amount of water that remains trapped behind the bank of ice can grow to the point where it starts saturating the substrate beneath the shingles.
To make matters worse, if the weather stays cold, large ice dams tend to build on themselves trapping more water and saturating more square footage on the roof. If left unchecked, constant saturation can break down the roofing system to the point where several leaks start at the same time, which can cause a high degree of damage to the structure as well as insulation, flooring, paint and drywall inside the building. On the exterior of the structure, gutters can be separated from the roof and the growth of the formation can steadily increase load bearing stress.
If you’re seeing icicles on your roof, there’s a good chance that an ice dam is directly behind them. Rather than attack the ridge with an ax, an ice pick or another tool that can damage the roof and/or the gutters, call a professional to execute the removal process. After its removal, take the necessary steps to prevent subsequent ice dams from forming. These steps include adding insulation, venting the attic, and insulating ducts that radiate heat into the attic. The result of taking these steps will be the elimination of the primary cause of ice dams; the temperature imbalances on the roof’s surface that melt and then re-freeze snow accumulations.
