What is an ice dam?

An ice dam is defined as a ridge of ice that forms at the edge of a roof, preventing melting snow from draining off the roof surface. This phenomenon occurs when the temperature conditions vary across the roof, leading to the melting of snow on warmer sections while colder edges remain frozen. As the snow melts, the water flows down the slope of the roof but gets trapped by the ice dam, creating a pool of water behind the dam. This trapped water can lead to leaks and water damage inside the building, making it essential for roofers and homeowners to understand and mitigate the risks associated with ice dams. Recognizing the formation of ice dams and addressing it through proper insulation, ventilation, and roof design can help manage this issue effectively.