Ice dams are caused on a roof where there is heat loss from inside the structure. The heat warms up the roof, melting the snow, which in turn refreezes overnight. The water or melted snow typically will refreeze at the eaves first and continue to expand up the roof slope as melting and refreezing occurs. Thawing water backs up to the frozen ice and causes a dam. This water back up will lead to a variety of performance issues with the roof system and may cause leaking on the internal side of the structure.
If air is allowed to flow under the finished roof assembly, the temperature on the roof will remain cooler and more consistent. A centilation system under the finished roof system can be achieved with Hunter Panels Cool-Vent.
Cool-Vent is a ventilated insulation product that is comprised of a bottom layer of polysio insulation, a middle layet of wood spacers with a 1", 1.5" or 2" airspace and a top layer of OSB or plywood. The length of the rise and run determines which airspace will be the most efficient for your roofing system. Hunter Panels provides a roof ventilation calculator that takes all of these measurements and desired R-Value into account to determine the most efficient system for your building. The finished roofing system- shingles, shakes, metal or tile is installed over the Cool-Vent panels. Cool-Vent also features cross directional airflow keeping the roof temperature constant, further eliminating hot and cold spots on the roof where ice dams are formed.