Ice Damming

Ice damming is a cold-climate phenomenon that occurs on roofs where the upper section (near the ridge) is warmer than the lower section (at the eaves). Heat escaping from the building through the ceiling warms the roof surface in the upper zone, causing snow or frost to melt. The meltwater flows down the roof surface until it reaches the colder eaves overhang — which is not heated from below because it extends beyond the external wall. At this point, the water re-freezes, gradually building up a dam of ice along the eaves line. As more meltwater flows down and is blocked by the dam, it backs up under the roof tiles or sheets, entering the roof space. Ice damming is prevented through three complementary strategies: adequate ceiling insulation (to prevent heat from escaping into the roof space and melting the snow), effective roof ventilation (to keep the roof surface temperature uniform from ridge to eaves), and, in severe cases, ice-dam membranes installed beneath the roof covering along the eaves line to provide a backup water barrier. In Gippsland, ice damming is primarily a concern in the elevated areas of the Baw Baw Shire and the northern Strzelecki Ranges, where winter frosts and occasional snowfalls occur. While not as severe as in alpine regions, the freeze-thaw cycle can cause localised ice damming on poorly insulated homes. Town & Country Roofing considers ice dam risk when specifying roof systems for properties in elevated Gippsland locations.