Ice dams are typically caused by uneven heat loss from your home in wintry conditions such as snow, heat melting the snow, and cold temperatures re-freezing melted snow. The heat is typically caused by inadequate attic insulation or from warm air seeping into the attic from living spaces below. This causes the roof to warm above freezing temperature, which allows snow to melt and then re-freeze before it reaches the roof’s edge. If this cycle repeats over and over, an ice dam forms and water collects behind it. As the water pools, it backs up under your roofing material and can cause expensive water damage.