Ice dams in Seattle form when warm attics melt snow that refreezes at eaves, forcing water under shingles

https://messiahrvxo831.theburnward.com/asphalt-shingles-vs-tile-roofs-for-king-county-1

Ice dams in Seattle form when warm attics melt snow that refreezes at eaves, forcing water under shingles. Continuous soffit-to-ridge ventilation, air sealing, and eave ice-and-water shield stop hidden winter leaks.