This quality GAF Leak Barrier helps keep water out of the most vulnerable areas of your roof, including the eaves, rakes, valleys and around the chimneys. It helps prevent costly repairs to your home by helping to protect your home from wall or ceiling staining, which can be caused by wind-driven rain and, in colder areas, damaging ice dams. WeatherWatch protects against ice dams is required at eaves by many building codes wherever the January average temperature is 25°F or lower or where there is a possibility of ice forming in the eaves (Check local building codes for specifications in your area).