Ice Dams are a concern for investors, facility managers, property managers, and homeowners. A barn never has ice dams due to uniform roof temperature. Differential roof temperatures caused by uneven insulation thicknesses cause a melting at one location and freeze prior to leaving roof For a heated building it is important to get the insulation to all have the same performance or “R” value. It is a double benefit of less fuel & less ice dams to add insulation and create a uniform roof temperature. Do loop in with a Structural Engineer to see if snow loads increase due to more insulation.