Ice dams are an insulation problem, not a roofing problem

Ice dams form when heat escapes through the roof, melting snow that refreezes at the eaves. The fix is not heat cables or ice-and-water shield (those are band-aids) — the fix is air sealing and insulating the attic floor to R-49 or higher per IECC 2021. Seal all attic penetrations (can lights, plumbing stacks, electrical boxes), then blow in insulation to code depth. This eliminates the heat source that creates dams.