The answer to 'why is my asphalt shingles ice dams' is that ice dams form when heat escapes from your home, causing snow on your roof to melt and then refreeze at the roof's edge. This creates a barrier that prevents proper drainage, leading to water buildup and potential damage to your roof and home.
Common causes of ice dams include poor insulation, inadequate ventilation in your attic, and heat loss through the roof. Symptoms include icicles forming along the roof's edge, water stains on interior walls, and sagging or damaged gutters. Solutions can include improving insulation, adding ventilation, and removing snow from the roof to prevent ice dam formation.