The answer to 'why is my architectural shingles ice dams' is that ice dams can form on architectural shingles due to poor attic insulation and ventilation. Ice dams occur when heat escapes from the home, causing snow on the roof to melt and refreeze at the roof's edge, creating a dam that prevents proper drainage.
This can lead to water backing up under the shingles and causing leaks and damage to the roof and interior of the home. Symptoms include icicles forming along the roof's edge and water stains on the ceiling or walls. Solutions include improving attic insulation, adding roof vents, and clearing snow and ice from the roof's edge.