The answer to 'why is my downspouts ice dams' is that ice dams form when snow and ice melt on the roof and then refreeze at the edge, causing a blockage in the downspout. This can happen when there is poor insulation or ventilation in the attic, allowing heat to escape and melt the snow on the roof. The melted water then refreezes at the colder edges, creating a dam that prevents proper drainage.
Ice dams can lead to water damage in the home, as the backed-up water may seep through the roof and into the walls and ceilings. Symptoms of ice dams include icicles forming on the gutters, water stains on the interior walls, and water pooling on the roof. To prevent and resolve ice dams, homeowners can ensure proper insulation and ventilation in the attic, clear snow and ice from the roof, and install heated cables or other de-icing systems on the gutters and downspouts.