Dirty siding

The green stuff on your siding is likely algae, mold, or mildew, which thrive on accumulated dirt, dust, and pollen. This growth typically occurs in shady, damp, or humid areas—often on the north side of a house—and can be exacerbated by poor airflow, nearby trees, or leaky gutters. Regular siding maintenance, including algae removal and mold cleaning, can help prevent these issues.