These guys are awesome! Like most in Virginia, my older brick home was covered with black mold (atop a 15-year old roof), lichen (under trees) and algae (on brick surfaces including steps). Brian and Jon removed it ALL. (Except for now-dead roof lichen which will take time to wash off naturally). Brian and Jon even rug-scrubber-like machined the black mold off my relatively new sidewalks. I asked, and they were very careful to use low power wash on the roof, to prevent damage to the asphalt shingles, and on woodwork, to spare my recent paint work there. They also used eviron-friendly chemicals, taking care to bag the runoff from gutter spouts. Finally they treated plants and flowers with fertilizer to restore them. Now my house looks brand, spanking new. And there is a 5-year sliding warranty should the roof black mold return. This is certainly more cost effective than getting a new roof, and everything else is clean!