Q. We have a light grey colored duroid shingled roof. On the north side of the house, the roof is marked with black streaks that are very unsightly. We believe it is caused by moss but have also been told it could be because the roof isn't vented properly. There was some moss, but we hosed that off and are left with the black streaks. Is there a product that will clean these duroids up?
A. These marks are algae marks easily removed by mixing my Shell Busey’s Home Cleaning Formula (4lids into 2 gallons of hot water) and spraying on the roof. Then leave it for mother nature to clean off the black residual. You may have to apply two coats 1 week apart.