It is a type of algae that feeds on your limestone filler in your shingles.
How come I've never seen that black stuff on my roof until the past few years?
The particular type of algae that feeds on your shingles migrated from the Gulf states 6-7 years ago, which is why most North sides of roofs have those blacks stains in our area.
Do you use a pressure washer to remove those stains?
NO. We don't use low pressure or surface cleaner either. We use a roof pump specifically designed to gently remove the algae from your shingles without removing those little granules on them.
Premier Power Wash & Roof Cleaning specializes in soft washing and non pressure roof cleaning. We are fully insured and proudly serve all of Chester County and Delaware County PA.
Call 610-220-3590 for a FREE estimate.