What dark streaks can mean
Algae can cause black discoloration on asphalt shingles, and tile surfaces can develop organic growth. Appearance alone cannot determine roof health. Active leaks, missing pieces, and visible deterioration warrant attention from a qualified roofing professional.
Why aggressive pressure is a concern
High-impact water can dislodge shingle granules or damage roofing components. Tile can be fragile under foot traffic, and the surrounding roof system also needs protection. Avoid treating roof cleaning as an ordinary concrete-washing job.
What should be assessed?
Material, pitch, height, access, drainage, roof condition, and nearby landscaping affect a cleaning plan. Tell the contractor about prior repairs, warranties, solar equipment, and drainage concerns. Ask how runoff and adjacent surfaces will be handled.
Results and follow-up
Cleaning may improve organic staining, but it is not roof repair and does not guarantee a longer service life. Some changes can occur gradually after treatment. Ask what to expect for your roof and how to report concerns. Keep manufacturer maintenance instructions and any written scope for reference.
Follow material manufacturer instructions and seek an assessment for your home’s actual condition. Cleaning is not a substitute for repairs.