Dark streaks on asphalt shingles can be alarming, but appearance alone doesn’t tell you what caused them or whether a roof needs repair. The first step is to identify what you’re looking at—and check the roofing manufacturer’s care instructions before choosing any cleaning method.
The Asphalt Roofing Manufacturers Association (ARMA) explains that algae discoloration can look like soot, dirt, moss, or other debris. It also distinguishes algae streaks from moss and recommends consulting the shingle manufacturer about moss removal. Its technical guidance, updated June 6, 2024, warns against using a power washer or scrubbing tools on asphalt shingles because they can damage the roofing surface and loosen granules.
A homeowner’s roof-care checklist
- Don’t diagnose from a photo alone. Streaks, moss, lichen, and debris can look different and may call for different next steps.
- Check the roof’s product guidance. Follow the shingle manufacturer’s approved cleaning recommendations; ARMA says methods and solution directions can vary by manufacturer.
- Avoid pressure washing and scrubbing asphalt shingles. ARMA says high-pressure washing can damage asphalt roofing and should not be used to remove algae or other stains.
- Keep people off the roof. ARMA warns that roof cleaning makes the surface slippery and recommends that only trained professionals work on roofs.
- Protect the rest of the property. Any approved cleaning method should account for nearby siding, fixtures, landscaping, and runoff, following product labels and local requirements.
Roof care is a good example of why the strongest spray isn’t automatically the right tool. Surface type, manufacturer instructions, worker safety, and the surrounding property all matter.
We’re sharing practical exterior-care guidance as United We Shine prepares for its planned full-service launch in Spring 2027. Online bookings are coming soon. See our planned services or visit the forms page for updates.
Source
Asphalt Roofing Manufacturers Association: “Algae Discoloration of Roofs” (technical guidance dated June 6, 2024; reviewed November 14, 2026). Consult the specific shingle manufacturer for product-level instructions.
Written by Robert E. Allen Jr. The featured graphic is an AI-generated illustration; it does not depict a United We Shine customer job.
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