Disandro Roofing | Roofing Services in Philadelphia, PA 19115

Those common black stains are often Gloeocapsa magma algae, which thrives in our humid climate. While bleach or pressure washing can damage shingles, we use professional, low-pressure soft washing techniques with EPA-registered algaecides. This safely removes the stains without harming your roof's granules or voiding manufacturer warranties, and we can apply preventative zinc strips to inhibit future growth.

This is a classic Philadelphia winter issue caused by the freeze-thaw cycle. Snow and ice melt, seep under shingles into small gaps, then refreeze overnight, expanding and lifting roofing materials. We perform a thorough inspection to find these vulnerable points—often around flashing, vents, or in valleys. Our repair focuses on sealing these areas with durable, ice-and-water barrier materials designed for our climate to prevent recurring leaks.

While algae is primarily cosmetic, it can trap moisture and degrade shingles over time. For leaks, if you see active water stains, mold, or daylight in your attic, it's time to call a pro. For Philadelphia homeowners, we recommend a professional inspection if the algae covers over 25% of your roof or after any major storm or heavy snowmelt. We provide free, no-obligation assessments to give you peace of mind and an expert plan.