Big Easy Roofing has published a new educational article addressing one of the most persistent questions the company hears from residential customers: whether the dark streaks and green patches that appear on asphalt shingle roofs in humid climates are cosmetic issues or the early stages of structural damage. The guide, titled Does Roof Algae and Moss Actually Damage Your Shingles, explains how the two organisms differ and why the distinction determines how quickly a homeowner needs to respond.
According to the article, algae and moss cause damage through entirely different mechanisms. Algae, the flat dark streaks running vertically down a roof surface, is caused by the organism Gloeocapsa magma and feeds on the calcium carbonate filler in modern asphalt shingles. Over years, the colonies loosen the bond between protective granules and the asphalt substrate, and the dark coating absorbs solar heat that accelerates thermal aging. On a New Orleans roof, untreated algae over 5 to 10 years can reduce effective shingle life by 5 to 10 years compared to a roof that is cleaned periodically.
Moss operates on a shorter timeline and through a different mechanism. The article explains that moss uses rootlike structures called rhizoids that physically grip and lift shingle edges, creating a direct entry point for wind-driven rain. It also retains moisture against the shingle surface for days after a rain event, accelerating granule loss far faster than algae alone, and it traps debris that redirects water flow in ways that can drive rain past shingle joints. In heavily canopied Uptown, Carrollton, and Mid-City neighborhoods, moss growth on north-facing slopes under mature live oaks is a recurring finding during inspections.
Lichen, the crusty gray-green patches that sometimes appear on older roofs, sits between algae and moss in severity. The guide notes that the primary risk with lichen is during removal, since aggressive scrubbing or pressure washing pulls granules away and leaves bare spots on the shingle.
"Homeowners get conflicting advice on this from every direction, and most assume the streaks are ugly but harmless," said a spokesperson of Big Easy Roofing. "The reality is that algae is a slow problem and moss is a fast one, and treating them the same way is how a fifteen-year-old roof ends up needing replacement at seventeen instead of twenty-five. This guide walks residents through the difference so they can decide whether to schedule a cleaning now or plan for next year."
The article closes with specific action thresholds. Algae warrants scheduled cleaning when visible streaks appear on more than one roof plane, typically by year 3 to 5 in the New Orleans climate, with repeat treatment every 2 to 3 years. Moss requires action within the same season it is noticed, since lifted shingle edges create leak risk during every subsequent rain event. Lichen can generally wait for the next scheduled maintenance unless it covers more than 10 percent of the roof. The guide warns against pressure washing any asphalt roof, citing Asphalt Roofing Manufacturers Association guidance that the practice causes granule loss and can void warranties.
A frequently asked questions section addresses whether algae-resistant shingles prevent moss, whether insurance covers cleaning, and how to distinguish the three organisms visually. The article also notes that Big Easy Roofing assesses algae, moss, and lichen conditions during every roof inspection, and that the company's 24-Hour Roof Replacement Program remains available for homeowners whose inspection reveals damage beyond what cleaning can address.
Big Easy Roofing is a residential and commercial roofing contractor serving New Orleans, the surrounding parishes, and portions of Louisiana and Florida. The company handles replacement, repair, inspection, and insurance claim assistance.
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For more information about Big Easy Roofing, contact the company here:
Big Easy Roofing
Jose Yoder
(504) 800-8196
info@bigeasyroofing.com
517 Soraparu St 103 E,
New Orleans, LA 70130
