What Are the Black Streaks on Your Arkansas Roof?
If you have dark streaks running down your roof — especially on north-facing slopes and shaded areas — you are looking at Gloeocapsa magma, a cyanobacteria that thrives in humid climates like Arkansas. These organisms feed on the limestone filler in asphalt shingles and spread through airborne spores from neighboring properties.
Why Black Streaks Are a Problem
The streaks are not just cosmetic. Gloeocapsa magma breaks down the limestone aggregate in your shingles, reducing their reflective properties and accelerating aging. Left untreated, algae colonies allow moisture retention under the granules, which leads to premature shingle deterioration and can eventually require full roof replacement years earlier than expected.
In Arkansas’s hot, humid summers, black streak algae spreads faster than in drier climates. A small patch can cover a significant portion of your roof within two to three growing seasons.
The Right Way to Remove Black Streaks
The ARMA (Asphalt Roofing Manufacturers Association) recommends low-pressure soft washing with a sodium hypochlorite-based solution as the approved method for removing algae from asphalt shingles. High-pressure washing strips the protective granules and voids most manufacturer warranties.
Soft washing kills the organism at the root and typically keeps roofs clean for 2–4 years depending on shade exposure and proximity to neighboring infected roofs.
Roof Soft Washing in Central Arkansas
American Services AR provides roof soft washing throughout Conway, Little Rock, Benton, Bryant, Cabot, and surrounding areas. Call 501-289-5623 or visit americanservicesar.com/roof-cleaning/conway/ for a free estimate.