March 18, 2026 · 5 min read
Those dark vertical streaks running down an Arkansas roof are not dirt, soot, or worn shingles. They are a living organism, and the way you remove them determines whether your roof gains years or loses them.
The Streaks Are Algae, Not Stains
The culprit is Gloeocapsa Magma, a blue-green algae that feeds on the limestone filler in modern asphalt shingles. It thrives in exactly the conditions Central Arkansas provides all summer: heat, humidity, and shade from mature trees.
It spreads by airborne spores, which is why entire neighborhoods develop streaking within a few seasons of each other. North-facing slopes and any area shaded by overhanging limbs go first.
Why It Matters Beyond Looks
The algae mat holds moisture against the shingle surface and loosens the protective granules that shield the asphalt from UV. As granules wash away, the shingle bakes and ages faster, and heat absorption from the darker surface pushes attic temperatures up.
Left long enough, the same damp conditions invite lichen and moss, which root into the shingle and cause physical damage when they are removed.
Never Pressure Wash a Shingle Roof
High pressure blasts away the granule layer, drives water under the shingle courses, and can lift or crack shingles outright. That kind of damage is exactly why a roof should never be cleaned like a driveway.
It also does not solve the problem. Pressure removes the visible surface growth but leaves the organism behind, so the streaks return within a season.
How Roof Soft Washing Works
Roof soft washing applies a low-pressure cleaning solution that kills the algae, moss, and lichen at the root, then rinses gently. The roof continues to lighten over the days that follow as rain carries away the dead organic material.
Before any solution is applied, we pre-wet and protect landscaping, cover sensitive plantings, and control runoff. Gutters and downspouts get attention at the same time, since that is where the dead material collects.
When Should It Be Done?
The right time is when you can see it. A one-year warranty is available on qualifying roof services — coverage depends on the surface and the project agreement, so ask us to explain what applies to your roof before work begins.
If you can see streaking from the street, the algae is already well established — the sooner it is treated, the less granule loss it causes.
Related Services
Ready to take care of this on your property? Start with roof soft washing or gutter cleaning, or call and we will help you decide.
