black streaks on roof Georgia · Grantville, GA

black streaks on roof Georgia in Grantville

In Grantville, this comes up on depot-town houses and older commercial brick. Old pours are porous. Clay and mildew sit in the same slab. Pine shade and oak shade feed this. A roof in full sun on a new street can be clean while the wooded lot two streets over is striped.

Drafty doors and full gutters show up first in these houses.

Those black streaks are a colony, not dirt that blew on. Asphalt shingles stay damp just long enough, in this climate, for algae to run downhill with the rain. A roof soft wash is a treatment that kills the colony and lets it release. It is applied so we are not scouring the shingle. The granules that shed in a gutter after a pressure wash were the roof’s sunblock. They do not grow back.

The roof often looks uneven the same day and more consistent after weather finishes the release. If someone promises “white shingles before lunch” with a surface cleaner, they are promising a shorter roof. We will also say no when the shingles are already curling, cracked, or bald. A pretty treatment on a failed roof is a wasted fee.

Metal roofs, tile, and slate are not this article and not this price. They are quoted after we see the finish. We do not treat every roof as asphalt because the truck is already there.

The full explanation, without the town attached, is the black streaks on asphalt shingles are algae article. The town does not change the chemistry. It changes the houses, the shade, and the clay.

Roof soft washing in Grantville →