black streaks on house and roof · Manchester, GA

black streaks on house and roof in Manchester

In Manchester, this comes up on mill-town brick and practical family houses. Older industrial-town concrete is stained in layers — clay, mildew, and rust. North slopes and walls under pines show it first. If the street face is clean and the back is black, that is the shade, not a half-finished wash.

Brick holds damp. Gutters and downspouts matter here more than decoration.

The organism most people are looking at on asphalt shingles is an algae that protects itself with a dark pigment. It runs with water and leaves the streak. On siding, mildew and algae make a similar dark film, especially where a sprinkler or a tree keeps the wall damp. Sodium hypochlorite kills it. A brush and a garden hose smear it.

Killing it does not change the conditions. If the wall stays shaded and wet, a new film will start. In this part of Georgia and east Alabama that is often visible again within a year or two on the worst elevation, and longer on a sunny wall. We will not sell an annual result as a ten-year result.

If the “streak” is actually granule loss, or a tar drip, or a rust run from a metal valley, bleach will not fix the look. We will say which one we think it is when we see a photo. A close photo of the streak beats a paragraph.

The full explanation, without the town attached, is the black streaks are a colony, not dirt article. The town does not change the chemistry. It changes the houses, the shade, and the clay.

Roof soft washing in Manchester →