Roof Shingles with Black Streaks


Sep 26th, 2008 by Roof Cleaner Guide.

Black streaks roof stains on roofs in Kansas, Missouri, Oklahoma and Arkansas

This summer driving through Kansas, Oklahoma, Missouri and Arkansas nearly 60% of roofs were covered in black streaks and the tell-tale signs of roof mold and algae. It has become increasingly more common to see these stains across the United States as roof mold and algae continue to spread North and West from the Atlantic and Gulf Coast areas where the stains were most prominent in the 1990s.

The tell-tale signs of roof algae (sometimes called roof mold) are:


* Initial Roof Algae dot

Roof Algae spreads through wind, bird and even small animals. Initially a few roof mold cells will land on the roof. Once the roof mold lands, it finds the crushed limestone in the shingles as a source of food. Between the Moisture, Food, and Sunlight the roof algae has everything it needs to reproduce and build a colony.
At this stage you may not even notice the roof mold because it is so small.
* Roof Algae spot


As the roof algae reproduces, the colony expands and become noticeable from the ground. At this point there can be over 500,000 roof algae cells (which is why it is visible from the ground). By this point roof cleaning should be performed to prevent further growth.

* Triangle Shaped Roof Algae Colony


By the time the roof algae colony takes the shape of a triangle, it has been growing for over 18 months.

Why does the colony take this unusual shape?

As the seasons progress, rain and wind will cause the roof algae colony to be dragged down the roof (appearing as black roof algae streaks). Also, when rain occurs the wind may also blow the colony to the left or right of the streak. The makes the lower parts of the roof algae streak wider than the point at the top. Over a season of rainstorms, this causes the colony growth to take on the shape of a triangle
* Black Roof Algae Sheets


At the point that many Triangle Shaped Roof Algae Colonies join together to appear as a black roof algae sheet, the roof appears to have more black roof algae than roof shingle visible. The upper part of the roof may continue to have a few peaks where the upper roof algae triangles first formed. At this point a Roof Cleaner is needed fast, before the cost of roof replacement becomes needed.