Federal Way Roofing: Article About Roof Mold, Moss and Algae
The moist weather in the Puget Sound area is very hard on roofs. All kinds of mold, moss and algae finds its way to roof surfaces and takes up residence. Many homeowners aren't sure if they need to do something about the problem or not.
One of the most common organisms that take up residence on asphalt shingle roofs is blue-green algae. It looks like black mold to most people. It forms black streaks and stains that are particularly obvious on light-colored shingles. One simple solution to the problem is to have Federal Way Roofing replace the light-colored shingles with dark-colored shingles. The black streaking won't be as unsightly.
Another option is to have special shingles with copper granules embedded in them installed. The copper kills blue-green algae that try to take up residence. If the shingles are in fine shape and don't need to be replaced, a roofer can install strips of copper or zinc along the top of the roof. These strips release toxic metals that wash down the roof each time it rains, helping to control the growth of algae.
Blue-green algae don't actually cause any damage to asphalt shingles. It just looks unsightly, and it can be washed off fairly easily by an experienced roofer. Avoid the temptation to rent a power washer and try a DIY roof washing. Power washers can easily damage shingles.
The roofing experts at Chase NW of Federal Way WA can assist you with any questions regarding commercial roofing or residential roofing.
Washing a roof too frequently, especially with strong chemicals such as bleach, may also cause shingle damage.
Moss is another common roof inhabitant. Moss is usually green and grows around the edges of the shingles. Unlike algae, moss does damage shingles. Moss only grows in shady areas, so one way to control it is to trim back trees that shade the roof. Because moss damages the roof, it's a good idea to remove it frequently with a brush; avoid chemicals and powerful water jets. Scrub it away manually with a long-handled brush and consult a roofer about installing the copper strips or copper-embedded shingles discussed above. These measures control moss as well as blue-green algae.
Roof discoloration that develops only under an overhanging tree is usually not a growth of some kind. It's probably just a stain caused by organic matter falling from the tree. Trimming the tree back should prevent further discoloration. Occasionally, the discoloration will be due to the growth of lichen feeding on the organic debris deposited by the tree, which can be confirmed by visual inspection. If so, the lichen should be scrubbed off. An experienced roofer can help identify the problem and provide advice on removing the discoloration.
Although molds are often blamed for roof stains, molds themselves rarely grow on asphalt shingles. Most "molds" are just algae infestations.