A Guide on Moss and Algae Roof Stains

Homeowners (and a few people who don’t know better) often interchange moss and algae, especially in the context of roofing. Both are a nuisance, after all, as they tend to spread across the roof quite quickly, especially during humid seasons or if you have a leaking roof, and jump from one roof to another in a span of months, even weeks. One of the most common is that they leave behind stains or discoloration on your roof, which, while harmless, doesn’t look nice.

Moss and Algae Roof Stains

Still, there are a few ways to go about getting rid of them, even preventing them altogether. In today’s post, The Great American Roofer discusses what you can do if you’ve been saddled by this problem.

Moss vs. Algae

The first thing to do is to identify which organism is on your roof. They may be similar, but there are notable differences between them, notes your roofing contractor.

Moss is a plant, which looks like small, fluffy green growth clinging closely to surfaces. In the Northern Hemisphere, moss often grows on the north-facing surfaces, such as on trees or roofs, or the side where it can receive the least amount of direct sunlight. 

Algae, meanwhile, is also called mold or mildew. Algae look like blue-black stains on a surface, especially of the species called Gloeocapsa magma or blue-green algae. Their dark pigmentation is a response against the ultraviolet radiation of the sun.

Both moss and algae reproduce using microscopic spores, which are carried by the wind. In addition, they are not harmful by themselves, only that their presence means an excess of humidity on your roof. This means a damaged roof or a leaking one.

Using a Chlorine Bleach Solution

A home remedy for moss or algae growth is by mixing equal parts of chlorine bleach and water, then using a sprayer to apply it on your roof. This mixture can kill moss and algae effectively, and you can rinse them off after 15-20 minutes; if they’re not completely removed yet, you can apply the solution again, wait 15-20 minutes, and then rinse again.

Use GAF’s StainGuard Plus™ Technology

GAF, the manufacturer of advanced roofing materials—and whose products we offer—also employ the StainGuard Plus technology. It uses specially engineered capsules that release copper microsites, which destroys algae cells, on demand, instead of old GI copper strips, that are active even without mold growth. StainGuard Plus’s system allows a more long-lasting protection, and for a more even, comprehensive protection.

For functional yet aesthetic roof installation, you can never go wrong with The Great American Roofer. To learn more about us, call us today at (201) 825-2955. You can also fill out our form to get started.