If you or your neighbors happen to notice a slight roof discoloration, more often than not, it will be caused by a common type of algae that is known as Gloeocapsa Magma.

Categorized by uniform dark black or grey streaking on a roof’s shingles, Gloeocapsa Magma is an airborne algae that has the propensity to spread spores from home to home within a neighborhood. While this algae is mostly an aesthetic nuisance, with time, the moisture retained in the algae can possibly age the shingles prematurely.

Asphalt shingles are more prone to discoloration, as the algae feeds off the calcium carbonate within this type of shingle. Additionally, any north-facing or tree-covered roof angles are much more disposed to growing Gloeocapsa Magma, since the algae thrives in moisture and shade.

While this type of algae discoloration is by no means ideal, it is not a huge cause for concern. However if the stains have a green tinge, the source of the problem is more likely moss growth from overhanging trees, which can lead to serious damage. Here’s what you should know:

Moss Growth and Your Roof

As moss continues to grow, it will seek out the darker and cooler areas of your roof in order to thrive.

Unfortunately, this means moss could be creeping underneath your shingles, causing moisture damage to your roof deck or premature curling.

Moss is notorious for spreading and can potentially damage shingles at a much faster rate than algae. This is why it’s of the utmost importance to trim back tree limbs that are close to your roof line.

How to Solve Roof Discoloration

To combat roof discoloration, you can use a topical cleaning solution; preferably one that can be gently sprayed on the surface of your roof.

There are a variety of options: sodium hydroxide, trisodium phosphate, oxygenated bleach, chlorine bleach solution, etc. These cleaning solutions can either be mixed at home or there are a plethora of manufacturers who sell bottled products for roof cleaning.

Non-Chemical Options for Roof Discoloration

If you’re looking for a roof cleaning option that does not contain chemicals, you should consider installing a zinc or copper strip along the ridge line of your roof.

The metal elements contained in the zinc or copper provide a “poisonous” bath to algae living on shingles, as rainwater passes down from the ridge into your gutters.

If you happen to have existing stains from algae, you may notice the growth patterns trend away from any areas of your roof with metal flashing installed around chimneys, vents, etc. Installing an entire ridge line strip of zinc or copper, with 2-4 inches of exposure, has proven to be an effective defense against algae growth across a wide variety of tiles and shingles.

Regardless of the option you choose, be sure to do extensive research on the possible negative effects of your chosen method; ensuring the solution is safe for the environment, your siding, landscaping, gutters, and groundwater after run off.

We hope you’re finding our roofing blog insightful and entertaining! To learn more about what Eagle Watch Roofing can do for your next roofing project, visit our ‘About Us’ page; or, visit our ‘Testimonials’ page to see what some of our satisfied customers have to say about their experience.