So what’s the dark stains on my roof?
The dark algae pigmentation you see growing on your roof is what protects the algae from the sun and allows it to grow. The most prevalent growth and where it first starts to form is on the north side of the home as that is the last side to dry so gives the best conditions for growth.

Algae growth should not be pressure washed or scrubbed off. When you take an “abrasive” to your roof, you are running the risk of removing the granules that are protecting your shingles! This will take years of life off of your roof.

This graphic places us right in the transition area between medium to high for the potential of algae growth. But as we know being in Illinois, we have the potential to be any climate just dependent on the day/year.

To learn more about Algae growth, you can check out;
3m.com/resistblackstreaks

To maintain Scotchgard certification a shingle needs at least 10% copper granules with a uniform distribution over the surface. This is the only way to properly fight against algae growth. For each production run of shingles a sample must be sent to a third party for testing.

Interesting fact: in the 1950s, 3m scientists noticed that the areas below flashings and pipes algae growth was inhibited. The ionization of roofing below these areas were algae resistant which started the pursuit on how to best utilize it. This led to this new method of production.

Malarkey Roofing was the first manufacturer to receive the Scotchgard Protector designation from 3m. Learn more about Malarkey Roofing products on our page here.

Additional information about how they tie in their granules into the NEX rubberized asphalt technology can be found here.

Perfect Exteriors Inc.
Protecting Naperville, La Grange, Hinsdale and the surrounding Chicagoland from unsightly roofs and premature roof replacement since 2011