Believe it or not, that’s algae! Those streaks are Gloeocapsa Magma, otherwise known as “Blue-green algae”. I know, those streaks aren’t blue or green, they’re black, right? If it was up to me, I’d name it BLACK ALGAE
So what causes this black blue-green algae?
Well algae is a plant, so it needs some basic elements such as water. Do we get rain & dew on our roofs in Michigan? Oh yes, we do. Plants also need indirect sunlight. Do these black streaks only appear on the North side of a house? Yeah, hmm.
At this point you may be thinking: “Okay the black streak algae is caused by water & indirect sunlight so there’s no way to prevent it because you can’t stop the sun & clouds.”
The copper solution!
Thanks to our friends at 3M Scotchgard they invented roof shingle granules that are embedded with copper!
Now you’re probably thinking: “Yea so??”
So, Copper is the sworn enemy of algae & the protector of roofs!
Copper kills algae by binding to it, which damages the algae cells, causing them to leak and die.
The International Code Council requires 2% of all shingle granules to be imbedded with copper. Obviously that’s not enough in Michigan!
Make sure the roofing contractor you hire installs shingles that are at least 5% copper granules. Most shingle manufacturers offer shingles that will have approximately 2% – 5% copper granules but companies such as Atlas & Malarkey have offerings up to 10% & 12% copper!
So why in the world would these roofing companies knowingly sell you shingles that will streak black? The conspiracy theorist in me says: planned obsolescence! However, the reality isn’t as sophisticated. Reality is, most roofing contractors just want to give you the lowest bid, which we all know usually means the worst product and the biggest rip off.
Higher copper content shingles may cost you 5% more than the streaking kind, but they will look brand new for decades, till the day you want to sell your home. Think about the resale value.
Resale value. Sounds like another blog may be in the works!
Have a great day, and remember: in home improvement you can only pick two: cheap, fast, or good!