Black streaks on an asphalt shingle roof are gloeocapsa magma, which is a very common mold that grows on the backside of a tree.
But what causes this mold to appear? Aside from being ugly, is there any concern with these blacks streaks? Are they dangerous? Are they permanent? If not, how do you get rid of them?
What Causes Roof Mold?
The reason roof mold has become so much more prevalent today than it was 20 years ago is because today’s asphalt shingles are made with more fillers, instead of actual asphalt—which is an oil based product—in order to keep the cost of the shingle down.
The filler manufacturers use most commonly is crushed limestone. The gloeocapsa magma, the mold, can thrive on the limestone, therefore causing more mold. That’s the biggest problem today causing black streaks. The Midwest and the northeast is where the problem is most common.
Is Roof Mold Dangerous?
Gloeocapsa magma by itself is not necessarily dangerous. Again, it grows on the back of a tree. However, it can migrate into an attic space and then become attic mold. This becomes dangerous for one major reason, which is allergies.
Studies show that allergies have increased by 600% since the 1970’s, due to attic mold. In extreme cases, people have actually gotten lung infections and so forth, caused by severe cases of attic mold.
How to Get Rid of Roof Mold
To get rid of roof mold, it is ill advised to power wash or use any type of high-pressure rinse. Typically, even what companies refer to as a “low-pressure” rinse is a pressure washer just set at a low setting. And that will still cause damage and shorten the life of the roof.
The best solution is to use an environmentally friendly cleaner. We have a product that we use and there are a few good products on the market. This cleaner is simply sprayed on to treat the roof, and then the rain naturally rinses the roof off over time.
On average, if you treat a roof properly with a good product and then allow standard rainfall to assist in the process, a roof with up to seven years of mold buildup will be cleaned off within two or three months.
What Can Go Wrong with Roof Mold?
If you don’t take care of the black streaks on your roof, there are two things that will happen.
One, the home will look aesthetically displeasing.
Two, over time, when the black streaking becomes very heavy, it will start to dislodge the gravel coating on top of the asphalt shingles. As the coating dislodges, the shingles become exposed to UV rays, which cause them to age faster by making them hard and rigid.
The lesson here is that it’s very important to remove the streaking off of a roof, especially as it gets considerably darker over time.