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Roofing granules found around your home, what does it mean?

Doug Gore

New member
They can look like dead ants just scattered all around your home....but look closely.

Have you found roofing granules on the ground around your home?
Why are they there and where did they come from?

Take a good look at your roof and you may notice it "looks" dirty or has black streaks.

But the reality is the roof is being eaten. The granules you're finding on the ground may be the result of the filament root system of the algae that are attacking, and eating, your roof! The algae eats away at some of the minerals around the protective granules in your shingles and can cause the granules to become loose. A heavy rain hits and washes the, now loose, protective granules off the roof.......shortening the life span of your roof shingles.

You could simply sweep away the granules and ignore the problem but there is a simple and cost effective solution that could slow down the degradation of your roofing system. Its a process called "Soft Washing".

Soft Washing was invented by AC Lockyer back in the early 90's. AC, who's background was in horticulture, developed this safe, no pressure way of combating the algae, moss and lichens by effectively killing them AND their root systems. Soft Washing is a process of gently spraying a 100% biodegradable solution onto the roofing shingles to kill the algae. In many cases the roof is then gently rinsed.

Front mix running.jpgMix falling off.jpg

The process was found to be so effective that it is the recommended process for roof cleaning by ARMA (Asphalt Roofing Manufacturers Association) and by roofing manufacturers themselves.

In the "old days" people used to....are you ready?...Are you sure?......People used to use pressure washers to clean the algae from the roof. The use of high pressure often caused more damage then the algae! Roofing manufactures can and will void the warranty of their roofing system the moment a pressure washer is used simply because of the severe damaging effects caused by this type of roof cleaning.

Let's back up for a moment.....you found roofing granules around your home, and now you know why, and you know that Soft Washing is a cost effective solution, but how do you soft wash?

Soft Washing should be left to a professional roof cleaning contractor and we are more then willing to help you find a true professional in your area. Cajun Soft Wash, our company, services much of Southern Louisiana and we are in constant contact with professional roof cleaning companies from Maine to Hawaii to Oregon and beyond!

Feel free to give us a call. We won't charge you for the advice and we wont charge you to assist you in finding a true professional.
But feel free to "Like" us on Facebook.....:} for providing you with the help and expertise you deserve!


Bill Booz

UAMCC Board of Directors
Hey Doug the article looks great, but granules fall off for lots of reasons and fall off on the sunny side. Under extreme heat the shingles become crusty over time and literally fall apart. Some shingles just aren't made well. We have no actual proof that the granules fall off from algae. Lots of people say it, but no one has actually proven it and no roof manufacturer will agree. We also have no actual proof that gloeocapsa magma feeds on the roof materials either. That ones really becoming common and most people don't care if it may be a false claim, but again no one has taken the time to actually prove or disprove it. Unfortunetly it is being repeated by respected publishers all over the world who are trussing that we know what we are talking about. You will find lots of people saying it, but I have read studies from 150years old to today and while some note that it can form on limestone rocks and one even says that further study would be needed to find out if calcium is a food source, none have actually tried to find out or made the claim that it does.
You will find that gloeocapsa magma grows on metal, vinyl and rubber surfaces as well, so I have always had a hard time believing that calcium is a food source, yet it would make sense that calcium may hold more moisture in a shingle and promote the growth of photosynthetic organisms.
I have also consulted with 3M and Owings Cornings about this claim and they repeat what I have said here, no evidence of that exists and it is instead proven to be airborne and grow wherever moisture content is high enough for long enough.

Non of this is meant to insult you, I like your format and respect your effort. Too much misinformation is already spread around with these claims, I am trying to get more people to see the truth. We don't have all the answers on cyanobacteria yet [The phylum under kingdom(bacteria) that gloeocapsa magma is in.] What is known is that they are photosynthetic bacteria of the blue green nature and may have nitrogen fixing properties, that they grow in colonies and lock in more moisture as the colony thickens. This colony then becomes a food source for moss and lichen that do (proven studies) require an organic substance as part of their food. Therefor the biggest threat to an asphalt shingle roof granular system is moss and lichen infestation promoted by the formation of algae colonies. Moss and lichen do remove granules from roofs as can be seen by anyone that removes them. This one is easily proven as you can physically see the roots and see the damage. Many current research projects are ongoing to help better understand how cyanobacteria work.

Bill Booz

UAMCC Board of Directors
gloeocapsa-250.jpgI was reading it again and I just realized AC has been using this 'filament root system' lingo So I looked it up. Guess what a root is? A filament so pretty much any plant root is a filament system. A filament is basically a thread or string. But aside from that funny note (I will call AC after this post) here is what Gloeocapsa Magma looks like. It is a bacteria. It does not have roots of any kind. Also you should know that algae by definition is a laymans term describing any plant like structure that lacks visible roots and leaves. So generally algae are not rooting plants or even plants at all.

Bill Booz

UAMCC Board of Directors
The UAMCC is releasing a 8 page newsletter on this. You can copy some good info from it when it's released.

Doug Gore

New member
Can algae damage my roof?

Can algae damage my roof is a question that gets answered differently on a daily basis, just like as noted above. The question becomes more about the evidence, common sense and the science over the source. Algae is also a somewhat "loose" term. The black streaks are actually Gloeocapsa magma and may resemble "algae" in that they are green, but they are actually a cyanobacteria.

First I think it’s important to understand how a roofing shingle is made. Without getting into the technical side of things the basics of a roofing shingle are:
A base sheet, usually made from fiberglass, is saturated with molten asphalt. This molten asphalt generally consists of a large amount of filler (limestone dust). Then protective granules are added to the top. A very basic explanation but this is how most asphalt roofing shingles are generally made.
Although I can’t stand the way this lady pronounces “Ashphalt” there is a video that helps see the process in action which can be found at https://www.youtube.com/watch?v=mZ7VQmgosyU.

I have seen many articles where the authors state that algae do not harm roofing shingles. In those same articles I will see some sort of comment on the alga living off the limestone or “filler” as it is often referred to. I recently read an article by a Chicago reporter who often writes about home improvements. As such you would think his articles would be based more on fact and filled with truth and helpful insight. Instead, I believe, his article was filled with contradictions. I found myself wondering how any homeowner, or commercial property owner, could make an informed decision when faced with such articles……which ultimately inspired me to write this article. As you read on I want you to use your own sense of what really makes sense.

In his article the writer states (referring to the black streaks on your roof):
It's a harmless algae that's gorging itself on the powdered limestone filler that's often added to the liquid asphalt in shingles to help add weight to them.”
As I read his statement I found myself wondering how the author could find the algae as “harmless” while in the same breath he states “gorging itself on the powdered limestone filler”. So the algae are gorging themselves on my roof but they are harmless? This same author went on to make the statement “……..manufacturers had a problem getting the shingles up to the minimum weight requirement. Someone decided to use powdered limestone dust -- but they didn't realize that it was a delectable food for the tiny algae. Fortunately, the algae doesn't harm the shingles” Again stating the limestone dust was a food source for the algae then stating the algae does not hurt the shingles.

My question to the author of that article would simply be; how can you admit the algae eat the limestone dust yet state they do no harm to the shingle?

First we need to ask: what is the purpose of the limestone dust?
The limestone dust is used, as the author states, to add the needed weight to the shingles. So if the algae eat away the limestone they are therefore removing the needed weight. Further, according to Carmeuse, a company that provides the limestone filler to asphalt roofing manufacturers, the limestone filler is used to increase durability and flame retardancy
(source http://www.carmeusena.com/markets/markets-milled-limestone/roofing-shingles). If you allow the algae to “gorge” on the limestone then you are allowing them to remove the durability and flame retardancy as well….thereby harming the shingles (Not to mention being downright ugly).

Now let us go back to how a roofing shingle is made. Remember that the limestone filler is added to the molten asphalt and then the protective granules are added over the top of this molten layer. So, what do you suppose will happen if the limestone dust is eaten away from the manufactured asphalt shingle?

What happens when you take a bite out of an apple? You leave a hole in the apple.
What happens when the algae take a bite out of the limestone? They leave a hole in the shingle.

What happens when you put sprinkles on top of an ice cream cone? You get a delicious treat.
What if you don’t like sprinkles and you eat all of the ice cream? The sprinkles fall to the ground….much like your protective granules.

So let me ask you one final question: Can algae damage my roof?

Cajun Soft Wash serves the Greater Baton Rouge metro area with safe – no pressure, roof and exterior cleaning.
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Doug Gore

New member
We have no actual proof that the granules fall off from algae. Lots of people say it, but no one has actually proven it and no roof manufacturer will agree. We also have no actual proof that gloeocapsa magma feeds on the roof materials either.

Bill, with all due respect, we can pick this apart until the cows come home but I seriously don't see how you can advocate that "we have no actual proof". There are many credible sources out there including all of the roof cleaners who visibly see the difference between the shingles cleaned from the GM and the shingles ON THE SAME ROOF which had no GM. https://microbewiki.kenyon.edu/index.php/Gloeocapsa_magma is a student created page on the subject that I feel has merit....and yes, I could point to many others. The same as you can point to many that say the opposite. Read my post above where common sense should also play a role.

As for the roofing manufacturers......why would they ever want to agree and/or admit the filler (limestone dust) they use is a feast waiting for the GM? I think the proof is further in what they do now......They have created a product to combat the GM and not just because it's ugly!

I think even you could admit there is plenty of evidence the GM feeds on limestone dust. Limestone dust is a core ingredient in the manufacturing of roof shingles. 1+1 generally = 2