Black mold vs. “harmless” mold.

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Wood destroying fungus on the floor joists of a recent project caused significant structural damage. Notice it is green-grey in color. (Photo by Intellivent.)

In my line of work, I hear people refer to black mold as the “bad” kind.  “Oh, that’s black mold.  It’s the most dangerous type.”

This misnomer gives the impression that black molds are all bad, but any other kind of mold is okay.  I don’t know where this came from, but it just isn’t true.

Black mold (often, but not always, Stachybotrys chartarum) has many varieties that are, indeed, toxigenic.  But there are also varieties of black mold that are not.  Some black molds, like alternaria, are only allergenic- but not all of those molds are black.  And some types can pose almost no risk to human health at all.  Aspergillus is typically a green mold, and can be very toxic to human health.  But there are varieties of aspergillus that can present as brown or black as well.  Still, aspergillus can range in toxicity, color, and varying affects on human life.

The point is, there is no hard-and-fast way of telling mold type or toxicity based on it’s color or presentation.  And just because a mold is not toxigenic or allergenic does not make it harmless, either.  Consider that there are wood destroying types of fungus (pictured above from a recent project in Charlotte, NC) that can be extremely harmful to a home but have relatively inert effects on human health.  And according to some sources, wood destroying types of fungus account for more annual property loss than fires, floods and termites COMBINED.  So, in that way, they are not exactly harmless, are they?

We should also consider that many homeowner’s insurance policies have significant limitations on their coverages of mold, while some even outright exclude it.  This means a homeowner could be completely on their own with structural repairs caused by such damage, and the damage can be significant.  Know that wood destroying fungi can accelerate wood damage by 200 times on a structure depending on the type of mold and species of lumber, so it can become a major problem very quickly.

There are simply too many variables to predict mold damage or toxicity based on color, amount of visible biofilm, or type of material (lumber) present.  We can’t do it.  The most important thing to know when dealing with any mold is that it cannot survive or proliferate on a surface without 3 basic things: organic food source, oxygen and moisture.

So if you limit or eliminate one of those three things, you can stop mold- any mold- from ever becoming a problem in the first place.

Our goal is to stop mold by creating an environment that it cannot thrive in.  Typically, we remove the moisture. We usually can’t remove the food source because lumber is needed for our building construction, and we can’t eliminate oxygen because this is still the Earth and oxygen is everywhere. But what we can do is to prevent moisture absorption into lumber by maintaining a constant wood moisture value of less than 18%.  In doing this, we will create an environment that mold cannot thrive in.  This is what we want and need for our homes.

Consider what mold can be doing to you, your family, AND your biggest investment even if (and sometimes especially if) you can’t see it.  There is so much at stake when it comes to mold and moisture in our homes.  If you see or suspect that you might have a problem, call Intellivent today.