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.





New home construction and mold?

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This is something we have seen more and more in recent years in the Charlotte area- mold formation in the crawlspaces of brand new homes. We are literally seeing it before the rough plumbing and electrical are completed in some cases. But why?

The main contributor in today’s residential construction relates to our current building techniques. Our homes are built air tight (or close to it). Tongue and groove subfloors, home wraps, foam sealants, dual-pane windows, insulated doors and vapor-taped exterior seals on openings are creating environments that do not allow free-moisture exchange via, what is known as, the “stack effect”.  If the vapor cannot ventilate vertically through the home, it becomes trapped in lower areas like the crawlspace or basement; raising wood moisture and humidity levels.  This can rapidly lead to fungal growth on the organic substrate.

While this “tightening” of the construction of our homes serves to benefit us in energy savings and comfort down the road, these methods do us few favors in terms of providing for fresh air exchange with the outside in the short-term, which can be vital in drying out a crawlspace to prevent mold spore proliferation in the first place.

If you’ve had the unpleasant privilege of dealing with a mold remediation bill on a brand-new home, you will know what a frustrating and profit-consuming thing this can be. We have prevention services that can eliminate mold growth as a possibility, while providing a fully-transferrable warranty against mold growth in the property so that your buyers are getting piece-of-mind with their purchase.

And all of this can cost far less than you might think (certainly less than a mold remediation bill.)

We have seen many construction projects where this has occurred.  But, be assured, there are preventative measures that can be taken. We are in the business of providing these solutions to our customers, which include builders, renovators, investors, and real estate professionals alike.  We have a range of vapor retarding solutions, ventilation systems, dehumidification appliances and even sealants or coatings that can provide a complete mold-proofing barrier over the wood material, insuring that fungal proliferation will not occur.

Reach out to us at Intellivent to learn more about mold removal in Charlotte.  We are happy to help you make sure the first thing living in the new home you’re building is the person buying it and not mold.


Mold, Moisture, and Your Crawlspace

By Bill Mitchell
Originally written June 23, 2017

It was an unusually humid, warm, and very wet Spring in North Carolina. Now, officially two days into the Summer season, there’s very little sign of things letting up. It has rained in the Charlotte area every day for the last 10, and there have already been 3 “named” tropical storms. So, we’re off and running.

Make no mistake, all this wet weather makes for a potentially problematic environment for the traditionally vented crawlspace under your home.

The water table is at capacity in most areas. The ground is full- with so much precipitation, it’s literally holding all the water it can. This includes the ground beneath a home. As the soil releases this moisture away (in the form of evaporation), that moisture releasing into a crawlspace has nowhere to go. Damp air becomes trapped against the structural members of the dwelling and compressed into the crawlspace with no way of ventilating itself, raising humidity and causing wood moisture values to elevate. Once the moisture content of the wood gets to 20%, mold will form quite rapidly.

Compounding this problem is the presence of colder air in the crawlspace. A crawlspace will typically be a constant 65-75 degrees in summer. We all know that our outside temperatures in summer are much higher than this, and humidity values are consistently through the roof as well. Albeit under the roof, the crawlspace and it’s environment are still under constant attack from the elements. It’s a fight against nature all of the time.


This diagram illustrates the what happens in the crawlspace when we cool air that is 80% humidity just FIVE DEGREES! And, don’t think of this diagram as theoretical, it’s something that actually happens constantly beneath our homes.

(Another neat tool to see how a crawlspace is affected by humidity and temperature can be found here. You can see just how quickly mold can form in a space when temperature and dew point are not effectively managed.)

“So what do we need to do?”

At a minimum, a home needs a good vapor barrier. What’s a “good” vapor barrier? A .6mil poly plastic (we prefer .10mil) covering 100% of the crawlspace soils is a must. No matter what a salesperson or contractor will try to tell you, the thickness of the plastic is irrelevant in keeping out moisture. A product’s thickness is only important as it speaks to it’s durability. The thicker it is, the tougher it is and, therefore, will hold up better against wear over time.

A “good” vapor barrier should also be staked to the ground to prevent movement as you or workers crawl in and out of the crawlspace on the material. The seams should also overlap 6″-12″, where possible, to prevent unimpeded evaporation of ground moisture through these joints and into the space.

But, often, a “good” vapor barrier is nowhere near enough. And, ideologically, this is where we tend to part ways with some of our competitors in the industry. We don’t like to seal a space. Components of a crawlspace structure are meant to breathe. The house requires it.

We believe in controlled ventilation of the crawlspace using a proven, engineered system like Atmox. This system utilizes low-voltage fans (using far less energy than large dehumidification units that are essential in encapsulation systems) and a computer controller that measures dew points inside and outside of the home to decide when environmental conditions are favorable to import dry, healthy, and helpful air. Vents (and other penetrations or openings), not in use by the Atmox system, are sealed off completely, creating a tight space that keeps the free exchange of damp, humid air from outside the house to a bare minimum. This keeps the crawlspace structural components too dry for mold to form, and keeps the environment healthy and stable consistently over time.

As an added benefit, the import of fresh air into the space reduces or eliminates smells and odors associated with off-gassing encapsulation liners or musty odors from the trapped, stale air beneath the structure. Customers with sensitivities to these smells rave about the benefits of bringing fresh air into the house envelope. No more dirt smells. No more musty smells. No more “plasticky”, cat urine smell from the sealed liner.

So, with a “good” vapor barrier on the ground, a controlled ventilation system beneath the foundation of the home, and sealing up auxiliary vent openings and porous air leaks in the foundation, the Atmox is able to maintain the clean, dry, and stable environment that we need in our crawlspace. This adds value to the home and, best of all, can do so for less than half the cost of an encapsulation in a crawlspace.