Stachybotrys chartarum
The greenish-black mold behind the "black mold" name, which grows on wet high-cellulose materials like drywall, fiberboard, and paper.
The short version
- CDC describes Stachybotrys chartarum as a greenish-black mold.
- It grows on material with high cellulose content: fiberboard, gypsum board, and paper.
- It needs sustained moisture, from water damage, leaks, condensation, water infiltration, or flooding.
- CDC states that it and other molds may cause nonspecific health symptoms, and that all molds should be treated the same for removal.
- Its presence signals a persistent water problem, which is the finding that actually matters.
What it actually means
Stachybotrys chartarum is a real genus and species, and it is the organism people are usually thinking of when they say black mold. CDC describes it as a greenish-black mold that grows on material with a high cellulose content, such as fiberboard, gypsum board, and paper, when moisture is present from water damage, water leaks, condensation, water infiltration, or flooding.
The most useful thing about finding it is not the species name. It is what the species implies about the building. Stachybotrys needs sustained wetness on cellulose to establish, which means finding it is strong evidence of a chronic or repeated water problem rather than a one-off spill that dried on its own. In a remediation, that pushes the investigation toward roofs, plumbing in walls, chronic condensation, and building envelope failures.
On health, CDC is measured, and it is worth resisting the more dramatic claims made elsewhere. Its guidance is that Stachybotrys chartarum and other molds may cause nonspecific health symptoms, that any mold found in a building should be removed, and that all molds should be treated the same with respect to potential health risks and removal. The remediation does not change because of the name.
What it looks like on a real job
Where we find it, the scope is driven by the same things as any other growth: the moisture source, the extent of Condition 3 growth and the Condition 2 area around it, containment sized to the contamination, physical removal of affected porous materials, drying to a dry standard, and independent verification.
The one practical difference is investigative rather than procedural. Because it indicates sustained moisture on cellulose, we look harder for a long-running source, and we are more likely to recommend opening adjacent assemblies to check whether the growth extends further than the visible patch suggests.
Questions we get asked
- Is Stachybotrys toxic mold?
- The phrase overstates what the public health guidance supports. CDC’s position is that this and other molds may cause nonspecific symptoms, that any mold found should be removed, and that all molds should be treated the same for removal purposes. Treat it seriously and remove it properly, without the mythology.
- Does finding Stachybotrys change the remediation?
- Not the procedure. Containment, physical removal, drying, and verification are the same regardless of species. What it changes is how hard we look for a long-running moisture source, because this organism needs sustained wetness on cellulose to establish.
- Should I test to confirm it is Stachybotrys?
- For deciding whether to remediate, no. CDC states it is not necessary to determine what type of mold is growing. Testing earns its cost for finding hidden growth, defining the extent of contamination, and verifying a completed remediation.
Official sources
Everything on this page rests on the documents below. Read them yourself, they are all free.
- CDC, Facts About Stachybotrys chartarum
- CDC, Mold and Your Health
- ANSI/IICRC S520, Standard for Professional Mold Remediation
Last reviewed against these sources on August 26, 2026. These definitions are general information about restoration work and property claims in Florida, not legal advice or a coverage opinion. Your policy language and the facts of your loss control what is owed. Swift Response Restoration Inc is a licensed restoration contractor, not an insurer, a public adjuster, or a law firm.
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Related terms
Black Mold
A common name rather than a species, and one that misleads: CDC advises that all molds be treated the same way for removal regardless of type or color.
Fungal Growth
Mold actively growing on a material, which requires moisture, a food source, and time, and which is why remediation always starts with the water.
Mold Testing
Sampling to answer a specific question. Neither CDC nor EPA recommends routine testing to decide whether visible mold should be removed.
Mold Condition 1, 2, 3
The IICRC S520 grading of a space: Condition 3 is active growth, Condition 2 is settled spores from it, Condition 1 is a normal fungal ecology.