Stachybotrys chartarum
The organism behind the 'black mold' headlines
What it tells you about the building
Stachybotrys is a late-succession organism: it requires cellulose and sustained, heavy moisture — typically weeks of saturation — to establish. Finding it is forensic evidence of a long-duration water event, not casual humidity. It produces sticky spores that do not aerosolize readily until the material dries or is disturbed, which is why demolition without containment is the classic distribution event.
Why it matters in assessments
It is one of the marker species weighted heavily in water-damage indices like HERTSMI-2, and among the species most discussed in the context of mycotoxin production in buildings. Its presence in dust testing at meaningful levels generally moves a building into the remediate-and-verify category for sensitized occupants.
What remediation requires
Source correction is mandatory since its presence proves a serious moisture history. Affected porous materials are removed under full containment with negative pressure — never dry-scraped or treated in place — followed by fine-particle cleaning and independent verification.
Dark greenish-black, often slimy when wet and sooty when dry, typically growing in patches with defined edges on paper-faced materials.
- Wet drywall paper facing
- Ceiling tiles after leaks
- Wallpaper and paper products
- Wood and cellulose materials with long-duration saturation
State editions
Where this species shows up depends on where local climate and housing stock meet its moisture requirement. Read the local picture:
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