Stachybotrys chartarum — commonly called black mold — is a dark-green to black mold species that grows on cellulose-rich materials (drywall paper, wood, ceiling tiles) that have been wet for an extended period, typically more than 48–72 hours. It is one of the species most associated with toxic mold exposure, though any mold at elevated indoor concentrations poses a health risk.
Because Stachybotrys spores are heavy and sticky, they do not disperse as readily as Cladosporium or Penicillium — which means air sampling alone may miss an active Stachybotrys colony. A licensed mold assessor will collect surface samples (tape-lift or swab) from any dark, slimy, or visually distinctive mold growth and send them to an AIHA laboratory for species confirmation.
Black mold removal follows the full IICRC S520 Level III remediation process: complete containment with negative air pressure, physical removal of all affected porous materials, treatment of structural surfaces, and independent clearance testing. There is no spray treatment that safely 'kills' Stachybotrys in place — the dead mold is still allergenic and the mycotoxins remain on the substrate. Physical removal is the only compliant approach.
Signs you need black mold removal
- Dark green, black, or greenish-black colonies on drywall, wood, or ceiling tiles
- Mold with a slimy or wet-looking surface texture (unlike dry, powdery Cladosporium)
- Musty or damp earthy odour in a basement, bathroom, or behind walls
- Mold growth in areas with a history of prolonged water exposure or chronic leaks
- Laboratory results identifying Stachybotrys on air or surface samples
- Health symptoms improving when leaving the property and returning when inside
Why Baltimore properties see this
Baltimore basement Stachybotrys cases are common in properties with chronic foundation seepage — the extended moisture exposure on wood framing and drywall creates ideal conditions for Stachybotrys growth over months or years.
New Jersey properties affected by Hurricane Sandy flooding in 2012 that were not professionally dried and remediated at the time may have latent Stachybotrys in structural framing that remained wet for weeks.
Miami properties with chronic HVAC condensation overflow — a very common failure mode in the tropical climate — frequently develop Stachybotrys on the drywall adjacent to the air handler closet.