What it is
Chaetomium is a brown to olive-gray mold that breaks down cellulose-based materials - much like Stachybotrys. The presence of Chaetomium in a lab report is a strong indicator of long-term water damage.
Where it grows
Water-damaged drywall, wood, wallpaper backing, carpet padding. Almost always indicates extended moisture exposure.
Health impact
Produces mycotoxins. Can cause respiratory irritation, sinus issues, and stronger reactions in sensitive individuals.
This species produces mycotoxins. That matters because mycotoxins can affect indoor air quality even after visible mold is gone - they ride on dust particles and require thorough removal, not just surface cleaning.
Property risk
Actively breaks down cellulose substrate. Confirmed colonies usually mean the affected drywall, framing, or other cellulose material needs to come out.
When to test
If you see what looks like chaetomium in your home - or if a lab report flagged it in your air samples - testing the affected area against an outdoor baseline is the most useful next step. The decision about remediation depends on:
- How much is present (spore count per cubic meter, or visible square footage)
- What's beneath it (porous materials like drywall and insulation usually need removal; hard surfaces can often be cleaned)
- Whether the moisture source is identifiable and fixable
Our approach
For confirmed indoor chaetomium colonies, our process is the same as for any mold species: identify and stop the moisture source, contain the work area, remove what's compromised, HEPA-filter and HEPA-vacuum the surrounding area, dry everything, and verify with a post-remediation clearance test against the outdoor baseline.