Types of Mold Found in Homes
Black, white, green — and the species behind them. What each looks like, where it grows, and which deserve concern.
Common types
- Stachybotrys (black mold) — dark green/black and slimy, on chronically wet drywall and wood. Highest concern.
- Aspergillus — green, white, or yellow, on walls, insulation, and HVAC. Moderate to high.
- Penicillium — blue-green and fuzzy, on water-damaged materials. Moderate.
- Cladosporium — olive to brown/black, in bathrooms, fabrics, and ducts. Moderate.
- Alternaria — dark green/brown and velvety, around showers and sinks. Allergenic.
Color isn't the whole story
"Black mold" is an appearance, not a species — many dark molds are harmless and some dangerous ones aren't black. To be sure, a lab test settles it.
What they share
Every type needs moisture. Whatever the species, the fix is the same: safe removal plus eliminating the water source — our process.
FAQ
Types questions
Cladosporium, Aspergillus, Penicillium, Alternaria, and Stachybotrys (toxic black mold). They differ in color and risk.
Stachybotrys and some Aspergillus species are the bigger health concerns, but any mold can trigger allergy or respiratory symptoms and signals moisture.
No — color is a clue, not a verdict. Many species share colors; only lab testing confirms which one you have.
Boulder Mold Guides
More mold resources
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