“Black mold” is the name most people use for Stachybotrys chartarum, a greenish-black mold that grows on materials that stay wet for a long time. It has a scary reputation, and while some of that is overstated, black mold is a sign of a serious, ongoing moisture problem that should never be ignored.
What Does Black Mold Look Like?
- Dark green to black in color
- Slimy or wet-looking when active, sooty or powdery when dry
- Often grows in circular, spotty patches
- Accompanied by a strong musty, earthy odor
Keep in mind that many molds are black or dark green, including Cladosporium, Aspergillus and Alternaria. You cannot confirm Stachybotrys by sight alone. See our guide to common types of mold.
Where Black Mold Grows
Stachybotrys needs constant moisture and cellulose to feed on. It rarely shows up after a quick spill. Instead it follows long-term problems such as:
- Slow plumbing leaks inside walls or under sinks
- Roof leaks that soak attic sheathing or ceiling drywall
- Flooded basements or crawl spaces that were not dried properly
- Water damage that was painted over or covered with new flooring
- Behind washing machines, dishwashers, refrigerators and water heaters
Black Mold Health Risks
Stachybotrys can produce compounds called mycotoxins. According to the CDC, however, there is no proven link between black mold specifically and rare conditions sometimes attributed to it, and the agency recommends treating all indoor mold the same way. What is well established is that exposure to mold of any type can cause:
- Nasal stuffiness, sneezing and runny nose
- Throat irritation and coughing or wheezing
- Eye and skin irritation
- Worsened asthma symptoms
- More serious lung infections in people with weakened immune systems
Infants, older adults, and anyone with asthma, allergies or a compromised immune system should avoid exposure. If you are experiencing symptoms, talk to your doctor.
Can I Remove Black Mold Myself?
For very small areas (under about 10 square feet) on hard surfaces, the EPA says homeowners can usually clean mold themselves using detergent and water, with an N95 respirator, gloves and goggles, and then dry the area completely.
You should call a professional mold remediation company if:
- The growth is larger than 10 square feet
- It is growing on drywall, insulation, carpet or other porous materials
- It is inside walls, ceilings, ductwork or crawl spaces
- It resulted from sewage or flood water
- You have health concerns about exposure
Why Disturbing Black Mold Can Make It Worse
Scrubbing, sanding or tearing out moldy drywall without containment can release millions of spores into the air and spread contamination to clean parts of the house. Professional remediation follows the IICRC S520 standard, which includes:
- Assessment: finding all affected areas and the moisture source.
- Containment: sealing the work area with plastic sheeting and negative air pressure.
- Air filtration: running HEPA air scrubbers to capture airborne spores.
- Removal: cutting out and bagging contaminated porous materials.
- Cleaning: HEPA-vacuuming and treating remaining surfaces with antimicrobials.
- Drying and moisture correction: fixing the leak and drying the structure so mold does not return.
- Verification: confirming the area is clean before rebuilding.
How to Prevent Black Mold
- Fix leaks immediately and dry wet materials within 24 to 48 hours
- Keep indoor humidity between 30 and 50 percent
- Run bathroom and kitchen exhaust fans
- Keep gutters clean and grade soil away from the foundation
- Have water damage professionally dried rather than waiting for it to air dry
Read more about how fast mold grows after water damage.
Black Mold FAQ
Is black mold more dangerous than other mold?
It is often treated as the most dangerous, but health agencies recommend treating all indoor mold growth as a problem to be removed, regardless of color or species.
Should I test for black mold?
If you can see mold, testing is usually not necessary before removal. Testing is useful when you smell mold but cannot find it, or for clearance after remediation.
Does homeowners insurance cover black mold?
Coverage usually depends on the cause. Mold resulting from a sudden, covered water loss may be covered, while mold from long-term leaks or humidity often is not. Check your policy and talk with your agent.
Need Help Now? Longview Restoration Is Available 24/7
Longview Restoration is a locally owned, IICRC-certified water, fire, mold and storm damage restoration company. Our technicians respond day or night, document everything for your insurance claim, and restore your property to preliminary condition.
- Call 24/7: (615) 903-0053
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- Learn more: Water damage restoration · Mold remediation