Black mold removal, without the panic

Black mold removal, explained

What people mean by “black mold”

Black mold isn’t a scientific category. It’s a nickname, and most of the time it refers to Stachybotrys chartarum, a greenish-black mold that grows on water-damaged building materials. The trouble is that plenty of other molds are dark too. When we sample a black stain, the lab result is just as likely to come back as one of these:

Mold	Typical appearance	Where it tends to grow
Stachybotrys chartarum	Greenish-black, slimy when wet, sooty when dry	Drywall paper, ceiling tile, cardboard and other cellulose that stayed wet a long time
Cladosporium	Olive green to black, often speckled	Window frames, bathroom surfaces, the back of cool exterior walls
Alternaria	Dark gray to black, fuzzy	Showers, window sills, damp carpet
Aspergillus niger	Black with a powdery texture	Damp surfaces, dust and HVAC components

The distinction matters. A few spots of Cladosporium on a bathroom window frame is a cleaning job. Stachybotrys growing across the back of a drywall panel is a sign that water has been sitting in that wall for a long time, and it calls for removal under containment. The only way to know which one you have is to sample it.

Why Stachybotrys points to a long-term leak

Many molds will grow on a surface that is merely damp. Stachybotrys is fussier. It needs a food source rich in cellulose and a lot of water for an extended period, which is why it shows up behind leaking toilets and dishwashers, under sinks with slow drips, on the back side of drywall below a failed window, and in basements that flood repeatedly. Finding it tells you something useful: there is, or was, a persistent moisture problem nearby. Removing the growth without finding that problem only resets the clock.

What to do if you find it

• Leave it alone. Scraping, scrubbing or pulling at damp drywall releases spores and fragments into the air.
• Skip the bleach. It won’t reach growth inside the paper, and it changes what a sample will show. Our answer on whether bleach kills mold on drywall explains why.
• Stop the water if you can. Shut off a leaking supply line or fixture.
• Close the room off. Shut the door and keep children and pets out.
• Take photos. They help with insurance and with planning the work.

Why it usually has to be cut out

Drywall is a gypsum core wrapped in paper, and the paper is exactly what Stachybotrys feeds on. By the time you can see growth on the face of a wall, it has typically grown through the paper and often across the back side facing the cavity. No cleaner reaches that. The affected section is cut out past the visible edge, until moisture readings and inspection show clean, dry material, and the pieces are bagged inside containment before they’re carried through the house. Solid wood framing behind it is a different story: surface growth on studs can usually be HEPA vacuumed, wiped and treated rather than replaced.

The mycotoxin question

Stachybotrys is known for producing trichothecenes, a group of mycotoxins that stay behind after the mold is dead. That’s the main reason we don’t treat black mold removal as finished when the wall is replaced. Fine dust from the work area gets HEPA cleaned, exposed framing is treated with plant-based enzyme products designed to break down mold and mycotoxins, and we test settled dust for toxins when the situation calls for it. We use products from US Enzyme for that step. Read more about trichothecenes and the difference between black mold and mycotoxins.

In Indiana? See black mold removal in Indiana.

We remove mold and mycotoxins from buildings. We don’t diagnose or treat medical conditions. If you or anyone in your home has symptoms, please work with a doctor. With your permission, we’re glad to share test results and our plan with them.