Is black mold common in Florida?

What black mold actually means

Black mold is a nickname, not a scientific category. It usually refers to Stachybotrys chartarum, which the CDC describes as a greenish-black mold that grows on materials high in cellulose, such as gypsum board, fiberboard and paper, and that needs constant moisture from water damage, leaks, condensation or flooding.

Plenty of other molds are dark too. The CDC’s position is that color isn’t a measure of danger, that it isn’t necessary to identify the type of mold growing in a building, and that all molds should be treated the same when it comes to health risk and removal. For the biology, see our page on what Stachybotrys is.

Why it turns up in Southwest Florida

Stachybotrys is slow compared with many common molds, and it needs materials that stay wet, not just humid. Southwest Florida homes create those conditions in a few predictable ways:

• Flood and surge water that soaked the lower drywall in Hurricane Ian, Helene or Milton, especially where walls were closed before they dried.
• An AC closet where a clogged condensate line or rusted drain pan has wet the drywall for months.
• Slow leaks under kitchen and bathroom sinks and behind washing machines and water heaters.
• Roof leaks that soak a drywall ceiling in the rainy season.
• Drywall on exterior block walls that stays damp from wind-driven rain or condensation.

Notice that most of these are hidden. The most concerning growth is often on the back of the drywall, not the side you see.

The dark spots you see more often

The black specks on AC supply vents, shower grout, window sills and bathroom ceilings are common in Florida and usually come from condensation or surface moisture. They may be mold, dust or a mix of both, and they’re not automatically Stachybotrys. They are a sign of moisture worth fixing. Our page on mold on window sills covers that situation.

Why mycotoxins matter more than color

Stachybotrys can produce trichothecenes, a group of mycotoxins, and other molds common in water-damaged buildings make their own. Mycotoxins can remain in dust and materials after the mold is dead, which is why killing mold isn’t the same as removing it. Our guide to black mold vs. mycotoxins explains the difference.

How to find out what you have

Only lab analysis can identify a mold. Depending on the situation, that can mean surface samples of visible growth, air samples, settled dust testing, or a mycotoxin panel on dust. In Florida, testing and clearance are handled by a licensed mold assessor who is independent of the company doing the removal, as Florida Statute 468.8419 requires unless a certified Division I contractor is involved. The company testing your home has no reason to find more mold than is there, and the company removing it can’t grade its own work.

Small spot or bigger problem?

The EPA’s general guidance is that in most cases a homeowner can handle a moldy area of less than about 10 square feet, roughly a 3 foot by 3 foot patch, once the water problem is fixed. Florida’s licensing law also uses 10 square feet as the line for when mold assessment and remediation become licensed work. Dark growth on drywall is a different case: what you see on the surface is often a fraction of what’s on the back, especially after a leak or a flood. If the stain keeps coming back, sits on an exterior wall or near the AC closet, or the house has storm history, get it assessed before you start cutting.

What not to do

• Don’t scrape or dry-brush it. That puts spores and fragments into the air.
• Don’t rely on bleach for drywall. Our page on bleach and drywall mold explains why.
• Don’t paint over it. The growth and the moisture stay behind the paint.
• Don’t run a fan across it to dry it out.

How it’s removed

Whether it’s Stachybotrys or another mold, the approach is the same: fix the water, contain the area, remove the porous materials that grew mold, HEPA-clean what’s left, treat for mycotoxins, and confirm with independent clearance testing. Our black mold removal service in Southwest Florida follows that process, and it’s backed by a complete-removal guarantee. We don’t close a job on a failed result.

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