"Black mold" is not a scientific category. It is what people say when they find something dark growing on drywall, on a bathroom ceiling, or behind a baseboard, and it covers dozens of species. The one that gives the phrase its reputation is Stachybotrys chartarum, which is genuinely less common than the internet suggests and which needs sustained wetting to grow at all.
The far more common finds in a Brazos County home are Cladosporium, Aspergillus and Penicillium. Several of those look black or near-black on a wall. Species identification rarely changes the work: containment, removal, cleaning and drying are the same regardless, and the remediation standard does not have a separate protocol for Stachybotrys.
What does change the work is the size of the affected area, the material it is growing on, and where the water came from.
The 25 square foot line, and why it matters here
Texas is one of a small number of states that licenses mold work. The Texas Department of Licensing and Regulation administers it, and the threshold is 25 contiguous square feet. Below that, a property owner or a general contractor may handle it. At or above it, the work has to be performed by a licensed Mold Remediation Contractor, and the assessment written by a separate licensed Mold Assessment Consultant.
Twenty-five square feet is a patch about five feet by five feet. A bathroom ceiling after a slow shower leak often exceeds it. A wall cavity behind a burst supply line almost always does.
There is a reason to care beyond compliance. When the job is done under license, you get a Certificate of Mold Damage Remediation, a Texas-specific document. It matters at resale, because Texas requires sellers to disclose known mold damage, and a certificate showing the work was done properly closes that conversation instead of opening it.
Finding the water first
Mold is the symptom. Water is the disease, and remediation that skips the water is remediation you will pay for twice.
In College Station and Bryan, the moisture sources we find most often are these.
Air conditioning condensate. The single most common cause here. Nine months of the year the AC runs hard, and a blocked condensate line, a rusted drain pan or an overwhelmed secondary pan puts water into a ceiling or a closet wall. Because the unit keeps running, the wetting is continuous rather than a one-off event, which is exactly what mold needs.
Under-insulated ductwork. Ducts running through a hot attic in July carry air at 55°F through air at 130°F. Where the insulation has slumped or the vapor barrier has torn, the duct sweats and drips onto the ceiling below.
Plumbing behind walls. Slow leaks at shower valves, toilet supply lines and dishwasher connections. These are the ones found late, because nothing shows until the drywall stains.
Roof and flashing. Brazos Valley storms bring wind-driven rain that gets under flashing and around penetrations. The stain appears several feet from the actual entry point, which is why probing matters.
Slab-related moisture. Most homes here are slab-on-grade. Where the slab was poured without a vapor retarder, or where the retarder was punctured, moisture moves up through the concrete and into wall plates and flooring. Older Bryan homes on pier and beam have the opposite problem: a damp crawl space venting into the floor system.
How the remediation is actually done
The work follows the IICRC S520 standard, which is the reference document for the industry.
Containment
The affected area is sealed off with polyethylene sheeting and a zippered entry. On a bathroom that may be a single-room containment; on a whole wall it may be a section of the house. HVAC supply and return in the containment area are sealed so that spores are not distributed through the ductwork.
Negative pressure
An air filtration device with HEPA media exhausts to the outside, holding the containment at slightly lower pressure than the surrounding rooms. Air flows in, not out. This is the step that separates remediation from cleaning, and it is the one most often skipped by people quoting cheap.
Removal
Porous materials that are visibly colonized come out: drywall, insulation, carpet pad, ceiling tile, MDF trim. They cannot be reliably cleaned, because the growth extends into the material rather than sitting on it. Cut lines are set well past the visible edge, because visible growth is smaller than actual growth.
Semi-porous and non-porous materials — framing lumber, concrete, metal, glazed tile — are cleaned rather than removed. HEPA vacuuming, damp wiping and, where the surface is rough sawn framing, abrasive methods such as soda or media blasting.
Drying
The structure is dried to a documented moisture content before anything is closed up. Pin and pinless meters on wood and drywall, thermo-hygrometers logging the ambient conditions, and dehumidification sized to the space. Sealing wet framing behind new drywall is how a job comes back.
Clearance
Post-remediation verification is a visual inspection plus air sampling, compared against an outdoor control. On a licensed job the assessor who wrote the protocol performs this, and they are required to be independent of the remediation contractor. That independence is a feature, not a formality.
What we will tell you honestly
Some of the calls we get do not need remediation.
Surface growth on grout, on a window sill, on the rubber gasket of a front-loading washing machine — that is a cleaning and ventilation problem, not a remediation job. We will tell you so, and tell you what to change, rather than sell you containment for a patch you could handle yourself.
Equally, we will tell you when what looks like a small patch is not. Two square feet of staining on a ceiling under an AC unit that has been leaking for a season is rarely two square feet of growth once the drywall comes down.
Health, stated accurately
Indoor mold exposure is associated with respiratory symptoms, worsening of asthma, and allergic response, and people with compromised immune systems face higher risk. That much is well established.
Claims that a particular species causes a specific list of severe illnesses go well beyond the evidence, and you should be skeptical of anyone who leads a sales conversation with them. Removing the mold and fixing the moisture is the right thing to do because damp buildings are bad for buildings and for the people in them, not because of a diagnosis somebody made from a photograph.
If you are looking for testing before deciding, see mold inspection and mold testing. If the growth followed a leak or a burst line, water damage restoration covers the drying side.
Common questions
Do I need to know the species before you start?
No. Identification rarely changes the protocol, and the remediation standard has no separate procedure for Stachybotrys. Extent and moisture source drive the work.
Can I just spray bleach on it?
On a hard non-porous surface like tile, that removes the staining. On drywall it does not, because the growth is inside the material and bleach is mostly water, which is what caused the problem. It also does nothing about the leak.
What does the 25 square foot rule mean for me?
Below that area, you or a general contractor can handle it. At or above, Texas requires a licensed remediation contractor and a separate licensed assessor. That separation exists so the person checking the work is not the person paid for it.
Will my homeowners policy pay for it?
Sometimes, and it depends heavily on the water source. Texas policies commonly limit mold coverage, and a sudden burst pipe is treated very differently from a long-term leak. We document the source and the timeline, which is what the adjuster will ask for.
How long will we be out of the house?
Most single-room jobs run two to four days including drying and clearance. You can usually stay in the house, because the containment is sealed and under negative pressure, though we will say otherwise if the affected area includes the only bathroom or the HVAC has to come down.
Do you do the repairs afterwards?
Yes, once clearance passes. See mold damage repair. Putting drywall back before clearance is how you end up doing it twice.
Get a free assessment
Tell us what you are seeing and where. We come out, find the moisture source, and put the scope and the price in writing before anything is torn out.