Where Mold Hides in San Antonio Homes

Under kitchen and bathroom sinks is the first place to look. Supply valves seep. Disposal connections loosen. A drain can leak only when the basin is full. The cabinet floor may hide the evidence until it swells or the baseboard outside the cabinet changes color.

Use a flashlight and feel around the shutoff valves with a dry paper towel. A small recurring drip can keep particleboard and drywall damp without leaving a puddle. If the material smells musty or feels soft, stop the leak before cleaning the surface.

Behind washing machines is another common location. Washer hoses, drain standpipes and supply boxes sit out of sight. After the 2021 and 2023 freezes, we opened walls across San Antonio where burst or cracked lines had soaked insulation and drywall behind appliances.

The AC plenum and drain pan deserve attention because the system runs almost nonstop during a humid summer. Condensation is normal. Standing water, wet insulation and repeated drain backups are not.

A musty smell when the system starts can come from the plenum, coil area or nearby wet building material. Dust on a damp porous liner creates conditions where growth can develop. HVAC plenum cleaning may remove buildup, but a leak or drainage problem has to be repaired or the condition returns.

Do not spray household cleaner into the equipment. Turn the system off if water is near electrical components and call the appropriate HVAC professional. If suspected mold extends into building materials, arrange a mold inspection.

At slab level, baseboards often tell the story first. A dark line, peeling paint, swollen trim or flooring that lifts along one wall can point to a plumbing leak, exterior water entry or moisture moving from an adjacent room.

San Antonio has many slab-foundation homes. A supply or drain problem below or within the slab may appear far from the source. Drying the visible floor does not prove the wall cavity is dry. We use moisture readings and, when needed, open a controlled area to inspect what is behind the finish.

Water heater closets create similar hidden damage. A relief valve, pan drain or connection can leak slowly. The closet may stay warm, dark and poorly ventilated, so the lower drywall and platform should be checked whenever the heater is serviced.

Attic decking and roof penetrations are vulnerable after wind-driven rain. Flashing around vents, chimneys and roof transitions can admit a small amount of water that never reaches the living-room floor. Wet insulation may hold it against the decking.

Hill Country limestone exteriors can complicate tracing because water may enter at a roof or wall detail and travel before it shows indoors. Brown ceiling staining, compressed insulation or rusted fasteners help narrow the path.

Finding suspected growth does not tell you how far it extends or why it started. Texas requires licensed professionals for regulated mold work over the state threshold. Fresh Air holds TDLR company license #RCO0176 and contractor license #MRC0212. Our mold remediation work focuses on containment, removal and correcting the moisture conditions behind the damage.

A flashlight check twice a year can prevent surprises. Look below sinks, around washer connections and at the water heater pan. Check the AC drain before summer and scan attic decking after a hard storm. You are looking for a change: fresh staining, swelling, dampness or a new odor.

If you find one, photograph it before moving material. Do not close wet cabinets or stack belongings against a damp wall. Stop the source if it is safe, then get the hidden side checked. Early access is usually simpler than opening a larger area after finishes begin to fail.