Bathroom mold, explained
When Bathroom Mold Is More Than a Cleaning Problem
Every bathroom mold call falls into one of two buckets. Some of it is surface growth on grout lines and caulk, feeding on body oils and soap scum, and a good cleaning handles it. The other kind grows behind the tile, inside the wall cavity or under the floor, where a failed shower pan, a leaking valve or a bad wax ring keeps the framing wet for months.
Silicone caulk is a common trap. Once mold roots into the silicone itself, bleach only lightens the color for a few weeks, so the bead has to be cut out, the joint dried and cleaned, and fresh mildew-resistant silicone laid in. Overhead, the ceiling above the shower collects condensation when the fan is too small, gets shut off right away, or blows into the attic rather than through an exterior cap.
Older tub surrounds often hide paper-faced drywall behind the tile, and paper is mold food once water gets past the grout. That's why Bathroom Mold Removal in Maywood Park so often involves a plumber and a remediator working the same job.