Bathroom mold, explained
When Bathroom Mold Is More Than a Cleaning Problem
Bathroom calls split into two groups. Surface mold on grout and caulk lives on soap film and shower spray, and it scrubs off. 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. When the growth is inside the bead, no spray will reach it; the old silicone gets sliced out with a razor, the gap is dried and treated, and new caulk goes 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.
In a lot of older baths, the tile was set over standard paper-faced drywall instead of cement board, and that facing feeds mold as soon as moisture reaches it. That's why Bathroom Mold Removal in Lexington so often involves a plumber and a remediator working the same job.