Caulk replacement is the process of stripping away old, peeling, or moldy sealant and installing a fresh, highly flexible waterproof barrier along structural joints. Caulk is applied wherever tiles meet a different plane or material—such as corners, baseboards, and the edges of tubs, showers, counters, and sinks. Unlike rigid grout, caulk expands and contracts with structural shifting. When caulk dries out, splits, or traps deep black mold underneath its surface, it fails as a water barrier. Professional replacement includes complete removal, deep sanitization of the joint, and the application of a smooth, commercial-grade, mold-resistant sealant line.