The line where a tub meets tile gets a lot of attention because it is
easy to see. Water can also reach a wall at a shower door, a sink
backsplash, or the edge of a vanity. When a sealant joint separates, the
right fix starts with asking whether the surfaces underneath are sound
and dry.
Look for gaps, peeling, persistent dark staining, and soft or swollen
material nearby. Clean and dry the area as the sealant manufacturer
requires. Remove failed material rather than smearing fresh product over
an old bead. Choose a product suitable for that surface and wet
location. Some joints use grout, some use flexible sealant, and a shower
assembly may have intentional weep paths that must stay open.
If staining returns quickly, tile moves, the wall feels soft, or
water appears below the bathroom, ask a qualified plumber or
tile/waterproofing contractor to investigate. Caulk can’t repair a
failed shower pan, loose plumbing connection, or saturated backing. The
EPA’s moisture guide puts the focus on finding and fixing the water
source.
After the repair, run the exhaust fan and allow wet surfaces to dry.
A photo of the joint with a date can help you tell a new stain from an
old one. I keep local trade contacts on Helpful
Resources and household upkeep ideas on Homeowner
Tools & Supplies. Pick materials for the actual assembly, not
just the label on the tube.