What grout and caulk do
Grout fills the joints between tiles; caulk seals the joints where materials meet or move, such as the tub edge, inside corners and around the valve trim and spout. Neither is a full waterproof barrier, but together they keep most water on the tile surface and out of the wall.
When caulk shrinks away from the tub or grout cracks along a corner, water runs into the gap every shower. Over months that can soften drywall or backer board, loosen tile and stain the ceiling or floor nearby.
Look for these
- A gap you can slide a fingernail into between the tub and the first row of tile
- Cracked, crumbling or missing grout, especially in corners and near the floor
- Dark lines in grout that stay dark long after showering
- Caulk with mold underneath it, not just on the surface
- Tiles that move or sound hollow when tapped
- Open gaps around the valve trim plate or spout
Is resealing enough
- IfGaps are visible but tile is solid and the wall is firmThenCutting out and recaulking or regrouting is usually enough.
- IfTiles move or the wall feels soft when pressedThenThe backing behind the tile may be damaged; resealing alone won't fix it.
- IfWater appears below only when the tub is fullThenLook at the overflow gasket before resealing anything.
- IfWater appears even with the shower offThenThe leak is in the supply or valve, not the grout or caulk.
Doing a proper reseal
- Remove the old material.Cut out failed caulk completely and rake out loose grout. New caulk over old caulk doesn't bond well.
- Clean and dry.Clean off soap film and mildew and let the joints dry thoroughly, ideally a full day with the shower unused.
- Regrout first.Fill grout joints where needed and let them cure as the product directs.
- Caulk the change-of-plane joints.Use a bathroom-rated sealant at the tub edge, inside corners and around trim. Filling a tub with water first helps it settle before caulking the tub joint.
- Let it cure.Keep the shower dry for the cure time on the product before using it.
What to ask if someone else does it
- Will you cut out the old caulk and grout or go over it?
- What product will you use at the tub edge and corners?
- Did you check whether the wall behind the tile is still solid?
- How long should the shower stay unused afterward?
Common questions
How often should shower caulk be redone?
Whenever it pulls away, cracks or has mold under it. Hard-water deposits and cleaning both wear it down over time.
Do I need a plumber for regrouting?
Not necessarily; it is tile work. Call a plumber when testing points to the valve, drain, overflow or pan.
Will sealing the grout make it waterproof?
A grout sealer helps resist staining and absorption, but it isn't a waterproof layer. The waterproofing is behind the tile or under the floor.
General information for Fullerton, not a quote or professional advice. In an emergency, call 911.