Cracked, Missing or Stained Grout
Isolated missing joints can be a maintenance issue. Repeated cracks along the same line can indicate movement underneath. Dark staining may be surface buildup or persistent moisture. The visible symptom should be understood before simply adding new grout.
Remove Enough Failed Material
New grout needs a clean joint depth to bond. Smearing fresh material over loose or contaminated grout often fails quickly. Tile edges should be protected during removal. New grout may differ in color from aged surrounding joints, so confirm the desired finish and matching expectations before the repair.
Corners and Changes of Plane
Many inside corners and tub/shower transitions are designed for flexible sealant rather than rigid grout. Use Caulking for flexible joint work where appropriate.
If tile itself is loose/cracked, use Tile Repair. Shower-system problems may route to Bathroom / Shower Waterproofing.
Call NJ-GoodHome at (223) 226-1828 with tile type, joint condition and any leak history.