Grout, a cement-based product, fills the seams between the tile in a shower. A grout crack allows moisture to seep into the recesses behind the shower's tile. After the moisture passes the grout, it soaks into the shower's backing material and eventually turns into mildew. Pressing caulk into the crack temporally seals the grout. However, over time the caulking peels and traps moisture against the grout, causing black-colored mold. Removing the damaged grout and regrouting the shower solves the problem permanently.
Clean the shower tile, using an all-purpose cleaner and rag. Remove all soap scum from the shower tile.
Remove the shower drain cover and the faucet fixtures, using the correct screwdriver to remove the retaining screws. Stuff a rag into the top of the shower drain's hole. Keep the rag near the drain's surface.
Remove the caulking from the shower tile grout, using a utility knife. Run the knife's blade on each side of the caulking joint and peel the caulking off the grout.
Put on safety glasses and a dust mask.
Cut out the center of all grout joints in the shower using an oscillating tool with a grout removal blade, or a rotary tool with a grout removal attachment and grout removal bit. Work the bit or blade across the entire length of each joint until it hits the shower's backing material, keeping the bit or blade in the center of the grout joint.
Remove any grout that remains attached to the sides of the tile, using the utility knife for leverage. Hold the knife's blade on the seam between the grout and the tile. Press down on the grout with the knife. The grout will snap off the tile's edge, moving toward the groove cut in the center of the grout joint.
Remove all of the old grout debris, using a vacuum. Suck all of the debris from the grout joints, then clean the tiles' surface.
Mix grout and water in a bucket, using a margin trowel to stir the mixture. If the grout joints measure more than 1/8 inch across, use sanded grout. If the grout joints measure less than 1/8 inch across, use unsanded grout. Follow the grout manufacturer's recommended powdered-grout-to-water ratio. Mix the grout in the bucket until the grout has a pasty consistency.
Press the grout into the shower's grout joints, using a grout float to apply the grout. Hold the grout float at a 45-degree angle to the shower tile. Fill the grout joints completely, forcing the grout mixture into the joint until it reaches the tile's backing material.
Wait until the grout starts to form a skin on the tile's surface. This usually takes fewer than 10 minutes.
Wipe the shower tile's surface with a sponge, using circular motions. Remove all of the excess grout from the shower.
Wait until the grout forms a haze forms on the tile's surface. This usually takes 10 minutes.
Clean the shower tile with a clean sponge, wiping the tile in straight motions. Run the sponge across each grout joint at a 45-degree angle to the joint. Clean the sponge in water after each pass.
Let the shower tile grout dry for 24 hours. Polish the tile's surface with either a clean rag or a whisk broom.
Pull the rag from the shower drain. Replace the drain cover and the shower's faucet fixtures.
Things You'll Need:
- All-purpose cleaner
- Screwdriver set
- Utility knife
- Safety glasses
- Dust mask
- Rotary tool with grout removal attachment
- Oscillating tool
- Grout removal bit or blade
- Margin trowel
- Grout float
- Whisk broom
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