How to Re-Caulk a Bathtub (Stop Water From Getting Into Your Walls)

Home Maintenance7 min readSeptember 28, 2026

Cracked or peeling caulk around your bathtub isn’t just cosmetic — every gap is a path for water to get behind your walls, and water behind walls means invisible mold and structural damage that shows up as someone else’s repair bill. Caulk is a flexible sealant that flexes as the tub shifts with weight and temperature, and over time that constant movement makes it crack or pull away. This is a $15 fix you can do in an afternoon.

What you need

White bathroom silicone caulk (not latex or painter’s caulk — silicone is waterproof and flexible), a caulk gun (~$12), a caulk removal tool or utility knife, painter’s tape, rubbing alcohol and a cloth, and a small bowl of water for smoothing.

Step 1: Remove all the old caulk

This is the step that determines whether the new caulk lasts, since new caulk won’t bond to old caulk. Cut along both edges with the removal tool or utility knife, lift it out, get into the corners, and scrape off any residue. Partial removal leads to failure within weeks.

Step 2: Clean and dry the surface

Clean both surfaces thoroughly with rubbing alcohol and let them dry completely — at least 15–20 minutes. Silicone needs a dry surface to bond; any moisture in the joint compromises the seal. Do this project when the bathroom hasn’t been used for a few hours.

Step 3: Apply painter’s tape

Tape both sides of the joint, leaving the gap exposed, and press it down firmly so nothing seeps underneath. This keeps your lines clean and straight.

Step 4: Apply the caulk

Cut the tube tip at a 45-degree angle to roughly match the gap width, load the gun, and hold it at a 45-degree angle to the joint. Run one continuous bead the entire length without stopping — too slow creates buildup, too fast creates gaps.

Step 5: Smooth the caulk

Wet your finger and run it along the bead in one smooth, continuous pass, applying light pressure to create a concave surface. One pass beats several — each additional pass can pull caulk back out of the joint.

Step 6: Remove the tape and let it cure

Pull the tape away at a 45-degree angle within 10–15 minutes, before the caulk skins over, or it’ll peel up with the tape. Let it cure a full 24 hours before using the shower — it skins quickly but needs a full day to cure through.

Mistakes to avoid

Not removing all the old caulk. Applying over old caulk guarantees early failure.
Caulking a surface with hidden moisture. Wait several hours after any water use.
Using the shower before it’s cured. Rushing this peels the seal away within weeks.

Remove the old caulk completely, clean and dry the surface, tape it off, run a continuous bead, smooth with a wet finger, and stay out of the shower for 24 hours. That’s a repair that lasts years and keeps water out of your walls.