How to Recaulk a Bathtub

Cracked, moldy, or peeling caulk around a tub isn’t just unsightly. It lets water seep behind the wall, where it can cause rot and hidden mold. Recaulking is a cheap afternoon project, and the secret to a professional-looking line is careful prep.

What You’ll Need

• Caulk removal tool or plastic putty knife
• Utility knife
• Rubbing alcohol and clean rags
• Painter’s tape
• 100% silicone or siliconized kitchen-and-bath caulk labeled mold-resistant
• Caulk gun
• A caulk smoothing tool or a small cup of soapy water

Strip Out the Old Caulk

1. Score along both edges of the old bead with the utility knife, holding the blade low so you don’t scratch the tub or tile.
2. Pull out and scrape away the caulk with the removal tool. A plastic scraper is safer on acrylic and fiberglass tubs.
3. For stubborn residue, a commercial caulk softener can help. Follow the label directions and keep the room ventilated.
4. If you find mold in the joint, treat it with a bathroom mold cleaner and rinse well.
5. Wipe the joint with rubbing alcohol to remove soap scum and leftover silicone film, which new caulk won’t bond to.

Let the area dry completely, ideally overnight. Caulk applied over moisture is likely to peel or fail early. Run a fan or open a window to help the joint dry faster, and avoid using the tub or shower in the meantime.

Apply a Fresh Bead

Fill the tub with water before you start. The added weight pulls the tub down slightly, so the caulk cures at the widest gap and is less likely to crack later when someone steps in.

1. Run painter’s tape along both sides of the joint, leaving a gap about the width of the bead you want.
2. Cut the caulk nozzle at a 45-degree angle with a small opening. You can always trim more.
3. Hold the gun at a steady angle and push a continuous bead along the joint, moving at an even pace.
4. Smooth the bead in one pass with a damp fingertip or smoothing tool.
5. Pull the tape off right away while the caulk is still wet, peeling it away from the bead at an angle.

Give It Time to Cure

Check the cure time printed on the tube. Many silicone caulks need a full day before they can get wet. Keep the bathroom ventilated, leave the water in the tub until the caulk has set, and hold off on showering until the recommended time has passed. Then drain the tub and check the bead for any thin spots or gaps you might have missed.

Tips for Lasting Results

• Work in short sections around corners so the caulk doesn’t skin over before you smooth it.
• Choose silicone for flexibility and water resistance, but remember that paint won’t stick to it.
• Run the exhaust fan or crack a window after showers to slow mold regrowth.
• Inspect the caulk once a year and seal small gaps before water gets behind them.