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How to recaulk a bathtub

Cracked, moldy caulk lets water into the wall behind your tub. Fresh caulk takes an afternoon to apply, and the prep work is what makes it last.

Updated · 7 min read

  • DifficultyEasy
  • Time1–2 hours, plus curing time
  • If you need helpHandyman

The caulk where your tub meets the wall has one job: keep water out of the gap. Over time it cracks, peels away, or grows black mildew that will not scrub off. Once that happens, water can seep behind the tub and into the wall or floor, where it causes rot and mold you cannot see.

Recaulking is a job almost anyone can do. It is not hard, just a little fussy. The secret is in the prep: every bit of old caulk out, the joint clean, and the surface completely dry before the new bead goes on.

Plan on one to two hours of work, then time for the caulk to cure before anyone showers. Doing it in the evening, after the last shower of the day, works well.

What you'll need

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Most of these belong in a basic home toolkit.

Pick the right caulk

Look for a tube labeled for kitchen and bath use with mildew resistance. The two common types:

TypeGood forKeep in mind
100% siliconeWet joints that move, like tub-to-wall seams. Stays flexible.Can be harder to smooth neatly, so work quickly. Check the label for cleanup.
Siliconized acrylic (sometimes sold as "siliconized" sealant)Many people find it easier to work with. DAP recommends a siliconized sealant for tubs.GE warns that plain acrylic caulk can shrink and crack in wet areas, so choose one made for kitchen and bath.

If you plan to paint over the caulk line, check that the label says it is paintable.

Remove the old caulk

  1. Clean the tub first. Scrub away soap scum so you can see the edges of the old caulk.
  2. Soften it if needed. Hard or thick caulk comes out easier if you apply caulk remover gel and wait the time listed on the label.
  3. Cut and pull. Slice along both edges of the bead with a remover tool or utility knife, then peel or scrape it out. Hold blades low and gentle on acrylic or fiberglass.
  4. Get every last bit. GE notes that leftover fragments weaken the new seal. Scrape off the thin film too.

Clean off mildew and dry the joint

  1. Clean the joint. Use a bathroom cleaner or mildew remover according to its label, then rinse.
  2. Wipe with alcohol. Rubbing alcohol removes soap film and residue so the new caulk can stick. GE recommends it for this step.
  3. Let it dry completely. This is the step people rush. Moisture under fresh caulk is the main reason it fails to stick. Give it several hours, or overnight, with the fan running. Check the back corner and the gap itself, not just the surface.

Apply the new caulk

  1. Tape the lines. Run painter's tape along the tub and the wall, about 1/8 inch from each side of the joint, as GE suggests. Press it down firmly.
  2. Cut the tip. Snip the nozzle at an angle, starting with a small opening. You can always cut it bigger.
  3. Lay the bead. Hold the gun at about a 45-degree angle and push a steady, even bead into the joint. DAP suggests starting at a corner and working toward the middle, then doing the other side and meeting in the middle.
  4. Smooth it right away. Run a smoothing tool or gloved fingertip along the bead in one pass before it starts to skin over.
  5. Pull the tape. Remove the tape while the caulk is still wet, pulling it away from the joint. You will get a crisp, straight line.

Let it cure

Every product has its own times, so read the tube. As examples, GE lists some of its kitchen and bath silicone as water-ready in 30 minutes but advises leaving it alone for 24 hours for a full cure, and DAP lists one siliconized sealant as water-ready in four hours. When in doubt, wait longer. Keep the bathroom ventilated while it cures.

When to call a pro

Stop and call for help if:

  • The wall or tile around the tub is soft, loose or crumbling.
  • You see water stains on the ceiling below the bathroom.
  • Mold keeps coming back inside the wall or under the tile, or covers a large area.
  • The gap is wider than a caulk bead can fill, or the tub moves when you step in.
  • Grout is missing or cracked over a large area.

Renters, ask your landlord before starting. Leaks into the wall are usually their responsibility. A handyman can recaulk and regrout, and a plumber can check for leaks behind the wall. Not sure? Try the fix-or-call quiz.

Keep it from happening again

  • Run the fan or open a window during and after every shower.
  • Wipe the caulk line dry, especially in the corners and along the tub base.
  • Look over the caulk once a year for cracks, peeling or lifting.
  • Recaulk about a year after moving into a newly built home, since DAP notes houses settle, and plan on roughly every five years after that.

Common questions

Can I put new caulk over old caulk?

It is not a good idea. New caulk does not bond well to old caulk, and any mold or water trapped underneath stays there. Take the old bead out completely, clean the joint and let it dry first.

How long before I can shower after caulking?

It depends on the product. Some silicones are water-ready in about 30 minutes and some siliconized caulks in a few hours, but makers often advise waiting longer for a full cure. Follow the label on your tube.

Which is better for a tub, silicone or siliconized acrylic?

For a wet joint that moves, like the seam between a tub and the wall, 100% silicone is the usual choice because it stays flexible. Siliconized acrylic is easier to smooth and clean up. Pick one labeled for kitchen and bath use either way.

How often should a tub be recaulked?

Whenever the caulk cracks, peels, pulls away or stays stained after cleaning. DAP suggests checking about a year after moving into a new home, since houses settle, and roughly every five years after that.

Sources

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