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How do you recaulk a bathtub or shower?

Updated August 2026

45–60 minutes (plus a 24-hour cure) · Easy DIY

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A tub or shower recaulk is 45 to 60 minutes of work plus a 24-hour cure, and the order matters more than the skill. Cut out every trace of the old bead, kill the mildew and dry the joint, fill the tub with water so the gap sits at its widest, then lay one continuous pass of 100% silicone and tool it with a wet fingertip. A tube costs $6–10. Do it the week the bead cracks, peels, or grows black spots that will not scrub out, because that joint is the only thing holding shower water out of the framing behind the wall.

What you need

Before you start: Run the bathroom fan and open the door. Curing silicone gives off acetic-acid fumes, and bleach is worse: never mix a bleach spray with vinegar, ammonia, or a tile cleaner that contains either. Angle the knife blade away from acrylic and fiberglass tubs, which scratch far more easily than porcelain, and wear gloves, since uncured silicone does not come off skin without solvent. If the old bead hides soft, dark, spongy substrate, stop and open the wall: caulk over rot only buys time.

Steps

  1. Score both edges of the old bead with a fresh blade, one cut along the tile and one along the tub, keeping the knife flat so it does not gouge the finish.
  2. Peel the bead out in strips with a plastic removal tool, then scrape until no rubbery film is left. New silicone will not bond to old silicone, so anything you leave becomes next year's leak.
  3. Spray the bare joint with diluted bleach (roughly 3/4 cup per gallon of water), wait 10 minutes, and rinse. That kills the mildew living in the grout, not just the stain on top.
  4. Wipe the joint with rubbing alcohol and let it dry at least 1 hour with the fan running. A joint that feels dry but holds moisture will blister the new bead within a week.
  5. Fill the tub to just under the overflow (or stand in the shower pan) before you caulk. The weight drops the tub a fraction of an inch and opens the joint to its widest, so the cured bead will not tear later.
  6. Cut the nozzle at 45 degrees to a 1/8-inch opening, puncture the inner seal, and run one unbroken bead down the joint, pushing the gun ahead of the tip instead of dragging it.
  7. Tool the bead in a single pass with a wet fingertip, wiping the excess onto a paper towel after each stroke. Pull painter's tape right away while the silicone is still wet.
  8. Leave the water in the tub and keep the shower dry for 24 hours (some fast-cure tubes release at 3 to 12 hours), then drain it.

Or hire it out

A handyman or tile pro charges $150–350 to strip and recaulk a standard tub surround, and $250–500 for a large walk-in shower with several joints. Materials are under $20, which makes this one of the widest DIY-versus-hire spreads in the house.

Done. Now the part everyone skips: doing it again on schedule. Log it in OnOtto and the next reminder for bathtub recaulking sets itself.

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Frequently asked questions

Can I just caulk over the old caulk?

No. Silicone will not bond to cured silicone, so a fresh bead laid on top grips only at its edges and peels away in sheets within a few months. It also seals the mildew underneath, where it keeps feeding on soap film and shows through as gray shadows. Removal eats about 20 of the 45 minutes, and it is the step that decides whether the job lasts 5 years or 5 weeks.

Silicone or acrylic latex caulk for a tub?

Use 100% silicone rated for kitchen and bath anywhere water sits: the tub-to-tile line, the shower pan, the drain flange. It stays flexible and ignores standing water. Siliconized acrylic latex tools more easily and takes paint, which makes it right for trim and for exterior work like recaulking windows and doors, but it hardens and splits in a wet joint. For the plain-English difference, see what caulk is.

How long before I can shower again?

Give it 24 hours unless the tube states otherwise; some fast-cure silicones are shower-ready in 3 to 12 hours. Silicone cures by reacting with humidity rather than drying, so a cold, dry bathroom slows it and a warm one speeds it up. The bead skins over in 15 to 30 minutes and looks finished long before it is, which is exactly how people ruin new caulk on day one.

The black mildew came back in a few months. What went wrong?

Moisture, almost always, not the caulk. A bath fan needs to run 20 minutes after a shower to clear the humidity, and plenty of them are undersized or dumped into the attic instead of outside. Squeegee the walls, hang the mat to dry, and leave the door open. If the mildew returns on a joint that also feels soft or gapped, water is already getting behind it, the same failure that makes failing caulk around windows expensive outdoors.

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