Re-Caulk a Bathtub Seam
Category: Plumbing ·
Difficulty: Beginner ·
Time: 2h ·
Estimated cost: $22
Tools needed
- Caulk gun
- Caulk removal tool
- Plastic finishing tool
- Utility knife
- Microfiber rags
Materials needed
- 100% silicone bathroom caulk (white) (1 tube)
- Painters tape (1") (1 roll)
- Isopropyl alcohol (1 qt)
- Bleach cleaner (1 qt)
Execution steps
Remove old caulk
Score both edges with a utility knife. Pull the bead off in strips with the removal tool. Get every scrap — silicone won't stick to old silicone.
Duration: 30 min
Kill mold and clean
Spray bleach cleaner on the joint. Scrub with a brush. Rinse. Wipe with alcohol and let dry 30 minutes.
Duration: 45 min
Tape both sides
Lay painters tape on both surfaces 3/16" off the joint. This is the secret to a razor-straight bead.
Duration: 15 min
Run the bead
Cut the tube tip at 45 degrees, 3/16" opening. Apply steady pressure, move at a constant speed along the joint.
Duration: 15 min
Tool and tape pull
Drag the finishing tool firmly to shape the bead. Immediately pull both tape strips away at 45 degrees BEFORE the caulk skins.
Duration: 10 min
Cure 24 hours
Don't fill the tub or shower for 24 hours. Run the fan; it cures faster in dry air.
Duration: 5 min
Safety first
- Use 100% silicone, never "tub & tile" latex caulk — latex grows mold within months.
- Ventilate while applying — uncured silicone fumes irritate lungs.
When to hire a pro
If you find rotted drywall or black mold behind the old caulk, stop — call a mold remediator before you re-caulk over a moisture problem.
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