How to Caulk a Bathtub
Part of our Bathtubs guides.
Fresh caulk stops water getting behind tile and makes the bathroom look newer.
| Time | 1-2 hours + cure |
|---|---|
| Difficulty | Easy |
| Tools | Caulk remover tool, rubbing alcohol, painter's tape, 100% silicone, caulk gun |
Step by step
- Remove old caulk. Cut and scrape it all out.
- Clean. Wipe with rubbing alcohol; let dry completely.
- Fill the tub. Filling a tub with water widens the joint so caulk doesn't crack later.
- Tape. Tape both sides of the joint for straight lines.
- Apply. Run a steady bead.
- Tool. Smooth with a wet finger or tool; remove tape immediately.
- Cure. Wait the full cure time (often 24 hours).
Tips & common mistakes
- Use mold-resistant 100% silicone in wet areas.
Choosing the right caulk
Use 100% silicone or a silicone-based kitchen and bath caulk labeled mold-resistant. Acrylic latex caulk is easier to tool and paintable, but less durable in wet areas. Avoid caulking over old caulk; it won't bond and will peel.
Removing old caulk completely
Use a plastic caulk removal tool or utility knife, then a caulk remover gel for residue. Wipe with rubbing alcohol. Any trace of old silicone or soap prevents adhesion.
Why fill the tub first
A filled tub sinks slightly under the weight of the water, widening the joint. Caulking in this position means the joint compresses when empty instead of stretching and tearing when you fill the tub for a bath.
Getting a clean line
Cut the nozzle small at a 45° angle; you can always cut more. Push the bead ahead of the nozzle rather than dragging it. Tool once with a wet finger or tool and pull the tape immediately while the caulk is wet.
Cure time
Many silicones are touch-dry in about 30 minutes but need around 24 hours before getting wet. Check the tube.
Frequently asked questions
How often should I re-caulk?
When it cracks, peels or stains; often every few years.
Silicone or acrylic caulk?
Silicone is more durable and waterproof in wet areas; acrylic is easier to tool and paint.
Can I caulk over old caulk?
No; new caulk won't bond reliably. Remove the old caulk completely.
How wide should the bead be?
Just enough to fill the gap, usually about 1/8 to 1/4 inch.
Why does my caulk keep cracking?
Movement in the joint, applying caulk with the tub empty, or poor surface prep.