How do you caulk a bathtub or shower?
Short answer: Pick a kitchen-and-bath sealant, such as 100% silicone or a siliconized formula. Remove all old caulk, clean the joint, and let it dry completely. Tape both edges, run one steady bead, smooth it with a damp finger, and pull the tape. Wait the label's water-ready time before showering: 30 minutes for one GE silicone, 4 hours for one DAP sealant.
What caulk should I use around a bathtub?
Use a sealant labeled for kitchen and bath use. Two common types fit wet areas:
| Type | Example from the maker | Water-ready time on label | Mold or mildew claim |
|---|---|---|---|
| 100% silicone | GE Advanced Silicone 2 Kitchen & Bath | 30 minutes | “10 year mold free product protection” |
| Siliconized sealant | DAP Kwik Seal Ultra Kitchen & Bath | 4 hours | Mildew resistant, “lifetime mould and mildew guarantee” (DAP Canada) |
DAP’s bathtub guide recommends its siliconized Kwik Seal Ultra. GE’s product listing describes its sealant as “100 percent silicone” and “100 percent waterproof.” Formulas change, so read the tube you buy. Its label is the final word on use and cure time.
How do I remove old caulk?
DAP’s method removes the old caulk completely before applying new sealant:
- Soften the old caulk with a commercial caulk remover.
- Slice through it with a utility knife.
- Scrape off what remains with a razor blade or a strong cleaner. Take care not to scratch the tub.
- Clean the surface again.
How clean and dry does the joint need to be?
DAP says to clean the surface and let it dry completely before caulking. As a rule of thumb, soap film or moisture left in the gap can weaken adhesion. If the bathroom stays humid, run the exhaust fan while the joint dries.
If you find mold behind the old caulk, deal with it before sealing it in. See how to get rid of bathroom ceiling mold for cleaning and moisture control that also applies to tub surrounds.
How do I apply a clean caulk line?
- Tape the edges. DAP suggests painter’s tape to mark where caulk should and should not go. Leave a narrow, even gap along the joint.
- Wear gloves and ventilate. DAP recommends both.
- Cut the nozzle small. A smaller opening gives more control. You can always cut it larger.
- Hold the gun at 45 degrees. DAP says to start in one corner and work toward the center. Then start from the opposite corner and meet in the middle.
- Keep steady pressure. Move at an even pace so the bead stays a uniform size.
How do I smooth (tool) the bead?
DAP says to smooth the bead into a concave curve with a damp cloth and your finger. Tooling also presses the caulk into the joint. A plastic caulk-finishing tool can be used instead of a finger.
Pull the tape right after tooling, while the caulk is still wet. Then clean up the edges.
How long before I can shower?
Follow the cure time on your tube. The two examples above differ a lot:
| Product (per maker) | Tack-free | Water ready |
|---|---|---|
| DAP Kwik Seal Ultra | About 15 minutes | 4 hours |
| GE Advanced Silicone 2 | Not stated on page | 30 minutes |
“Water ready” is not the same as a full cure. If your schedule allows, waiting longer before heavy use is a reasonable cushion.
Safety notes
- Ventilate the room while removing old caulk and applying new caulk. Check the remover’s label for its own ventilation directions.
- Razor blades slip easily on smooth tubs. Keep the blade low and cut away from your hand.
- Wear gloves, as DAP recommends.
Quick answers
Can I caulk over old caulk? Not recommended. DAP’s method removes the old caulk fully, then cleans and dries the joint first.
Should I fill the tub with water before caulking? Some installers suggest it so the tub settles under weight before sealing. The maker pages we reviewed do not mention it, so treat it as an optional tip.
Is silicone or siliconized caulk better for a shower? Both are sold for kitchen and bath use. The GE silicone listed here is water ready in 30 minutes. The DAP siliconized sealant takes 4 hours.
How long does bathtub caulk take to dry? It depends on the product. DAP Kwik Seal Ultra is tack-free in about 15 minutes and water ready in 4 hours.
Why does my new caulk keep peeling? Common causes are leftover old caulk, soap film, or moisture in the joint. Remove it, clean, dry fully, and re-caulk.