How to Remove Old Caulk and Replace Caulk Around a Bathtub

When we moved into the Dogwood House, the hall bathtub had that look - gray, peeling caulk with little black spots of mildew no amount of scrubbing would touch. It made the entire bathroom feel dirty even right after I cleaned it. Replacing old caulk is one of the cheapest, fastest bathroom upgrades you can do, and it protects the wall and subfloor from water damage, too.

It's also one of those jobs that's 80% prep. Take the time to get every bit of old caulk out and the joint bone-dry, and the new bead practically lays itself.

How much caulk do you need?

Most tub surrounds take one tube with plenty to spare, but if you're doing a tub and a shower - or a big garden tub - it's worth running the numbers so you only make one trip to the store.

Step 1: Soften the old caulk

Old latex caulk often peels right out. Silicone is stubborn. Either way, a caulk remover gel makes the job much easier: apply a thick layer over the caulk, wait the time on the label (usually 2-3 hours), and it softens enough to come out in long strips. For silicone, a hair dryer on medium works in a pinch.

Step 2: Cut and scrape out the old caulk

1. Slice both edges. Run a sharp utility knife or caulk removal tool along the top and bottom edge of the bead, holding the blade nearly flat so you don't scratch the tub.
2. Pull the strip. Grab the end with your fingers or needle-nose pliers and pull it out slowly.
3. Scrape the residue. Use a plastic scraper on acrylic or fiberglass tubs; a razor scraper is OK on porcelain and tile if you're careful.
4. Dig out the joint. Make sure nothing is left inside the gap - a thin film of old silicone will keep new caulk from sticking.

Step 3: Clean, kill mold and let it dry

Wipe the whole joint with rubbing alcohol to remove soap scum and silicone residue. If there's mold or mildew in the gap, spray it with a 1:10 bleach-to-water solution, let it sit 15 minutes, rinse and dry. Then the hard part: wait. Run the exhaust fan and let it dry for 24 hours if you can. Caulk over moisture is caulk that fails.

Step 4: Fill the tub and tape the joint

This is the trick most people skip. Fill the tub with water before you caulk. The weight flexes the tub down slightly so the joint is at its widest - the new caulk then compresses instead of cracking when someone steps in.

Next, run painter's tape along both sides of the joint, about 1/8" above and below the gap. It's the easiest way to get a perfectly straight, professional-looking line.

Step 5: Caulk the tub

1. Cut a small tip. Snip the nozzle at a 45° angle with a hole a little smaller than the gap - you can always cut more.
2. Push, don't pull. Hold the gun at 45° and push the bead ahead of the nozzle in one steady motion, corner to corner. Pushing forces caulk into the gap.
3. Tool it. Dip a finger in soapy water (or use a caulk tool) and drag it along the bead in one pass to smooth and press it in.
4. Pull the tape right away. While the caulk is still wet, peel the tape away at an angle, away from the bead.

Step 6: Let it cure

Leave the water in the tub until the caulk has cured, then drain it. Check the label for cure time - typically 24 hours before the shower gets wet, though some fast-dry kitchen-and-bath formulas are ready much sooner.

Common caulking mistakes

• Caulking over old caulk. It won't bond, and the mold underneath keeps growing.
• Too big a bead. A huge bead looks sloppy and takes forever to cure. Smaller is better.
• Overworking it. One smoothing pass. Going back over half-skinned caulk drags and wrinkles it.
• Using the wrong caulk. Painter's caulk cracks and molds in wet areas; use a kitchen and bath product.

Keep the rest of the bathroom looking fresh

Once your caulk is crisp and white, the grout usually starts looking dingy by comparison. We fixed ours with grout paint for under $20 - see how we painted our grout. And if you're ready for a bigger refresh, here are our favorite budget bathroom makeover ideas.