How to Recaulk a Bathtub
Updated February 20, 2026
Strip old caulk and lay a clean, watertight bead around your tub or shower -- the $15 maintenance job that prevents thousands in water damage and mold.
Overview
The caulk around your tub is the only thing keeping water from getting behind the walls. When it cracks, peels, or develops gaps, water seeps in during every shower. That means mold, rotting drywall, deteriorating framing, and eventually thousands in repairs. Recaulking takes about an hour of active work (plus 24 hours of cure time), costs under $15, and is one of the most important maintenance tasks in any bathroom. The secret to a professional-looking result: thorough removal of the old caulk, a clean dry surface, and the painter's tape technique that gives you perfectly straight lines even on your first try.
What You'll Need
Safety First
- Ventilate the bathroom when using caulk remover or denatured alcohol. Open a window or run the exhaust fan -- some removers have harsh chemicals that irritate eyes and lungs in enclosed spaces.
- Razor blades and utility knives: always cut away from your body. A dedicated caulk removal tool ($3-5) is safer and will not scratch the tub or tile like a razor blade can.
Step-by-Step Instructions
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Remove All Old Caulk Completely
Most important step in the whole process. New caulk will not stick to old caulk -- period. Use a caulk removal tool, razor blade, or utility knife to cut and scrape all old caulk from the joint. Stubborn silicone? Apply caulk remover (DAP Caulk-Be-Gone) and let it sit 2-3 hours to soften before scraping. Pull in strips where you can. Get into the corners -- that is where most failures start. After the bulk is out, wipe the joint with denatured alcohol on a rag. You want bare porcelain or acrylic on the tub side and bare tile or wall surface on the wall side.
Tip: The number one reason new caulk fails is incomplete removal of the old stuff. New caulk will not bond to old caulk and it will peel within weeks. If you can run your fingernail along the joint and feel bumps or film, keep going. -
Clean and Dry the Joint Thoroughly
Clean the joint with denatured alcohol or rubbing alcohol on a cloth. This removes soap residue, body oils, and any remaining film. Mold or mildew (black or pink staining)? Spray with mold remover or 1 part bleach to 10 parts water, let it sit 15 minutes, wipe clean. Then let the joint dry completely -- 30 minutes minimum with the exhaust fan running, or hit it with a hair dryer on cool. Caulk will not adhere to a damp surface.
Tip: Significant mold behind the old caulk line? That may mean the wall surface is compromised. Press on the drywall or backer board behind the joint -- if it is soft, spongy, or crumbling, the wall material needs repair before you recaulk. -
Apply Painter's Tape for Clean Lines
Optional but highly recommended, especially if this is your first time. Run painter's tape along both sides of the joint -- one strip on the tub, one on the wall, leaving about a 1/4 inch gap on each side. Press the tape down firmly so caulk does not seep under. The tape gives you perfectly straight, uniform lines and makes cleanup easy. At corners, cut the tape at a 45-degree angle where vertical and horizontal runs meet.
Tip: Critical: remove the tape while the caulk is still wet (within 5-10 minutes). Let it skin over first and the tape pulls the caulk up with it, ruining the bead. Work in 3-4 foot sections: tape, caulk, smooth, pull tape, move on. -
Apply the Caulk with a Steady Bead
Load the tube into the caulk gun. Cut the tip at a 45-degree angle -- opening size should match the joint width (usually about 1/4 inch). Pierce the inner seal with the gun's puncture tool or a long nail. Hold the gun at 45 degrees to the joint and apply steady trigger pressure while moving at a consistent speed. Fill the joint completely without gaps or excess. Work in 3-4 foot sections so you can smooth the caulk before it skins over.
Tip: Use 100% silicone caulk, not silicone-latex blend. Silicone is waterproof, flexible, and mold-resistant. Look for 'kitchen and bath' or 'tub and tile' on the label -- those contain mildewcide. White or clear are the standard colors. -
Smooth the Bead and Remove Tape
Right after applying a section, smooth the bead with a wet finger, caulk smoothing tool, or wet popsicle stick. Dip your finger in a cup of water with a drop of dish soap -- the soapy water keeps the caulk from sticking to your finger. One continuous motion, pressing the caulk into the joint. Wipe excess from your finger between passes. Immediately pull the painter's tape at a 45-degree angle while the caulk is still wet. Clean smudges with a damp rag.
Tip: Pull the tape slowly and at a consistent angle. Fast or jerky removal lifts the caulk edge and makes it look ragged. If a section does not look right, re-smooth with a wet finger within the first few minutes before it skins over. -
Allow Full Cure Time Before Use
Silicone skins over in 30-60 minutes but needs a full 24 hours to cure. Do not use the tub or get the caulk wet during that time. After 24 hours it is fully waterproof. Inspect the line for missed spots or gaps -- clean with alcohol, let dry, and apply a touch-up bead if needed.
Tip: Pro move: fill the tub with water before you start caulking (after removing old caulk and cleaning). The weight pulls the tub down slightly, opening the joint to its widest point. Caulk while the tub is full. After curing, drain the tub -- it rises slightly and compresses the caulk for a tighter seal. Prevents cracking when the tub is loaded during use.
Pro Tips
- Fill the tub with water first. Professionals always do this. A full tub (300-400 pounds of water) deflects the tub downward, and caulking at that point means the caulk is never stretched beyond its applied state during normal use. This is the single best tip for long-lasting caulk.
- Replace tub caulk every 3-5 years as preventive maintenance, or sooner if you see cracking, peeling, or discoloration. Do not wait for visible water damage -- by the time you see it, moisture has been getting in for months.
- Beginner-proof option: a caulk finishing tool ($5-8) instead of your finger. Various profile shapes produce a consistent concave bead without the mess. Works especially well in corners.
- Clear silicone is most forgiving for beginners -- imperfections are less visible. White shows every flaw but looks cleaner when done well. Match the caulk color to the tub or tile.
- Never caulk over mold. Kill it with bleach solution and let it dry completely first. Caulking over mold traps moisture and lets it keep growing behind the new bead.
When to Call a Pro
Recaulking is always DIY. But if you find soft or crumbling wall material behind the old caulk (water damage), have a contractor assess the extent before you recaulk. If the tub is pulling away from the wall (gap larger than 1/2 inch), it may need to be re-secured first. Standing water between the tub and the floor? That is likely a drain or overflow leak that caulking will not fix.