How to Caulk a Shower
Updated February 20, 2026
Seal your shower with a clean, watertight caulk bead -- prevents leaks, mold, and water damage behind the walls. Under $15 and one hour of work.
Overview
Shower caulk fails before anything else in a bathroom. Every gap, crack, or peel lets water behind the walls. Mold, rot, and expensive repairs follow. Recaulking a shower is a $15 job that takes about an hour of active work. The key to a professional result: remove every trace of old caulk, clean the surface completely, and use painter's tape for straight lines. Silicone caulk only -- latex blends fail in wet environments.
What You'll Need
Safety First
- Ventilate when using caulk remover or denatured alcohol. Open a window or run the exhaust fan.
- Razor blades and utility knives: always cut away from your body. A caulk removal tool is safer and will not scratch tile or fiberglass.
Step-by-Step Instructions
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Remove All Old Caulk
New caulk will not stick to old caulk. Cut and scrape all old caulk with a caulk removal tool, razor blade, or utility knife. Stubborn silicone? Apply caulk remover (DAP Caulk-Be-Gone), wait 2-3 hours, then scrape. Get into every corner -- that is where failures start. Wipe the joint with denatured alcohol on a rag. You want bare tile, fiberglass, or stone on both sides.
Tip: Run your fingernail along the joint after scraping. Feel bumps or film? Keep going. Incomplete removal is the number one reason new caulk fails. -
Clean and Dry the Surface
Wipe the joint with denatured or rubbing alcohol on a cloth. Removes soap residue, body oils, and film. Mold or mildew? Spray with 1 part bleach to 10 parts water, wait 15 minutes, wipe clean. Let the joint dry completely -- 30 minutes minimum with the exhaust fan running. Caulk will not adhere to a damp surface.
Tip: Press on the wall behind the old caulk line. Soft or spongy? Wall material is water-damaged and needs repair before recaulking. -
Apply Painter's Tape for Clean Lines
Run painter's tape along both sides of every joint -- one strip on the shower wall, one on the pan or tub edge. Leave about 1/4 inch gap on each side. Press tape down firmly. At corners, cut tape at 45 degrees where vertical and horizontal runs meet. Work in 3-4 foot sections: tape, caulk, smooth, pull tape, move to the next section.
Tip: Critical: remove tape while the caulk is still wet. Let it skin over and the tape pulls the caulk up with it, ruining the bead. -
Apply the Caulk Bead
Cut the tube tip at 45 degrees -- opening should match joint width (usually 1/4 inch). Pierce the inner seal. Hold the gun at 45 degrees and apply steady pressure while moving at a consistent speed. Fill the joint completely, no gaps. One continuous motion per section.
Tip: 100% silicone caulk only. Look for 'kitchen and bath' or 'tub and tile' on the label -- contains mildewcide. White or clear are standard. Clear hides imperfections better for beginners. -
Smooth and Remove Tape
Immediately after each section, smooth with a wet finger or caulk finishing tool. Dip finger in water with a drop of dish soap -- prevents sticking. One continuous motion, pressing caulk into the joint. Wipe finger between passes. Pull painter's tape slowly at 45 degrees while caulk is still wet.
Tip: Caulk finishing tools ($5-8) produce a consistent concave bead without the mess. Works especially well in corners where fingers are clumsy. -
Cure for 24 Hours
Silicone skins over in 30-60 minutes but needs 24 hours to fully cure. Do not use the shower or get the caulk wet during cure time. After 24 hours, inspect for missed spots or gaps. Clean with alcohol, dry, touch up if needed.
Tip: Running the exhaust fan during cure time helps. Silicone cures by reacting with moisture in the air, but excess water on the surface before full cure can compromise the bond.
Pro Tips
- Do the shower door frame and glass-to-tile joints at the same time. These seams fail just as often as the pan joint and cause the same water damage.
- Replace shower caulk every 3-5 years as preventive maintenance. Do not wait for visible damage.
- Never caulk over mold. Kill it first, dry completely, then caulk. Caulking over mold traps moisture and lets it keep growing.
- For shower doors specifically, only caulk the inside of the door frame where it meets the tile. The outside weep holes at the bottom of the door track must stay open to drain water.
- If the gap between the shower pan and wall is larger than 1/2 inch, use backer rod (foam rope) to fill the gap first, then caulk over it. Caulk alone will not bridge large gaps.
When to Call a Pro
Caulking is always DIY. But if you find soft, crumbling, or moldy wall material behind the old caulk, have a contractor assess the damage before recaulking. If the shower pan is cracked or pulling away from the wall, the pan may need repair or replacement first.