How to Replace and Seal Bathroom Caulk Around a Bathtub

Water is the silent enemy of your bathroom, and nowhere is that more apparent than the seam between your tub and the wall. When caulk begins to pull away, yellow, or harbor black spots, it is no longer just an aesthetic nuisance—it is a pathway for moisture to seep into your wall framing and subfloor. This project is the ultimate low-cost, high-impact defense against water damage. Done well, a new bead of caulk looks factory-applied and stays watertight for years. The secret isn't just in the application; it is in the preparation. If you apply new sealant over old residue or damp surfaces, it will fail within months. Approach this as a surgical task, focusing on removing every trace of the old material and ensuring the joint is bone-dry before the new silicone ever touches the surface.

  1. Strip the Old Seal. Use a plastic caulk removal tool to slice away the bulk of the old sealant. Avoid using metal blades, which can easily gouge your tub or tile finish.
  2. Scour and Degrease. Scrub the joint with a stiff nylon brush and a spray of household cleaner to remove soap scum. Once the loose debris is gone, wipe the entire area thoroughly with a rag dampened with 70% isopropyl alcohol.
  3. Eliminate Hidden Moisture. Use a hair dryer on a low, cool setting to blow air into the gap for several minutes. Ensure the seam is completely moisture-free before moving forward.
  4. Frame Your Clean Edge. Run a strip of blue painter's tape along the wall and the edge of the tub, leaving about an eighth of an inch of space for the caulk line. This ensures a sharp, professional-looking edge that doesn't bleed onto the wall.
  5. Gun It Steady and Smooth. Load your silicone into a caulk gun and cut the nozzle at a 45-degree angle to match the width of your gap. Hold the gun at a steady 45-degree angle and apply consistent pressure while pulling the gun along the joint.
  6. One Stroke to Perfect. Dip your finger in a small cup of soapy water and run it along the bead once to flatten and shape it. Remove the tape immediately after smoothing while the silicone is still tacky.