How to Seal Wall Joints Around a Tub or Shower
You're much better off maintaining the caulk joints around a tub or shower base than cleaning up the mess that results when water penetrates that protective barrier.
In areas where the caulk is still bonded, use a plastic putty knife or (with porcelain tubs only) a single-edge razor to break the bonds between the caulk and the fixture and between the caulk and wall. Hold the putty knife at an angle, with the pointed corner at the edge of the caulk; hold the razor blade at a low angle, with its edge on the tub or wall surface, and push it into the caulk.
Use a flathead screwdriver to scrape out loose caulk. Push the tip into the joint and pull the blade through the caulk. To give yourself greater control, hold the blade in your left hand if you are right-handed (the reverse if you are left-handed), and keep that hand in contact with the tub or shower base as you pull the tool along the joint. For very dry, stubborn caulk, use a chemical for caulk softening and removal, such as 3M Caulk Remover, as directed by the manufacturer.
Repeat steps 1 and 2 as needed until the joint is open and there is no caulk on either the fixture or the wall surface. You may find an excess of caulk on the wall near the fixture, well outside the joint, left over from previous attempts to repair caulk or from too-heavy application of caulk. Remove all of this.
Use a hair dryer or heat gun at a low setting to dry out the joint.
Use a vacuum with a pointed attachment, an old toothbrush or another small brush to remove any loose bits of caulk from the joint. Apply painter's masking tape to the wall surface and the tub or shower pan immediately adjacent to the joint.
Hold the tip of your caulk tube or cartridge against a cutting board and cut off the tip at a 45-degree angle with a utility knife, removing about 1/4 inch (6 mm) to create a 1/8-inch (3-mm) hole.
Holding the caulk tube at an angle, squeeze caulk into the joint until you've slightly overfilled it, then run the tube along the joint. Adjust the pressure, the speed or both to get the desired result.
Smooth the joint. Use a plastic caulk-smoothing tool designed specifically for this task, or use the wetted tip of your finger. Ideally you should do this in a single pass, but you'll likely have to pause because your fingertip is leaving an excess of caulk outside the joint, or because you need to add caulk in some places.
Remove the masking tape immediately after smoothing the caulk, and smooth the joint again with a wet, soapy finger. Wait overnight before using the tub or shower, or at least as long as indicated on the caulk label.
Things You Will Need
- Caulk-removing And Softening Chemical
- Painter's Masking Tape
- Hair Dryer Or Heat Gun
- Cutting Board
- Utility Knife
- Caulk-smoothing Tool
- Flathead Screwdriver
- Plastic Putty Knife Or Single-edge Razor
- Tub-and-tile Caulk
- Vacuum with pointed attachment, toothbrush or small brush
- Don't use grout to fill the joint between the tub and the wall. The different rates of expansion of these dissimilar materials, as well as movement caused by the weight of water in a tub, require a permanently flexible joint filler.
- Avoid patch jobs. Failure in one location indicates the likelihood of future problems. While it may be possible to caulk over failed sections, the bond between new and old caulk usually fails, and the results are unattractive.
- Use only caulk designated for tub and tile use, which is formulated for mildew resistance.
- Metal tools can easily scratch or chip the surfaces of tubs and shower bases.