Whether your shower is a free-standing shower unit or part of a bathtub surround stall consisting of an acrylic shell or ceramic tile, it is critical to seal the joints around the base and corners of the shower with a good-quality silicone caulk. Left uncaulked, the joints can allow water to seep behind the surface, where it can rot the wall structure or foster the growth of mold. Of all locations in a bathroom, the walls of a shower stall are the most susceptible to moisture infiltration, so it is critical that you regularly inspect the joints and make sure the caulk is doing its job—blocking water from seeping through the wall.
Caulking a shower stall requires the same basic techniques as used for any other bathroom location, though it is even more important here than for other areas. A great caulk job can last up to five years, but check the shower walls yearly to catch problems before they can become serious. Signs of caulk going bad include: caulk pulling away from base of the shower, mold growth, flaky appearance, chunks of caulk missing from joints, and moisture buildup along the joints. With tiled showers, loosening tiles can be a sign that water is infiltrating behind the wall. If you spy any of these symptoms, it’s time to re-caulk.
Choosing the right caulk for your project is a vital first step. There are two types of caulk that home improvement stores offer—latex and silicon-based. It is highly recommended that you use a 100% silicone-based caulk for any application where water and moisture are prevalent, such as toilets, showers, and sinks. (For other projects, such as sealing drafts around windows and doors, latex caulk is a good choice.)
Equipment / Tools
- Razor scraper or caulk removal tool
- Caulk-smoothing tool (optional)
- Utility knife
- Liquid caulk remover (optional)
- Household cleaner
- Sponge or cloth
- 100% silicone caulk (squeeze tube or caulk gun tube)
- Paper towels
Remove the Old Caulk
Remove all old caulk with a razor scraper or caulk removal tool. You will need to scrape all surfaces the caulk will touch, including the tile, tub surface, or wall panels surrounding the joint. Don't forget the joints around escutcheon plates on shower valves and the arm for the showerhead. With acrylic shower stalls, work carefully to avoid scratching the surfaces. You may have to repeat this step, because new caulk will not adhere unless the surfaces are completely smooth and clean. You can also apply a liquid caulk remover to help this process.
Once all caulk is removed, use a cloth or sponge and a household cleaner to clean the surfaces. Thoroughly rinse away the cleaner using a damp rag, then let the surfaces dry completely before applying the new caulk.
Some pros like to cover the surfaces on either side of the joint with painter's tape. After the caulk is applied, the tape can be pulled away, creating sharp edges to the caulk bead.
Silicone tub-and-tile caulk is available either in tubes that fit into a caulk gun or in squeeze tubes. Either way, begin by cutting the tip of the tube at a 45-degree angle. Most tubes have an indicator line on the tip to show you where to cut. If the gaps you need to fill are wide, cut close to the base of the tip, which will create a thicker bead of caulk. With narrow gaps, cut closer to the end of the caulk tube tip.
Apply an even, continuous bead of caulk along the joint, drawing the tip of the tube slowly along the gap while applying even pressure to the tube. Make sure the gap is full of caulk, but don't worry if the caulk bead is not yet fully smooth.
Make sure to also cover the gaps around the escutcheon plates for the shower valve and showerhead.
Smooth the Caulk
After the gap is full of caulk, use your finger or a caulk-smoothing tool to smooth out the bead of caulk and force it into the joint. Draw your finger or the tool along the length of the joint, removing excess caulk with a damp rag as it builds up on your finger. Avoid overworking the joint; the goal is an angled or slightly concave bead of caulk that will repel water. If the caulk bead is too concave, it will collect water and foster the grown of mildew
If you notice any gaps in the caulk bead, carefully apply additional caulk and smooth it with your finger.
Clean the Surfaces
Even the most careful application can leave a small amount of caulk on adjoining surfaces, so use a damp sponge or cloth to clean up any caulk residue. But be very careful not to touch the caulk bead with your wet sponge, which can ruin the job.
Let the Caulk Dry
Let the caulk completely dry, according to manufacturer's directions. With most caulk products, this means not using the shower for at least 24 hours until the caulk thoroughly dries and cures.