Most everyone understands the need to caulk the long seams between the wall and the edges of a bathtub or shower pan, or along the rails of a shower door. But often overlooked are the smaller seams around escutcheon plates and the various rings or caps concealing the holes where plumbing pipes or faucet valves come through the wall. If these joints aren't caulked, water can easily get behind them and into the wall. And water in the wall can mean mold growth, rot, and even leaking into the ceiling or floor cavity below the shower or tub.
The best caulk to use in a shower is 100-percent silicone caulk designed for plumbing applications, often sold as tub-and-tile or kitchen-and-bath caulk. Silicone caulk has good adhesive properties and will not only seal cracks but also hold trim pieces to the wall. Although this caulk is sold in full-size tubes for use with a caulk gun, for caulking trim, you may find that a smaller squeeze tube makes it easier to apply the caulk. It's not a bad idea to get a caulk that includes a mildewcide to help prevent discoloration from mold, which is almost always present in bathrooms.
Equipment / Tools
- Clean rags
- Putty knife
- Utility knife
- Bathroom cleaner
- 100-percent silicone caulk
Clean the Surfaces
Thoroughly clean the area you will caulk, using your preferred bathroom cleaner. Rinse the area and dry it with a clean rag. Caulk adheres best to a clean surface, so make sure the walls and trim are completely clean and dry. If you are replacing old caulking, remove all of the old caulk and clean the surface thoroughly.
Prepare the Caulk Tube
The secret to a neat application is cutting the right size opening on the applicator tip of the caulk tube. The lower down on the tube you cut, the larger the opening and caulk bead.
For trim, a 1/4- to 3/8-inch bead is good (you can wipe down the bead to whatever size you like). To cut the applicator tip, remove the cap (as applicable) and use a sharp utility knife to cut off the tip at a 45-degree angle. Some caulk tubes have markings on the tip indicating where to cut for various bead sizes.
The caulk will be easier to apply if it is slightly warm. You can warm the tube by holding it between your hands for a few minutes, or by soaking it in warm water before you cut the tip of the tube.
Place the applicator tip against the shower surface at a 45-degree angle. Apply a small, uniform bead of caulk all the way around each part of the shower trim. It is important to cover the whole seam because water can leak through even the smallest gap.
Shower and tub trim parts you should caulk include:
- Tub spout
- Faucet handle escutcheons
- Shower valve escutcheons
- Bathtub drain overflow plate
Caulking around the showerhead trim is optional, as this area usually isn't prone to much water intrusion. You can judge for yourself.
Smooth the Caulk Bead
Immediately after applying, use a wet finger (some people like to use a damp rag or a sponge) to smooth out each bead of caulk. The goal is to leave a small, neat bead that still fully covers the gaps around the trim. It is important to do this immediately; silicone caulk takes a long time to fully dry but can become less spreadable pretty quickly.
How much caulk is wiped away is up to personal preference. Some people like to leave fairly large caulk lines, but small, thin beads usually look better. A thin line of caulk is just as effective as a large one as long as there are no gaps. Keep in mind that a thicker caulk joint draws the eye, while a thin line will be less conspicuous.
Let the caulk cure as directed by the manufacturer. Silicone caulk usually must dry for 24 hours before it's ready for heavy water contact.
The best way to smooth the caulk bead is with a warm, wet finger: Don't use cold water on your hand before smoothing.