How to Caulk a Shower or Tub

An unsung hero of bath construction, the caulk in your tub or shower provides an important barrier against water damage in your home. If allowed to seep behind waterproof finish materials like acrylic, tile, or enameled steel, water can reach the wood framing and subfloor materials in your bathroom, leading to rot, mold growth, and even damage to finish materials in adjacent rooms.

Keeping a reliable seal on the seams of your bathtub or shower enclosure with appropriate caulk is a simple but essential maintenance task.

Planning to caulk your shower

Caulking a shower is a manageable project for most homeowners, but the job could put your shower out of service for more than a day. Be sure to plan ahead to allow adequate time for preparation, application, and drying or curing.

Also, choose your caulking products carefully. Select caulk designed for use in wet environments that will inhibit the growth of mold and mildew. These products can be found in stores and home centers, are typically labeled for use in the kitchen and bath, and are generally available off the shelf in just a few colors: clear, white, and almond.

Finally, consider whether you’d prefer to work with silicone or latex caulk. Silicone is preferred by pros, as it lasts longer and remains more flexible and effective over its lifetime than latex. However, latex is easier to handle and clean up—a good option for caulking amateurs. In either case, a standard tube of caulk provides more than enough product to seal a typical shower. Practice your application technique on a sheet of cardboard or other scrap material before getting to work.

Tips for caulking a shower

While caulking a shower is a relatively simple project, keeping a few factors in mind can help you pull the job off flawlessly.

1. Use quality tools and materials—Even if caulking a shower is a job you only do once every few years, it pays to invest in quality. A higher-grade caulking gun will make the job much easier than economy models and the best caulk for the application will help the job last.
2. Practice—Even the pros start somewhere. Take some time to practice applying caulk on scrap material before taking the plunge. It’s worth the time spent getting familiar with the products and tools to avoid having to start over.
3. Know where to caulk—Only apply caulk where it belongs—generally along the vertical and horizontal planes where finish materials meet. Remember that some areas in a shower are designed for drainage and should not be sealed with caulk, such as the weep holes in a shower door track or the drain overflow beneath a tub faucet. If you are experiencing a leak or question whether a surface should be sealed, check with a pro.

Tools and materials for caulking a shower

• Utility knife
• Caulk removal tool
• Caulk removal solvent
• Masking tape
• Caulking gun
• Caulking tool
• Rags or paper towels
• Kitchen and bath caulk

Prepping your shower

Though not the most glamorous step of most home improvement projects, preparation is often the most important step. Caulking a shower is no exception. In order for new caulk to adhere properly and provide protection from water infiltration, the application site must be completely clean and dry. That means all existing caulk, along with any residue, mold, or other gunk must be cleaned from the tub or shower surface. This can be a tedious process and will likely take much longer than the application of new caulk.

1. Remove old caulk—Use a utility knife or caulk-removal tool to cut through existing caulk. Peel or scrape away as much material as possible.
2. Remove residue—Use an appropriate product to remove any caulk residue. For silicone caulk, a solvent-based caulk remover will be necessary and are available at home centers.
3. Clean surface—Use an appropriate cleaner to remove surface contaminants. If mold or mildew is present, use an effective fungicide or mildewcide to eliminate its spread.
4. Dry completely—Allow all surfaces to dry thoroughly to allow for proper adhesion and prevent trapping moisture behind the new caulk. Run a fan in the area or use a hair dryer to speed up the process if necessary.

How to caulk your shower

Applying caulk is a simple process but getting a crisp, clean line takes a bit of finesse. Even the pros swear by different methods, so take the time to get familiar with the tools and products involved to determine what works for you.

1. Mask the area—Masking is an optional step, but it can be a lifesaver for beginners. Apply masking tape to each side of every joint. Masking prevents getting excess material (which is tough to clean up) on the surface of your tub or shower.
2. Prepare caulk—Use a utility knife to cut the tip from the tube of caulk. Cut off only a small bit to allow for a fine bead of caulk, which will be easier to control and smooth, or “tool.”  
3. Load caulking gun—If using a standard tube of caulk, pierce the seal of the tube by poking it with a wire, fine nail, or the seal punch on your caulking gun, if equipped. Load the tube into the gun and adjust the plunger.
4. Apply caulk—Hold the tube or caulking gun at a slight angle. With steady pressure, squeeze an even, fine stream or “bead” of caulk on each seam of the shower to fill the gap between materials.
5. Tool caulk—With a caulking tool or simply a wet finger, smooth the bead of caulk to remove excess material and create a clean finish.
6. Remove masking—Carefully pull away masking tape before the caulk begins to dry.
7. Allow to set—Leave the new caulk undisturbed for the minimum time recommended by the manufacturer. Do not use the tub or shower or attempt cleanup that might interfere with the caulk.
8. Clean Up—Use a plastic scraper, caulk-removal tools, or solvent to remove excess caulk from the shower surface. Be careful not to compromise the newly applied caulk.