Your Step-by-Step Guide to How to Caulk a Shower

Let's start with the important basics: You need to choose the right kind of caulk for your shower. Not all varieties hold up against the heat and moisture of a bathroom, especially when you want it to last for more than a few years. 

You'll find seemingly endless varieties of caulk at the hardware store, but your main options are latex and silicone. Pure silicone caulk is often your best option for sealing a shower. Silicone is flexible, expands with the changing temperature of your bathroom, and is resistant to mildew and rot. You can expect silicone caulk to last up to 20 years when it’s properly applied. But keep in mind that it can be tricky to handle due to its thick, sticky quality and it cannot be painted. 

A combo of latex and silicone is a bit easier for home use. Caulk that’s only made of latex cannot handle moisture, but since it's paintable and spreads more smoothly, some manufacturers combine it with silicone. However, this mixture will not last as long as pure silicone against mildew and cracking.

One of the top reasons caulking cracks and loses its seal is poor application. If the person who last applied the caulk rushed the job, you might find several layers of old caulk on top of one another.

When you’re ready, use a utility knife to carefully remove the old caulk and avoid scratching the tile beneath it. You can also purchase a solvent, such as an organic solvent called mineral spirits, from the hardware store to soften the caulk. But much like the knife, it can damage some tub or tile materials. Double-check the solvent container to make sure it's compatible with your fixtures.

Now is also a good time to take care of any cracked tiles or grout around the areas you're caulking. Fixing cracked grout is a very manageable DIY project, but you can also call in a professional for regrouting services if you need to retile the whole shower. Basically, you don't want to remove your freshly applied caulk for other repairs anytime soon, so you should complete all of your outstanding shower projects now.

Once you've removed the old caulk, examine the surrounding area, as well as underneath the old line, for mold. You can often remove shower mold and mildew with basic household items like vinegar and baking soda or hydrogen peroxide, but be sure to wear gloves, goggles, and a mask while cleaning. 

Once the mold is gone, wipe down the area with dish soap and warm water. Let the area fully dry before you break out the tape and caulk. The new caulk will not properly seal to wet tile. If you're in a hurry to get back to your weekend, use a hairdryer to speed up the process.

Blue painter's tape will be your best friend during this step. Freehanding the caulk line may look like an easy job, but one slip-up can put a snag in the process. Surround the area with two lines of tape, especially when using silicone caulk because it can be sticky to remove.

Line one strip of painter’s tape along the tile above the joint and another below, leaving at least a quarter-inch opening for the seal of the caulk.

A caulk gun is a critical tool when applying caulk properly. Not only will the caulk gun help you squeeze a smooth and steady bead along the joint, but it will also allow you to take breaks as needed. Cut the tip off the top of the new bottle of caulk right above the marked area for narrow lines, which will ensure a smooth but precise flow of caulk without sloppy application.

Once you get the bead started, hold the caulk bottle at a 90-degree angle and move it in a straight, continuous line. Don't worry about small bumps, you'll smooth them out during the next step.

Wet your finger and push it gently against the bead of the caulk in a smooth motion. This action will create a rounded bead that smooths naturally with the shape of the joint. It will also even out any bumps that formed during the initial application. You can also smooth the caulk with a spoon or a wet popsicle stick.

Before the caulk dries, remove the tape one piece at a time, being careful not to bump the caulk line. If you have a large area to caulk or you want to work in sections, tape the next area and start fresh as your first line starts to dry.

Follow the instructions on your bottle of caulk to determine how long to let the caulk cure, but you'll likely need to wait about 24 hours before you can safely apply water again.