How to Caulk a Tub Surround

How to clean out old caulk and apply new, durable caulk around the bathtub.

Step 1: Remove the old caulk and clean the joint

When the caulking around a bathtub starts to crack and become a cozy home for dark stains that signal mold, it’s time to replace it. The caulk is the watertight seal between the bathtub and the wall. Once the caulk’s integrity is compromised, water can invade the wall, causing rot in the framing around the tub. Pick up a 5.5-fl.-oz. tube of tub-and-tile caulk and you can clean and recaulk the tub in less than an hour.

Laying a smooth, clean-looking bead of caulk is tricky. If it doesn’t go right, you can wind up with sticky caulk all over the place and a sloppy-looking job. It takes a little technique and practice to lay a caulk bead like a pro, but this article will set you on the right path.

Before you recaulk your bathtub, you must completely remove the old caulk. Clean the joint so the new caulk will bond properly, creating a watertight seal (Photos 1 – 3).

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Step 2: Re-caulk the joint

Fill the bathtub with water before caulking. The water weight will maximize the width of the tub/wall joint and prevent future stress and cracking. Once your caulk bead is dry, you can drain the water.
    
Laying a uniform bead of caulk requires constant pressure on the caulk tube. The bead should be sized so only a slight amount wipes off when you drag your finger over it. As the caulk tube empties, you’ll find it increasingly difficult to keep constant pressure on the tube and lay a uniform bead. Photo 4 shows the size of the caulk bead and how to repressurize a partially spent caulk tube.

Finish the bead and clean off any excess caulk as shown in Photo 5. If you’re having trouble smoothing the bead of caulk, try rewetting your finger or using a different one. The tile corner joint is just as important as the tub joint. Caulk it as shown in Photo 6. Allow the caulk to dry for 24 hours before using the bathtub.

Trim Tip for a Perfect Joint

Cutting the right size opening at the tip of the caulk tube is critical for a clean, smooth bead. A large opening will spread too much caulk into the joint and you'll wind up getting it all over the place. It's better to cut the tip too small at first because you can always recut it if necessary. Use a utility knife to cut the tip of the caulk tube at a 45-degree angle so the opening is about the diameter of a wire coat hanger.

Caulk tube tip Caulk tube tip cut at 45 degree angle
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