How To Caulk A Large Gap Between The Tub And The Wall

Did you know that the gap between your bathtub and the wall is left there intentionally? This allows for some movement and expansion between the tub and the wall and is sometimes known as an expansion joint. However, if you find that this gap is accumulating unwanted moisture, you may want to fill it with a waterproof material that is also flexible. Caulk would be the most suitable material in this case.

In this article, we share with you how you can caulk a large gap.

Deep and Wide Gaps

If you have a very deep or wide gap that is up to 6”, you can make use of a backer rod to help you do the job. There are different types of backer rods you can find in the market, but for this specific purpose, you will want one made of a nonporous material so that it will not end up absorbing water.

Insert the backer rod into the gap so that it is filled completely. Once you are satisfied that it is in place, you can start applying the caulk. You can do this by squeezing a small bead onto each side of the rod.

Gaps Below 1/2 ” Wide

Is the gap between your tub and your wall between ½” and ¼”? If so, you will want to start by using two beads of caulk side by side. One bead should be applied on the edge of the wall, and the other along the edge of the tub. To join both beads, wet a finger and smooth them together. You will want to be careful when doing this to ensure that you do not push the caulk in too far.

If you find that this method does not work or that the gap is deeper than you have realized, stop immediately and take the caulk out. Instead, you should follow the steps outlined in the previous paragraph.

Gaps Below 1/4” Wide

Before filling these small gaps up with caulk, you will need to ensure that the area is clean and dry. For gaps even smaller than 1/8”, regular caulk will do the job just fine, but if your gap is larger than 1/8“, you may want to consider using sanded caulk. You can start by squeezing a bit of caulk into the space. To smooth it out when you are done, simply wet your finger and go by touch.

Making Use of Tools

Depending on the configuration of your tub, you may need to add a tool known as a tub flange. This is usually the case if your tub does not come with a lip already built in. If you are in the process of installing your tub and discover a gap, you can consider attaching a tub flange in this area. Once the flange is in place, you can install the tub over it. To finish it off, apply some caulk on top of the flange.