How should I fill the 1/2″ gap between my tub and tile in my DIY bathroom remodel – grout, caulk, or both?
Asked by Therese Fleck 
6 months ago
Last Updated: May 30, 2024
Hey there! So, Iām tackling my first bathroom remodel as a DIY project. I goofed up big time by not making sure the tub was level (lesson learned there), and now I have a 1/2ā gap between the tub and the tile (which is nice and level). Any suggestions on how to fill in this gap? Should I use grout, caulk, or maybe a combination of both? I really appreciate any advice you can give!
Use silicone-based caulk for areas that will be exposed to water
I usually don’t start with a full tile. Instead, I measure the total height and, to avoid a very narrow cut at the top (especially when going up to the ceiling), I recommend cutting the first row in half. This method can help address the challenge of an uneven tub. Finding the right fix for this situation can be tricky. One option is to grout first and then apply a bead of caulk.
Tip: Start by finding your low point and beginning with a full tile there. This is a lesson learned the hard way by anyone who has tiled before. Haha
Once you’re ready, fill with grout and cover the grout with matching silicone, including the vertical corners. The silicone will help secure the grout in place as the tub and walls experience different movement.
The application process for the matching tube is quite messy and sticky. I highly suggest taping the tub lip and corners, leaving the desired gap to be filled. After applying the silicone, lightly spray with a cleaner (like windex), smooth it out, then remove the tape. This method can help you avoid many headaches.
Consider looking into decorative trim tiles to cover the gap and minimize the visual impact of the level difference. While this method may not be traditional for tile attachment, it can be effective. Many people in this group have faced this issue before.
Sometimes, you have to think creatively to find a solution.
Using wood shoe molding is a common practice for similar situations. Tile just requires different materials for attachment.
Would it be worth the hassle to get the tub leveled? It might save you trouble in the long run. If not, you can grout and caulk. Or if you have extra tiles to cut and add in, it might be slightly noticeable. Another option is using 1/4 round trim with caulk all around. It might be slightly noticeable, but you could also have fun and be creative with the trim.
You should both grout it and apply a bead of caulking on top.
Try removing the bottom 2 or 3 rows to even out the tub.
Just silicone it, no problem.
The gap is too large for silicone, and you should avoid the grout touching the tub as it may cause cracking. Your best option is to purchase a matching tile trim such as a pencil trim and install it, even if it means installing it over the current tile.
For the next project, make sure to begin your tile installation at the lowest point and then cut it to fit.
I went with vinyl molding this time.
Try getting the same tile but in a longer length, maybe even a different color. Remove the last row and replace it with the new tiles.
Why keep going after the initial row?
Clearly, they began from the top and progressed downwards
Knew that only tiling one line would be strange. The entire wall needed to be tiled. Duh!
Opted for a fiberglass tub that I already secured with mortar, so there was no going back on the tub.
Swearingen definitely didn’t start at the bottom; no way did he start at the top!
Swearingen here – I began by leveling the tile from the bottom up. If I didn’t do that, I would’ve had to cut all the edge pieces at angles.
Why not just trim the slivers off the bottom and start at the top of the tub? It would have made the whole process much easier.
Swearingen This was my first time trying to remodel a bathroom, and I made a mistake. You live and you learn
It’s too late now, but if you had realized it wasn’t level, you could have adjusted the 2nd row by half a tile height and worked from there. Then, you could have gone back and cut the pieces to fit the first row.
Cut the tile into strips.
Your tub looks a bit off level in the photos. It seems like it’s lower on the drain side. Have you considered lifting the bottom row of tiles to re-level it? How would the gaps look if you did that?
Alright, you live and you learn, right? So you didn’t level the tub, but did you at least bed it in mortar? If not, then unfortunately you’ll have to take it out. Without proper bedding, it will crack and fail. But if you did bed it and want to keep it, just caulk it. I know adding a trim row or decorative tile sounds nice, but the last row is already in place. It seems like you used redgard for waterproofing (great job!). Just be careful because removing tiles could damage that waterproofing. You might be able to patch any damaged areas, but it might not be worth the effort. You can either remove two rows and level the tub or use silicone instead.
I ended up messing up the tub, so it couldn’t be fixed, unfortunately
Hey there! ‘t worry, mishaps are common in DIY projects. To fill the 1/2″ gap between your tub and tile, the best solution is to use backer rod and silicone caulk. Here’s what you need to do: 1. Insert a backer rod into the gap for a strong base. 2. Apply silicone caulk over the backer rod. Silicone is perfect for moisture-prone areas like bathrooms. Remember, grout won’t work for such gaps as it can crack. Caulk is the way to go for a professional finish. Good luck with the rest of your renovation! Robert
Recommends using caulk that is specifically made to match the grout – don’t you think so? The same type of caulk you would use in, for example, the two vertical corners and around the other lower edges?
Bullnose tile
Just throwing some ideas around… How about excluding the bottom row and cutting it into smaller pieces? Try starting fresh to spark a new idea. Perhaps even try really thin slices?
Consider getting a PVC Bead trim in the same color as the tub (which appears white). These trims are typically about 1/2″ thick and 8′ long, coming in various shapes that are easy to cut. They usually cost around $5. Matching the tub color will make the trim blend seamlessly with the tub, rather than the tile, resulting in a flawlessly finished tile job.
How about swapping out the bottom row for a wider coordinating tile that can be trimmed? This will give it a more intentional decorative look.
I had a similar experience with a contractor years ago, and let me tell you, it did not end well. I was left feeling pretty upset and didn’t know how to fix it. Eventually, it even got moldy and I had to remove it. I think the best solution, which I didn’t know about at the time, is to use a pvc trim and seal it with a small bead of caulk. It will look fantastic!
Why did you lay it beyond the first row? You should have seen it
The challenge is that it’s a fiberglass tub that I already secured with mortar, so there was no way to change the tub.
You could consider adjusting the spacing and levels to create an illusion and prevent the large gap on half the tub…
You could also try trimming some tiles so they align evenly after a few rows (full on one side with a gap, slight cuts on the other side).
I’m not sure what else would be helpful at this point, besides using vinyl trim or molding like suggested
If there are still large gaps after cutting additional tiles, you can use mortar or caulk once the spaces are smaller
We encountered a comparable problem with our tile not meeting the tub closely. The gap was too large for caulking. We took out the bottom row of tile, inserted a tile liner, and then reinstalled the bottom row of tile. Initially, I found it awkward, but it turned out to be the only remedy without starting from scratch. Now, I hardly even see it.
Not the best situation and everyone has already pointed out how the tile should’ve been cut for the first row. Since the tub can’t be moved and you don’t want to remove tiles, there are only a few options. 1- Get backer rod and caulk that closely matches your tile color. Mask above and below and caulk. It won’t look amazing, but it’s a simple fix. (Hopefully your tile covers the tub flange?). Also, I’d recommend filling the tub with water before caulking – the weight can sometimes cause the gap to slightly expand. I’d suggest trying this first to see how bad it looks. 2- Try finding tiles from the same collection that are taller. Remove the first row and cut to fit the new tiles for row 1. Alternatively, choose a taller accent tile. You might come across tiny pencil-type tiles that could work, but that usually ends up looking the worst.
Vinyl or PVC molding and attach it to the tub so that the part that meets the tile is level. Having it out of level won’t be as noticeable. Just using caulk to fill it would look pretty bad after six months.
I find it amusing that you asked, “Grout? Caulk?…Grout and Caulk?” Haha, sorry I’m not much help, but I enjoy hearing someone else say the things I would ask aloud.
A thin piece of molding or a thin tile edge would be attractive and practical
On a positive note, it could have been worse by being unlevel on the non-drain side š I hope you find an idea that brings you joy!ā„ļø
You gotta start somewhere, right? How about just caulking it? Fill the tub, tape off the tile and tub, and try to make the caulk line look thinner by running tape tightly along the edges. Next time, use a spacer to run the tile off the tub. If the tub is slightly off, the gap won’t be as noticeable in the tile compared to a 1/2 inch gap. Some people use lasers, but in an old house, it’s more important to go with what looks best to the eye rather than what’s perfectly level.
Try finding a bullnose small round tile edge from somewhere, it could be the solution for this project