Do You Grout Or Caulk Between Tile And Tub? (Explained)

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It can be a difficult decision to determine whether grouting or caulking the space between a tile and a tub is necessary.

The gap between a bathtub and the tiles must be filled with caulk. This space is generally a quarter-inch, but it could be a little bit wider. Anything between ¼” and 1/8” could be filled with siliconized acrylic sealant. If the gap is broader than 1/8”, fill up the space with sanded caulk.

Modern minimal bathroom with large tile bathtub

Can You Caulk Over Grout in Shower Corners?

Bathrooms should always look clean and hygienic; every part of these must be neat, including elements such as the sink, toilet, shower, and bath. Then, corners must have a tidy finish to give a hygienic appearance to the bathroom, and it also will look beautiful and flawless. Little details matter in interior decoration!

Sealing tiles corners is one of those small details that people should care about it. The tile edges must have a smooth finish, and designers achieve this immaculate look by grouting or caulking.

Though tiles come in diverse designs, and the edges can vary according to the shape, the space between each tile should be sealed.

Then, some people decide to grab the bull by the horns and redesign their rooms by themselves or fix some details. Sealing tiles corners becomes a difficult task in areas like bathrooms and kitchens.

Moreover, people wonder if they should caulk or grout the tiles and if they should caulking over grout in case of cracking.

Caulk is made of flexible polymers, and even when grout may include a minimal portion of polymers, they do not go well together. The siliconized acrylic sealant used for titling will not bond well with the grout. After a few months, you will see how the caulk peel off.

Even when titling grout tends to be smoother than regular grout, the porous surface retains water –– even if you see it super dry –– some water will remain there.

Then, if you applied a silicone-based caulk over the grout to fix a crack, you will see how some mold starts growing between both sealants.

Grout is a mixture of cement, water, and sand that is used to fill gaps, seal joints, and connect concrete sections. This mix of water, sand, and cement is water-resistant once had dried; because of this, designers and builders prefer grout over other joint compounds.

Construction workers can use different cement, water, and sand measures to create a specific texture on the grout, resulting in a type of grout. When we need to fill gaps between tiles or fill the space in the shower corner, we should use titling grout.

This mixture is sand-based or cement-based, and sometimes, it is mixed with polymers. Titling grout is smooth and highly resistant to water, so it can endure the kitchen or bathroom ambient.

Caulk is a material made of flexible sealing compounds such as silicone, latex, or polyurethanes.

People can find caulk in stores, and this does not need any previous preparation. Commercial caulks come in a tube with a convenient applicator; the person only needs to cut the tip and start applying it.

It may be easier to prepare and apply, but commercial caulks have a few variants. We can find acrylic or vinyl latex; acrylic, siliconized, or pure silicone sealant; adhesive, butyl rubber, or asphalt caulk.

There are many types, and people tend to buy acrylic latex caulk since it is cheaper; however, siliconized acrylic tile sealant is the caulk for tile filling.

So, can you caulk over grout in shower corners? Yes, but this will be a temporary solution. The caulk will peel off sooner than later, or mold will start growing where the crack is.

How Do You Fill Gap Between Tub and Tile?

When we ask designers to include a tub in our bathroom, they should leave a space between the tub and the titles.

The whole house structure moves over time; that is something completely usual and unnoticeable for people.

Moreover, bathtubs expand a few centimeters when people take a bath and fill the tub with water. Then, the space between the tub and titles is indeed needed.

The space between the bathtub and titles is generally a quarter-inch. Experts will leave the intentional ¼ inch gap between both elements; though, for those people who decided to install a bathtub by themselves, a space between ¼” and 1/8” is fine.

Once we had installed the bathtub in our bathroom and had left the intentional gab, we must fill this space up.

When the gap is somewhat between ¼” and 1/8”, you can fill it with siliconized acrylic tile sealant. If the gap is broader than 1/8”, I recommend you fill up the space with sanded caulk.

How do you caulk between tub and tile?

Whenever you are using siliconized acrylic or sanded-based caulk, the process is almost the same.

Caulk can be found in stores, and this has a convenient presentation that makes the caulking easier. So, to caulk between tub and tile, you should follow the next steps:

Clean the area. It is important to prepare the space before applying the caulk in both cases. Clean the area around with a dry cloth or brush to remove any dirt. Dust will make the bonding difficult; the silicone caulk will not adhere to the surface properly.

Prepare the area. Put painter tape strips on the wall and tub borders leaving around 3/8 inch of space between the strips. Try to place them parallelly make a straight line.

Prepare the caulk tube. Commercial caulk comes in a useful presentation. The caulk tube tip can be cut according to the size needed. If you have a caulk gun, place the caulk tube on it. Then, cut the caulk tube tip.

Apply the caulk. This part could be considered the easiest step. Apply the caulk between the painter tape strips, right on the tub–tile joint.

Smooth the caulk. Some recommend wetting one of your fingers and move it over the caulk; this will give that aesthetic curve to the joint and seal the tiles with the tub.

What Happens When You Caulk Over Grout?

If you apply caulk over the grout, and even old caulk, the new caulk will peel off and mold will start growing between one compound and another.

Grout and caulk have different compositions, so they will not bond together properly.

When it comes to caulk, the old one has degraded over time; then, so when you apply the new caulk over the old sealant may bond, but it will crack easier and won’t last as it should do.

The grout porous surface will not allow a proper bond with the caulk. Therefore, the composition of both sealants is different and this prevents the caulk adheres to the grout; as result, the caulk peels off.

Moreover, the grout is water-resistant but retains water, and even when we see it “dry”, this may be wet so mold will start growing over time.

Fill the tile joints with grout

Caulk vs. Grout

As I mentioned before, caulk and grout have different compositions, so they don’t bond well. However, each sealant compound has diverse uses. Caulk is a polymer-based compound, while grout is a sanded or cement-based mixture that requires water to activate its adhesive properties.

Both compounds have variations, and if we want to tile a place in our home, we need to choose the correct composition.

Tiling grout has two variations; sanded and unsanded grout. The sanded grout is mostly made of silica sand, Portland cement, and it contains some inorganic aggregates; while the unsanded grout doesn’t contain silica sand, it is cement-based and has power color pigments.

Sanded grout is perfect for the floor and shower; in contrast, unsanded grout is ideal for bathroom walls, including the shower ones.

In general, grout is used to adhere the tiles to the wall and fill the spaces between the tiles.

Caulk is made of polymers; for tiles, it is a siliconized acrylic base, and it has a more flexible structure than grout.

Caulk is used to filling the gap between the tiles and a bathtub; also, some tile installers use it in the intersection (the joint between a wall and others).


People can use caulk as a temporal solution for cracking, but that is not a definitive solution. After a few months, the caulk must be changed.

Caulk and grout do not go well together, as it was mentioned several times before. Nevertheless, if you want to replace the old caulk, you should remove the whole caulk line.