The right side of the bathtub touches the wall which has tiles. There is a small gap between the bathtub and the tiles.

I fill this gap with silicone but it comes off after a few months. I have tried many different types of silicones. They last on average for 6 months.

The other silicones in the bathroom do not come off. It is only this specific portion that has the problem because it gets lots of water directly from the shower.

I am just looking to see if there is a permanent solution to this problem.


3 Answers 3


Bear in mind there are different modulus silicones. (Meaning "modulus of elasticity" -- how stretchy/flexible the silicone is.) Could it be you have used a low modulus silicone, which has moved beyond its flexibility limit as the tub has flexed?

If there is even a slight movement, use high a modulus sealant. Use a trade brand.

Otherwise, I agree with crip659's answer: remove old sealant, clean really well, allow to dry really well, and do use alcohol. Leave time to fully cure.

The purpose of filling the tub is to ensure the sealant is applied in its most extended position. After curing, let the water out, and it will sit under compression (because the tub will relax).

Full curing may be up to a few days if you have a deep fill. (The surface will skin quickly, but it leaves a semi-liquid interior that takes much longer to cure.)

If the tub moves substantially vertically, then you might check its support (such as for a rotten or broken floor board underneath, or perhaps a support that is not well adjusted).

  • Clarification: "modulus" here means "modulus of elasticity" -- how stretchy/flexible the silicone is. (You might want to edit that back into your answer; comments on Stack Exchange are not considered permanent and may vanish for various reasons, some of them legitimate and some just quirky.)
    – keshlam
    Commented May 22, 2023 at 8:58

The most common reason for this is the surfaces are not cleaned first.

Remove all old caulking completely.

Clean the surfaces, water and soap at first and maybe even wipe down with alcohol.

Fill the bathtub with water, and caulk around the edge. Use caulking made for bathtubs.

Let caulking set and then drain the tub. It should last.

  • Could it be from the tub moving from person's weight? I have a similar issue with the side that's opposite the side you step over, and I noticed it moves a little when I get into the tub. I am guessing it's due to the material the tub is made of. Commented May 21, 2023 at 17:42
  • 2
    @montrealist Maybe, one reason to fill the tub with water first. The tub sinks down a bit before the caulking is added.
    – crip659
    Commented May 21, 2023 at 17:58
  • 1
    And if the silicone still doesn't work, try a poly like OSI Quad Max.
    – Huesmann
    Commented May 22, 2023 at 11:52

Some of this depends on what you mean by "silicone". There's two possibilities

  1. Pure silicone caulk. Mineral spirit cleanup and stinks like crazy
  2. Siliconized latex caulk

Most likely you're dealing with #2. Latex caulk is a water-based cleanup, so it breaks down more readily. This type of caulk will indeed not last a long time. Cleaning and drying the surfaces here is important, or the caulk won't adhere properly. Even with proper adherence, expect any latex caulk (siliconized or not) to not last a long time.

Pure silicone caulk is a different beast. Make sure you ventilate well and have some mineral spirits on hand. This stuff smells like crazy but it lasts a long time. If you're tired of your latex, this can resolve your problems, but once it loses adherence be prepared to cut it out before applying more.

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