I was planning on putting caulk around the base of my bath/shower, but I have been told by someone that it is preferable not to seal the bottom of a bath as it "prevents it from being able to breath" (which I assume, but don't know for sure, means they are saying any moisture under the unit will not be able to evaporate).

However, to me this seems counter-intuitive. If the bottom was sealed, that would prevent an obvious route for moisture to get under the unit.

The bath is fiber-glass, against a tiled wall which the shower head is mounted to. The flooring running to the edge of the base is linoleum.

Should I seal or shouldn't I?

  • Can you describe what type of shower you have? Is it glass, tile, fiberglass, etc? Do you know what's behind the shower, such as a waterproof membrane?
    – BMitch
    Aug 8, 2012 at 13:16
  • @BMitch: I've edited the question with more information, but the bath is fiber-glass. The shower is just mounted to the tiled wall above the bath. I don't know if there is a waterproof membrane behind the bath.
    – Lauren
    Aug 8, 2012 at 13:22

1 Answer 1


I would caulk any joint between fiberglass and tile. Some pre-made fiberglass kits have ways to overlap and seal the joint, but that doesn't appear to be your situation. Water coming out of the shower will be much more significant than any moisture that makes it through the tiles and grout.

That said, if moisture eventually deteriorates the walls and tiles, the best option is to replace the wall and then use a waterproof membrane that prevents any moisture from getting to the wall.

  • 7
    Always run a bead of silicon caulk around the base of a tub or shower. This prevents water from seeping under the fixture and causing problems later on, like a rotted floor or mold. In over 30 years in the business, I have never heard of letting the bottom of a tub/shower "breath". Aug 8, 2012 at 13:29

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