How to Prevent Mold on Tub and Shower Caulk

I’m constantly replacing the caulk between my shower walls and floor due to mold. How can I prevent mold from forming on the caulking in my shower? -Bill

Hi Bill,

Any time you put caulking in a high moisture environment, such as in a shower or tub, the result is usually mold and mildew. One thing I always recommend is to use 100% silicone caulking in a tub or shower, rather than acrylic caulk. The caulk you use in a tub or shower should also contain a biocide to prevent mold from forming.

While several manufacturers have come out with pretty good mold resistant caulk, I’ve really been impressed with GE Silicone II* K/B Supreme.

Advantages of GE Silicone II* K/B Supreme include:

  • Cures Fast: Can be ready for use in as little as one hour and no more than eight hours (depending on temperature, humidity, and size of the bead).
  • Mold-Free: Contains a biocide that keeps the caulk mold-free for 10 years, if the caulk is cleaned regularly.
  • Waterproof: 100% silicone caulk is and remains waterproof over time.
  • Flexible: 100% silicone caulking doesn’t crack or shrink and remains flexible over time.

Good luck with your project,


Further Information


  1. On today’s show, 9/10/13,Danny renovated his own bathroom. When the shower was completed, he sprayed the interior with a product that prevented mildew. What is this product and where can I find it? My family just built a house and I would like to treat our showers with this product before the mildew creeps in. Thank you, Liz K.

  2. Hello. What would be the best product to repair or replace the grout joint in our ceramic tile shower where the wall meets the floor? It has a couple of spots where there is about an inch or two of grout missing.
    Thank you.

  3. I have used the GE silicon caulk for years, but their GE Silicon II Supreme is not what it used to be. You should not recommend GE caulk. I have had to replace their Supreme mold resistant caulk twice in 4 years due to mold. I have removed and replaced miles of caulk over the years and this caulk is not mold resistant at all.
    We squeegee our shower after every use and clean it religiously every week and yet the GE caulk randomly develops black mold spots in the white caulk. The first time I used it in 2009 it never dried and they said the caulk was too old, which I bought from Home Depot and they refunded it. I re-bought it at different store and in 2012 – less than 2 years I had to replace it due to mold. In 2014 I replaced it again, then again in 2016.

    I have used extreme efforts to clean and dry the shower base prior to installing new GE Supreme caulk. I even used alcohol prior to installing it per instructions from a pro. Now it is molding again. The caulk is not mold resistant and certainly not 10 years, so I am done with GE. I am now trying DAP silicone caulk with Microban and will let you know how mold resistant it is, but in the past I would get at least 6 to 7 years out of a good caulk job.


Please enter your comment!
Please enter your name here