Should I use 100% Silicone Caulk Sealant or the Sanded Caulk Sealant?


I have a white subway tile backsplash in my kitchen, counter is granite. Should I use 100% silicone caulk between the two or can/should I use a sanded silicone caulk by the same manufacturer??


ANSWER - The tile and stone industry standards require that an ASTM C920 sealant (caulk) is used for movement joints and transition joints between changing planes or materials.  ASTM C920 are normally 100% silicone or a urethane sealant.

Sanded sealants (caulking) normally do not meet ASTM C920 standards nor do they perform as well or last as long.  Typically sanded sealants are acrylic or latex based and they might say it is siliconized, which is not the same as being 100% silicone.  They are much easier to use for the installer in terms of application and installation, but they don't come close to lasting as long or performing as well.  Installing the 100% silicone sealants requires much more protection and care, and timing of the application is critical to ensure a good installation and easy cleanup.

I have seem some installers broadcast sand over the 100% silicone so it looks more like the grout, but that diminishes the performance of the material and voids the product warranty.

Note that per the sealant directions you are suppose to apply a backer rod or backer tape in the movement joint before applying the sealant, and the sealant needs to be at least 1/4" thick for walls, which isn't practical for very thin tiles.   Per sure to follow the sealant manufacturer's directions.

6 thoughts on “Should I use 100% Silicone Caulk Sealant or the Sanded Caulk Sealant?

  1. Rob H says:

    I used “Custom” brand Sanded Ceramic Tile Grout to redo cracking grout on the bottom of my shower where the floor meets the wall. Do I need to also use a sealer or is the grout enough? The grout is siliconized, but Not 100% silicone

    • Donato Pompo says:

      A sanded grout is normally a rigid cementitious grout and it should never be used at the transition from the floor to the wall.

      You said it was siliconized, so that suggests it was a resilient caulking, but not one that meets ANSI C920. The 100% silicon caulking/sealants do meet ASTM C920 and will last a lot longer. The siliconized caulking will work at first, but they don’t last as long or perform as well.

      Regardless of which sealant/caulking you used, you don’t need to apply a sealer over it as the caulkings in theory are impervious.

  2. Sarah says:

    What about silicone first and then sanded silicone… just for looks? Would that do meet the code requirements?

    • Donato Pompo says:

      I have tried adding sand in silicone and urethane sealants and it doesn’t last long or perform well. And it would not meet the industry standards.

  3. Aaron says:

    Great info! I started to use sanded to patch some cracks and this stopped me.

    I have a shower with marble hex tiles and standard grout. The grout has gotten a bit dirty (I don’t think it was ever sealed), and I was thinking about cleaning, then using a 100% silicone over the old standard grout. Is this a bad idea? Haha. I like the longevity and resistance to mildew/mold that the silicon provides.

    • Donato Pompo says:

      You need to get enough depth in the grout joint for it to be practical to over fill the joint with the ASTM C920 silicone sealant. The grout joint and the sides of the tile have to be very clean. You might need to use a primer first.

      Make sure you use a silicone sealant that is mildew/mold resistant. Don’t use a clear sealant as they tend to darken. When you apply the sealant you should tool the joint slightly to give a slight concave surface so that feet don’t walk on the sealant. This will help prevent the sealant from getting dirty that can be difficult to clean.

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