Are my tiles bonded properly in my Steam Shower?


We are installing a new steam shower and had these concerns about the tile work. (1) We had learned he used sanded grout and have someone new who is removing it to re-grout with epoxy. (2) When the new worker removed a few tiles damaged in removing grout he discovered the tiles popped right off the wall and we all saw the strange way the tiles were mounted to the wall.

Can you tell us if this is some version of Spot Bonding? Can you give us some feedback? If it is Spot Bonding, don't we need to have the tiles re-installed before we re-grout with epoxy grout?
We appreciate any assistance you can give. We want our new steam shower to help us be more healthy, not to make us sick!


ANSWER - First of all there is nothing wrong with using sanded grout as long as the grout joint width is 1/8" or wider.  There are some benefits to using an epoxy grout in terms of stain resistance and maintenance.  Although, if the epoxy grout isn't installed correctly with an experienced installer the grout can cause more maintenance and be less appealing aesthetically.

To remove existing grout is not an easy process and there is always the risks of damaging tiles during the grout removal process.  We normally expect tiles to be tenaciously attached to their substrate.  Although the standards only require a shear bond strength of 50 psi.  If the tile is pried off the wall then it is being subjected to both shear and tensile stress through leveraging that can be beyond what it can resist.  So it isn't clear whether the tile is bonded adequately or not.

Your link to a photo didn't work, so I can't see if the tile appears to be spot bonded or not.   For shower applications the standards require that there is 95% contact between the back of the tile and its substrate.  In theory, the less adhesive contact the less the overall bond strength.  Today's thin-set modified mortars can reach over 300 psi bond strength.  So even if there were only 50% contact, it would meet the bond strength requirement, although it would still not meet the thin-set contract requirement.

It would be best to verify whether your tiles are bonded adequately or not before you re-grout with epoxy.  You don't want to spend the money on re-grouting only to have to then deal with a tile debonding problem.  The only way to accurately determine if the tiles are bonded well enough is to test them for their bond strength.  You should hire a forensic tile expert to evaluate your situation, although the cost for doing so may or may not be prohibitive and not practical for your situation.

2 thoughts on “Are my tiles bonded properly in my Steam Shower?

  1. Ahna Barefoot says:

    Thanks for the timely reply. (1) You mentioned using sanded grout in a shower. But, just to clarify, we are installing a STEAM shower, and all our research has advised to use epoxy grout in a steam shower. We have corresponded with a grout company who recommends epoxy and said only use sanded grout in a steam shower IF it is subsequently sealed (and repeatedly sealed) so the steam does not penetrate the grout–and we were concerned how you would always notice in time to re-seal it. (2) After two tiles were removed to replace them, a gentle tap on the others and they fell down leaving the 4-inch spots of mortar still on the wall–obviously the tiles were not securely attached with mortar. Also not a single corner was secured on any tiles. (3) Also, the new tile installer discovered the 1/16-inch joints did not allow for tile expansion in a steam shower. The end result is we are re-installing the tile in the steam shower, and we think you would agree it is necessary. Correct?

  2. Donato Pompo says:

    The industry standards do not require using epoxy grout in steam showers. Sanded and non-sanded grouts are typically used in steam showers. Regardless of which type of grout is used the steam shower has to be properly waterproofed and vapor resistant to have less than 0.5 perms vapor transmission. Manufacturers of grout make a lot more money when selling epoxy grout versus cementitious grout, so they have an incentive to promote epoxy grouts. Epoxy grouts can add some value if installed correctly in terms of lower maintenance and making the grout joints more water tight.

    Standards do allow for 1/16″ wide grout joints, although it is better to have at least 1/8″ wide grout joints or larger to to fill the grout joints. It is unlikely that the coefficient of expansion of the tile in a steam shower is great enough to be problematic in terms of contraction and expansion of the tile, but it depends on what kind of tile you are using and whether you have proper movement joints installed at the various transitions. Using an epoxy grout is much less compressible than using a cementitious grout, but that should not be problematic for a steam shower application.

    Don’t have enough information to determine whether or not the tile needs replacing. If in fact the tiles are falling off with a gentle tap, then that is a problem.

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