I had a phone call recently from a very knowledgeable contractor whom I have known and respected for many years. He had been presented with an opportunity to do a large commercial quarry tile project. For a contractor, it doesn’t get any simpler or better than lots of 6” x 6” quarry tile unless you throw in some 4-1/4” wall tile, then that is truly heaven. Problem was, this is a manufacturing facility with a failing epoxy floor coating causing potential health issues (think peanuts). They do not want it removed and they are not shutting down production to put the floor in so you have to work under the running equipment. This job had bad (with a capitol “b”) written all over it. No matter how attractive the job is or how great the need is, does anyone really think this job will be profitable? If so, then you’re not staying in business very long. Is it possible? Yes, minutely. Probable? No. Let’s take a look at some things that have and have not changed about tile installation.
That the epoxy floor coating is failing says either the surface was either improperly prepared or it was contaminated when it was installed. Or, there is excessively high moisture levels in the slab from whatever source, which, when covered by new tile, will cause further release with the tile attached.
One thing we can be reasonably sure of, even the well-bonded areas of the epoxy coating will not be so well-bonded once it is covered with quarry tile, grouted, and hosed down three times a day. There is a reason the coating let go in the first place and covering it up won’t make that reason go away. In this instance, as in most, the coating needs to be removed before the tile goes in, as it should if it were any type of adhesive, paint (including overspray) or coating such as curing compounds.
The slab surface, which should be visible in the failed epoxy coating areas, can provide some indication of what the surface looks like. If it is nice, flat, and shiny, either by means of hard steel troweling or coatings, then the slab will require either removal or abrasion by mechanical means to roughen the surface and assure an adequate bonding profile. Thinset does not like to stick to shiny surfaces. The more demanding the in-service conditions of the floor, the greater the concern should be. In the case of a commercial processing plant, the in-service conditions are certain to be severe.
For this project, the selection of quarry tile is a good one as there are several drain areas with substantial pitch in the floor to accommodate. A 6”x 6” tile can be used on nearly any reasonably flat surface and will tolerate a little undulation in the floor. If the selection were a larger size tile, then there will be additional floor-fill required. It is, and always has been, unreasonable to think there is not going to be some floor remediation with any tile job and I’m sure this one would prove no exception. The time to flatten out the floor is before you start the job, not with thinset as you install the tile. As tile grows larger, we’re seeing more and more installers building up the floor tile with thinset.
There have been several instances recently where I’ve been involved in figuring out what went wrong and found regular thinset built up over a 5/8”. In one instance it was the cause of failure. As it shrunk, which all thinsets do, it pulled the membrane it was bonded to right up off the floor - creating a hollow sound in various areas of the installation. In the other instance, it was used as large dots to level out the tile over the previously notched floor.
Once we get through the leveling and setting, now comes time to grout. A food manufacturing facility just screams for epoxy grout. Use of any tile floor where food and beverage processing or preparation occurs will always benefit from and should use epoxy grout. Even residential areas can benefit from it though they are much less susceptible to the bacterial growth that occurs in a commercial application due to less exposure.
Cement grout is porous. Even the perfectly prepared and installed cement grout joint has porosity in the plus or minus 10% range. That means that it has the ability to hold 10% of something within the pore structure of the grout. If that is foodstuff, once decomposition starts and it turns acidic, the grout’s demise has begun. Anyone who has installed tile in fast food or commercial kitchens can tell you with rare exception, cement grout doesn’t last long.
Before we move off the epoxy subject there has been a new development that is noteworthy. Recently, there been an increased popularity of “no rinse” cleaners in commercial environments. Without going into a big chemistry lesson, some have a very negative effect on epoxy grouts. Manufacturers have come up with new formulations that are resistant to the chemical reaction that occurs with use of no rinse cleaners. Along the same line, the one complaint we have consistently run into with epoxies is that they soil. The reality is that an epoxy joint, being impervious, does not allow the passage of water or contaminates through the joint - they must be removed, not rearranged. That requires a higher level of maintenance than someone who is accustomed to cement grout has experienced. Creating an awareness of these issues can save headaches down the road. There are many different types of epoxies available. Some are better at specific tasks than others, but none of them are cheap. Chose wisely.
Neither epoxy grout and certainly not cement grout constitutes waterproofing. Just a few weeks ago, I reviewed an engineering report where the determination had been made that a floor failure occurred because the water passed through a grout joint of inadequate depth due to thinset buildup. While it sounds plausible, his client was a little hesitant of the findings and investigated further. This is a widely held perception by many, that somehow grout constitutes waterproofing. While cement grout will reduce the amount of water penetration and epoxy grout will hold back even more, it is unlikely any installation would be fully waterproofed by grout alone. That requires a separate waterproofing system that’s to be used during the installation.
Remember, if you’re going to stop the water, it does need to go someplace as well. That’s all the space we have for this issue. As always, your comments and ideas for future articles are welcome.