CTEF Tile Tip: Poor Floor Prep Leads to Tile Failure
The success or failure of most tile projects is proportional to the amount of floor prep provided and how much attention to detail was paid. When corners are cut to save time and/or money on a job, the result almost always results in failure.
The job in this case is a locker and shower room. The floor being replaced was medium-quality, low level loop carpet which stopped approximately 24 in. from the four stall showers in the room. Over time, the almost always wet carpet caused a less than desirable odor and unhealthy situation. The sensible solution was to replace the carpet with a low maintenance, hygienic ceramic tile.
Bids were taken on the job, and as you can guess, the job went to the lowest bidder—who removed the carpet while leaving a reasonable amount of latex adhesive bonded to the concrete floor. Most times you would think the well-meaning contractor would remove the residue and use a high-performing latex-modified thin set mortar to bond the new large format tile.
Unfortunately, in this case, none of that was done. The remaining carpet glue was left on the floor, over which the tile installer used the least expensive mortar locally available. These two factors are bad enough, but the scenario gets worse. The installer used a 5/32 in. V-notch trowel to bond the large-format tile, which did not provide anywhere near the required 80% mortar coverage. However, this room being adjacent to constantly used shower stalls should have made it a candidate for 95% mortar coverage.
Now enters problem number four. The room contains two saw-cut contraction/control joints in the concrete No effort was made to treat them with a crack isolation membrane; instead the tile was installed directly over these joints, unprotected. Additionally, there were no expansion joints in the tile at the saw joints or along the perimeter walls. Now fast forward almost three years. The floor is hollow and completely unbonded to the concrete slab, with cracked tiles on the horizon.
This is a prime example of the lowest and least qualified bid costing the commercial customer significantly more money than the lowest “qualified” bid. As the TCNA Handbook states in the Installer and Contractor Qualifications Guide, “Because tile is a permanent finish, the lowest bid should not be the driving factor, but rather who is the most qualified to perform the scope of the work specified.”
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