Not All Tile Is Made to the ANSI Standard: A Hidden Cause of Bond Failure

​During many recent inspections of hollow and thin-set tile installations, I've come across numerous cases where the thin-set was not bonded to the tile itself, but was instead solidly stuck to the concrete or matting system beneath it.
ANSI stands for the American National Standards Institute, and not all floor and wall tile is manufactured to the ANSI standard. Even though we, as inspectors, use ANSI and TCNA (Tile Council of North America) guidelines as our reference points, not all tile is produced to meet them.
How do we know this, or what can we use to test for it? If an attic stock of the same dye lot is available, simply turning the tile over to expose the back while performing a warpage test lets us also run a water absorption test — the same type of test used for concrete — to check the absorption rate of the tile's bisque.
When doing this, if the water absorbs into the tile in less than 20 seconds, we know the tile is highly porous. When this is raised with thin-set manufacturers, they point out that this rapid absorption pulls water out of the thin-set, preventing it from bonding and hydrating properly.
The result is that when the tile is pulled up, the thin-set is left stuck to the concrete but not to the tile. What can be done about this? If the issue is identified prior to installation, wetting the back of the tile before setting it will prevent the thin-set from being excessively dehydrated. Setting a dry, highly absorptive tile directly on top of the thin-set draws moisture out of it, resulting in a weaker bond than what is recommended.
As a home settles and substrate movement occurs, we often see hollow spots and tenting of the tile that would not have happened if the tile had been properly bonded from the start.
So who is at fault? The manufacturer will claim it did not produce the tile to the TCNA standard, so it bears no liability. The distributor purchases the tile but doesn't test it for absorption before selling it — are they responsible? Or is it the installer, the last person to touch the tile, who bears the blame?
Like many other construction problems, the flatness tolerances of Division 3 (measured with FF numbers) and Division 9 (with its standard of 3/16 in. over 10 ft.) raise questions that remain unanswered. As an inspector, our job is to identify the problem. In this case, I can point directly to the tile's high absorption rate as the cause of the defect and the resulting failure of the tile installation.