Bob Vincent, FDOH:  The DOH does not object to today’s interpretation.  In the future FBC code revision, this Dec Statement should be included in the FBC as code, preferably with a standard for pool tiles such as the Voluntary Product Std for Softwood Lumber cited in the Nominal Size (Lumber) definition of FBC Chapter 21, where the standard cites nominal and dressed (surfaced) lumber sizes. Tile and grout mins and maximums could be addressed.
The size limit and adhesive requirement for 1x1” pool tiles was implemented in the 2009 DOH rule 64E-9, Florida Administrative Code, after vitreous (glass) tiles on public pools were found to have lost adhesion and fallen off in relatively short time frames (see photo examples).  During rule promulgation, industry representatives stated that 1x1” minimum size tile was sufficiently large to assure sufficient adhesion for long terms when a specified strength adhesive was used.  Tile loss on a pool wall creates a ready surface for microbial growth that is difficult to clean, allowing harborage in biofilm for human germs, and has been found with sharp edges that are potential injury hazards.