I didn't read the whole blurb but it looked to me like that is for keeping moisture from going throught the porous tile and damaging the sub strate as in a tile over wood framing. It does not sound like it applies in your case.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.