Is there anything in writing you can provide regarding use of red body ceramic tiles as shower floors? I generally don’t recommend high water-absorption products in showers. I realize the glazes are impervious, but I have seen failures when the body of the tile has a high water absorption >7% and in some cases >10%. Is this addressed anywhere in the NTCA guide either for or against it?
I discussed this with several members of our technical team. As you and I also discussed on the phone, we are not aware of any item in the industry standards, including ANSI A137.1, ANSI A108, the methods and best practices found in the TCNA Handbook or the NTCA Reference Manual that describe whether it may be acceptable to install a red-bodied ceramic tile in a wet area such as a shower floor.
The best basis we have to go on is whether this is a floor tile and whether the manufacturer recommends it for installation on floors in wet areas.
Also, it may be important to consider whether the type of shower pan this entry-level-option shower floor tile will be installed on is water-in / water-out (thick-bed system with a liner and pre-slope i.e TCNA Handbook Method B-415) or if the tile will be installed on top of a sloped pan with a surface-applied membrane. If it will be installed on top of a surface-applied membrane, it is important to
consider whether the draining water may be absorbed by the body of the tile as it percolates through the grout and into the bond coat and body of the tile as it makes its way to the surface-applied waterproofing layer. I do not know for certain if this will lead to an issue with bond or performance of the tile or of the system.
I ran your question past a Recognized Consultant for a quick opinion. Here is the slightly paraphrased answer: “In a perfect world, it would work, but I wouldn’t do it. Soft absorbent body, unforgiving of installation error, glazed surface. I don’t see any cost savings. Why not a cheap porcelain? Wet is one thing; soaking absorbent tile in soapy water is another.”
– Mark Heinlein,
NTCA Training Director
Mark Heinlein is Training Director for the National Tile Contractors Association. He is Certified Tile Installer #1112 and currently a Ceramic Tile Education Foundation evaluator for the Certified Tile Installer program. Heinlein was the owner of Mark Heinlein Surfaces of Negaunee, Michigan.