1/4” Hydro Ban Board below porcelain tile

[Novice DIYer]

I am leaning towards choosing a 1/4” tile underlayment for my bathroom’s remodel. A Laticrete representative advised that 1/4” Hydro Ban Board can be used on the floor as an alternative to 1/4” cement board which I verified in its spec sheet (linked below). I see this as a pro given it is lightweight (compared to cement board) and easily cut with a box cutter/utility knife. The only cons obvious to me are its cost per sheet and the cost of Hydro Ban waterproofing membrane.

I can find no videos or discussions or even reviews by anyone using it under floor tile. It seems straight forward to use per its TDS - process is essentially identical to cement board, including waterproofing seams and screw heads.

Anyone have experience using it as tile underlayment over OSB or plywood (rather than concrete) and can provide any feedback for floor tile underlayment from a functional and install perspective (i.e. cons, lessons-learned)?

I would also appreciate links to discussions and any video links of installations over OSB or plywood subfloors.

Hydro Ban Board TDS:

https://cdn.laticrete.com/~/media/product-documents/product-data-sheets/lds0400_hydro-ban-board.ashx

 

[Jadnashua]

When using a cbu, or similar panel on a floor, the thinset used is there primarily as a filler, the fasteners hold it in place. The goal is 100% full support through the panel to 100% coverage on the floor. A true cbu tends to be stiffer, so may be easier to get the thinset ridges to smush to a flat surface versus the slightly more flexible panel. Wedi panels when used on a floor don't even require fasteners, but are more critical about the thinset used.

I'm a fan of using a slant-notched trowel with larger tile and panels...it gauges the thinset the same way, but has taller, narrower notches, that after passing over, those towers fall over on themselves essentially filling in the notches, leaving a much flatter surface rather than square, V, or U shaped channels with what amounts to voids in between. It's all about getting the thing embedded properly into the thinset.

Unless you want or need the area to be waterproof, a regular cbu works. Keep in mind that unless there's a dam on the doorway of the room, and you waterproof up the walls, if you get enough water on the floor, it will find its way into the structure, so just having the flat waterproof doesn't buy you much of anything.