Questions & Answers

Hello... I’m tiling a small bathroom floor, it’s only 6’ x 6’, but the OSB subfloor is 1/4” off level. I need/want to use 1/2” hardibacker to best match the flooring of the adjoining room. I’m stumbling on how to level this floor.

I am installing mosaic tiles so I don’t think I can just install the hardibacker as-is and then build up my thinset an extra 1/4”, it would probably come up through the grout lines (I’m using Multimax lite).

And if I put self leveler or patch BEFORE the hardibacker, let it dry, and then thinset before laying down the boards, the screws would crack the SLC and create crumbs (one guy said it sounded like cracking granola when walking over it 🤣)

Another approach is to first thinset in the hardibacker, then self leveler, let dry, then thinset the mosaic tiles over that, but then that defeats the pink, water-resistant hardibacker, since the self leveler would absorb water (the bathroom is for a young child and there’s a bathtub with a lot of splashing).

Lastly, I’m thinking to use Multimax Lite to thinset in the hardibacker, put an extra 1/4” of thinset in the low areas (use a 1/2” trowel in the low areas and a 1/4” in the other areas), and then screw down the hardibacker, being VERY careful to not over-tighten the screws and squeeze out the thinset. However, then I will worry if I’m getting full coverage since I’m only lightly pushing the hardibacker down.

So… what to do?

thank you