We're about to embark on a total bathroom refurb and my wife wants to install marble mosaic tile flooring like she saw on a DIY show. What I need to know is what type of underlayment system is recommended for a pier and beam foundation with 2x6 T&G subfloor over 4x6 beams 48" O/C? The tiles will need to transition to 1/2" solid wood flooring in the bedroom so I want to keep the height to a minimum. Oh yeah, and she wants to but a freestanding tub on top of it, too! You think any of this is possible?
No, it's not possible if you wanna do it according to industry specs. You're most likely located on the left coast where that kind of construction is fairly common. There's no spec that allows framing any wider than 24" o.c., and then you have to add more plywood too.
You should speak with some locals and consider something other than natural stone mosaics. A claw-foot tub isn't such a good idea either, but flat bottom tubs should be ok.
TILE GUY - retired- TROY, MI - Method & Product suitability consulting.
I have a similarly framed floor but with 1 and 1/8 plywood on top instead of the 2x6. I had the same concern about tile so I had my contractor go in the crawlspace and put a diagonal 2x4 between the two joists, 1 running underneath each bathroom (diagonal across the underside of the floor). Had marble tile for 3 years and no cracks (just 1/4 inch cementous board underlayment).
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