pressure water treated. wood

Pressure treated lumber with a good stain and seal. Thompson's now have a stain and seal combo that would work well for this. Love this idea.

How do you clean the drain?

I tried this in my home using cedar wood that rested on a frame on top of the tiled shower floor.
We rested the wood floor on a frame so we could remove the wood floor to clean the drain and tiles underneath. Unfortunately this application didn’t work for us. The wood expanded from the moisture and molded quickly despite using a marine finish. I designed our ensuring bathroom around having this cedar shower floor and disappointed we can’t find something that will give us the same cedar look on the floor.

Does anyone know if cumaru can be used for a shower floor?