PT lumber when there is contact with concrete
I have always gone by the rule of using PT lumber for framing or furring when there is concrete on one side.
I now have a bathroom shower where two sides are concrete exterior walls (which I have used PT furrings), and one side is an interior wall with standard 2x4 studs.
I will be attaching cement board over the three sides of the shower before tiling.
The question is, the one side where I have standard 2x4 studded wall, can I hang the cement board directly over it?
If I did that, aren't those non-PT stud faces coming into contact with concrete (cement board)?
Do I need to furr out this studded wall with PT furring just because of this?