PT Lumber used for walls

[Sean DIYer]

Okay...not sure if I should throw up now or later, but I just read that you should not use PT lumber for walls when you tile. I butted PT 2x4's up next to the existing 2x4's (Non-PT) in my shower prior to tiling becuase of water damage. I chisled out the rot and sealed the old 2x4's. I have have installed a shower pan and stared tiling the walls. The PT 2x4's have been in the walls for about 5 months prior to putting up hardibacker and tile. I'm feeling a bout of nausea...how bad is what I have done?

Thanks,
Sean

[ddmoit]

Only time will tell, Sean. There's really nothing to do now but wait and see. Maybe nothing will happen.

Pressure treated lumber is proscribed in shower construction because of its tendency to warp as it loses what starts out as a pretty high moisture content.

Put it out of your mind until cracks appear, which may be never.

[xxPaulCPxx]

Another thing besides warping to worry about is fastener corrosion. Unless you put it together with SS nails/screws or some really thickly coated zink fasters, you might have little spears of rust where you fasteners used to be.

[jadnashua]

After 5-months inside a typical house, the boards have dried out and other than the fastener issue, probably won't be an issue. It becomes a big problem if they are enclosed so they can't dry out, or if they repeatedly get wet then dry out. Hopefully, yours should stay dry. If you do choose to use pressure treated, look for KDAT, kiln dried after treatment. Those should be as stable as "normal" studs.