Why do you want plywood? It will delaminate. It will get moldy. It is not waterproof.

Why? It's beautiful https://www.pinterest.com/naomirherzog/plywood-bathroom/?lp=true The wood will be fine if you treat it right. Wood is very commonly used in Japan. Think Sauna.

The wood will not be fine. It will delaminate. A sauna is an even worse place for playwood, period.,

Ok thanks.

The complete lack of connection to reality of the Pinnterest-addicts strikes again.

If you want wood in a bath, it needs to be a rot resistant species, like mahogany or teak solids. Not cheap ply that won't make it a year.

Plywood is several layers of wood, laminated together. It may swell too much for the use you are thinking of, but I am no expert in using it, so I do not know if that can be fixed by coating the surface and ends with something like Waterlox. I am hoping that you will get more answers.

I do know that plywood is preferred over MDF for quality cabinet sides and backs. It is also commonly used on the front, with a layer of a preferred wood veneer for the top layer. My carpenter made my bathroom door and drawer fronts out of birch plywood with a walnut veneer. Then he Waterloxed them. If you are using the plywood as a wood paneling product in a bathroom area not directly in contact with water, why wouldn't it work as well as my drawer and door fronts?

Then there is the question of using quality wood paneling. Are there types or brands that are appropriate for bathroom use? Lets hope others come by and give you more opinions.

Yes, I will be using a hardwood variety of plywood.

Plywood will be fine. Use a good grade of exterior plywood and clear coat it. You could use epoxy if you wanted for overkill (and marine ply), or some marine varnish. Seal all the edges and sides before you install it. People make boats out of plywood, and many other exterior projects are built with ply. I'd install a baseboard and rest the sheets on top of that to keep it off the floor.

Thanks so much!! Can I put it over the existing wall? It's drywall.

Even with marine grade plywood, I'd be concerned about moisture sorption at the joints. Humidity control (i.e., a properly sized vent fan) will be extremely important as will sealing all exposed wood including the cut edges at the joints. That said, I'd play it safe and choose an alternative material.

All edges of plywood would be fresh cut and sealed beforehand for sure and then entire wall sealed again. The house is in the desert. Very low humidity there but yes, a proper fan for sure.

Your inspiration pix are of regular softwood (not hardwood) plywood. A Grade.

Using it on the walls is no different than having cabinets built of plywood in the bathroom. Plywood is reasonably dimensionally stable so really not much concern about dimension changes.

1/4" plywood will be plenty thick enough. Use glue (Liquid Nails, etc.) and nails. Sand and seal it, of course. As long as it isn't standing in water, you don't need to be concerned about delamination of ply on the walls any more than you need to be about plywood cabinets delaminating.

Hello! How about sending us some pics of how your bath turned out?!

@Los Feliz Girl How did your project turn out? I would like to hear about your plywood journey, as I am really in love with the material myself.