Is Interior Plywood a Good Alternative to Drywall for a Cabin in Climate Zone 7?

A homeowner building a cabin in a cold climate (Climate Zone 7) asked whether plywood, either 1/2-inch or 3/4-inch thick, could replace drywall on interior walls. The appeal is practical: plywood gives a sturdier surface for hanging shelves and other items, and it skips the taping and mudding that drywall finishing requires.

The real question raised was about moisture. Interior wall surfaces sometimes go over a vapor-retarding membrane, a layer meant to control how much moisture passes through the wall. The homeowner wanted to know if swapping in plywood, which behaves differently than drywall when it comes to moisture, might interfere with the wall's ability to dry out toward the inside or the outside. This matters because walls that can't dry in either direction are more prone to trapped moisture, which over time can lead to mold, rot, or reduced insulation performance, problems that show up especially in cold climates where walls see big temperature swings.

At the time this was posted, the question had drawn only one reply, and it wasn't a substantive answer. So for now, there isn't a clear verdict on whether plywood is a safe drywall substitute in this situation. Anyone weighing the same swap in their own cold-climate home should treat the moisture question as unresolved and worth checking with someone familiar with the specific wall assembly and membrane involved before finishing walls this way.