You’ll notice that we are re-installing the pine on top of the Sheetrock. That’s critical in my opinion. Wood is terrible for air infiltration and for sound reduction. Drywall is cheap and you only really need to finish it to a tape coat before installing the wood overtop.
Biscuits are a finish carpenter’s secret weapon. We’ve loved this DeWalt Plate Jointer (Biscuit Jointer). Anytime two board butt we typically biscuit the joint.
Titebond 2 is our favorite wood glue. My guys keep a 16oz bottle in their tool belts at all times. Glue is the secret to joints not opening up over time. Use it liberally in your wood wall installations (or any finish carpentry project for that matter).
We ran two kerf cuts with our circular saw across the backside of these pine boards to help encourage the boards to never cup.