I want to install 3/4”x 6” tongue and groove pine wall plank on the my interior walls instead of gyp board. The IRC doesn’t specify whether or not tongue and groove wall planks are an “approved material” to replace gypsum wall boards as part of a braced wall line. I asked the Eng and Arch and they don’t know either. They just said well the braced wall line was designed based on gyp on the interior. Seems pretty stupid to install 1/2” gyp and then the tongue and groove planks. Anyone have experience with this issue?