Hi guys & gals.....

I am in the process of doing some work in one of my bathrooms. I plan to install bead board (not the panel type)as a wainscot. My walls, once I removed old paneling and tile board, are solid wood on the studs. The boards are about 11" wide and most likely long leaf pine 3/4" thick. I am removing these wall boards where the bead board will be installed so that the bead board is flush with the remaining wall boards above. I am assuming that I will need to install some pieces of 2x4 between all the studs to have something to nail the tongues to.....is that correct? If so, from the floor up, what should the spacing be?