Frame the wall with minimum of 4" x 2" timber or 20 gauge metal studding @ 16" centres. Noggins to be placed at the end of each board wether you fit them horizontal or vertical. Keep a clearance of 1/4" from floor, bath, shower ect. and seal with a Silicon. I personally like to leave a 3/8" gap all round each board & seal with Silicon to allow for movements in the timber framing.