a method of defining a rib structure within an iso - grid composite component according to an exemplary aspect of the present disclosure includes , among other things , defining a first rib at least partially with a uni - tape ply bundle at a first level , the uni - tape ply bundle including uni - tape plies and a first spacer ply , and defining a second rib transverse to the first rib at least partially with a spacer at the first level , the spacer including a second , different spacer ply , the spacer transverse to the uni - tape ply bundle such that the spacer is interrupted by the uni - tape ply bundle .