How does the cross bracing get installed in a wall assembly when the Design specifies “Cross braced at mid-height” ?

Details on cross-bracing can be found in the Supplement to the 1991 Edition of the “National Design Specifications” for wood construction. (PDF Available for purchase from AWC (Click Hear). Most structural engineers are well aware of the practice.

In basic terms, cross-bracing refers to the practice of bracing stud to stud in order to reduce the effective length of the stud and as such increasing the load capacity. In most cases, the bracing is done at the mid-height of the wall as that is the most effective location of the bracing. This may not be the only method specified by the National Design Specifications, but contractors typically use 2 X 4 (or 2 X 6) members spanning stud-to-stud, located at essentially the mid-height of the wall, orientated with the 1.5 in. dimension vertically, offset vertically 1.5 in. between cavities to allowing for nailing. The cross bracing is not intended as backing for horizontal joints of the gypsum board.