Abstract: A method of assembling a two-sided wall on, through and around a preinstalled structural grid, the method including the assembly of planar wall units, each having an outer side and an inner side, the inner side opposing an inner side of at least one other planar wall unit on an opposite side of the structural grid. Interlocking features extend through a space in the structural grid and span from at least an inner side of one planar wall unit to the inner side of another planar wall unit on a same course level so as to support and gauge opposing planar wall units with respect to the structural grid. When installed in courses around the structural grid, the wall units and the interlocking elements create a continuous void between planar wall units to enable structural fill material to be poured therein filling the continuous void from the top of the wall to its base.