A rack construction assembly for building a storage rack includes a plurality of bracket units. Each of the bracket units has a plurality of channels therein to insertably receive dimensional lumber. Thus, the dimensional lumber is arranged to form a rack for storing objects. Each of the channels corresponding to each of the bracket units is oriented at right angles with respect to each other. Thus, the dimensional lumber corresponding to each of the channels defines an X axis, a Y axis and a Z axis of the rack.