For chapters 2.19 through 2.23 in Chang’s “Building Construction illustrated” we are introduced to three key elements when thinking about the design and construction of an inclosed space. The first being structural Units and the two dementions which defines it; Horizontal span (which should consist of either reinforced concrete, slabs, gurders or planks) and Vertical support ( consisting of loadbearing walls, columns and beams). The second topic (Structural patterns) dives into the purpose of creating a grid that aligns with the functionality of the structure; which ultimately will determine the placement of the columns or load bearing walls according to the critical points or intersections within the grid. The third point made by chan is Lateral stability, which should have one of the following constructions; knee bracing, k brace or cross bracing in order to better  avoid destructive torsion.