In Ching’s long reading of the chapters, he first discusses the different types of arches. He tells us the components of the arch such as the Keystone, which is the center top of the arch. He defines the arch as two or three courses of rowlocks, in addition to the skewback stone, which is a sloped face stone that lies where the arch rests on the vertical componant to complete the form. Furhtermore, Ching moves on to explain the wood joists as the essential subsystem of construction. Between the ceiling and floor finish, a cavity may be present for mechanical functions. His rule of thumb for the depth of the joists is SPAN/16. The types of beams he mentions in his book are box beams, spaces beams, built up beams, and flitch beams. His rule of thumb for their span is SPAN/15 and width is 1/3 or 1/2 of the span. The spans can either be Simple, double, or continuous. For steel web joists, the K series act as zigzags of bent steel beams whin can span at 4 to 6 inches on masonry and 2.5 inches on steel. To create the grid, vertical steel beams can be spaced at about 2 to 10 feet and the horizontal beams underneath can be 24x its depth or less.