The architectural division includes drawings, such as floor and roof plans, interior and exterior elevations, millwork, door and window schedules, finish schedules, special architectural treatments, and nonstructural sections and details. For a discussion of these drawings, you should review chapter 10 of the EA3 TRAMAN.

The structural division is comprised of all of the drawings that fully describe the structural composition and integrity of a building or structure. Included in the division are the foundation plan and details; floor, wall, and roof framing plans and details; reinforcing plans and details; beam and column details; and other such structural plans and details. In a set of drawings, the first sheet in the structural division also should include, when applicable, roof, floor, wind, seismic, and other loads, allowable soil bearing capacity, and allowable stresses of all materials, such as concrete and reinforcing steel. Again, you should review chapter 10 of the EA3 TRAMAN.

The mechanical division includes the plans, details, and schedules that describe the heating, ventilating, and air-conditioning (HVAC) systems equipment and installation requirements. Well discuss more about these systems later in this chapter. The mechanical division also includes plumbing drawings that show the fixtures, water supply and waste disposal piping, and related equipment that are to be installed in a building. The drawings include plumbing plans, riser diagrams, details, and fixture schedules. Remember, that in the order of drawings, plumbing drawings always follow the HVAC drawings. As you recall from your study of chapters 8 and 10 of the EA3 TRAMAN, a plumbing plan (or layout) is a plan view of the fixtures, lines, and fittings to be installed in a building. For an uncomplicated building containing, lets say, one water closet and one lavatory, you can easily prepare a plumbing plan that can be clearly interpreted by the planners and estimators, inspectors, or other users of the drawing. For such a building, the plumbing plan might well be all that is

Figure 4-2.Riser diagram for waste and soil piping.

needed to install the plumbing system. As the complexity of the building plumbing increases, however, your ability to describe the plumbing layout accurately and clearly using only a plumbing plan diminishes. This can easily lead to misinterpretations by the users of the plan. In such cases as this, it is common practice to supplement the plumbing plan with riser diagrams.

The most commonly used type of riser diagram for plumbing is the isometric riser diagram. As you see in the examples shown in figures 4-1 and 4-2, the isometric riser diagram provides a three-dimensional representation of the plumbing system. Although a riser diagram is usually not drawn to scale, it should be correctly proportioned. In other words, a long run of piping in the plumbing plan should be shown as a long run of piping in the riser diagram. Conversely, short runs should be shown as short runs. Make sure, too, that you use proper symbols (from MIL-STD-17B) for the piping and fittings. This makes it easy for someone familiar with the symbols to read and interpret the drawing. A glance at figure 4-1 tells you, for example, that the plumbing system contains three gate valves and that all of the fittings are screw-type fittings. Be sure that the pipe sizes are properly labeled, especially where changes in pipe size occur. Label all fixture connections to identify to what fixture the piping connects. In figure 4-1, the fixtures are spelled out; however, it is also common practice to label the fixtures using an alphanumeric coding, keyed to a fixture schedule. Another type of riser diagram, though less often used in construction drawings, is the orthographic riser diagram that shows the plumbing system in elevation. When used, it is normally reserved for buildings that are two or more stories in height. Also, since you probably cannot clearly describe an entire plumbing system for a building in a single elevation, more than one orthographic riser diagram is necessary for the building. Examples of these diagrams can be found in Architectural Graphic Standards, by Ramsey and Sleeper.