General Information

Blueprint drawings—as applied to the building-construction industry—are generally used to show how a building, object, or system is to be constructed, implemented, modified, or repaired. One of the main functions of graphic symbols on construction drawings is to reference other drawings within the set. For example, a circle drawn around an area of a drawing with an extension to a number would indicate that this portion of the drawing has been drawn to a larger scale to provide more information than would be possible at the existing scale (Figure 8.1). In the preparation of working drawings for the building-construction industry, architects and engineers have devised systems of abbreviations, symbols, and keynotes to simplify the work of those preparing the drawings and to keep the size and bulk of the construction documents to an acceptable, comprehensible minimum. Drawing simple building components without the use of symbols would indeed be a tiresome task. Visualizing and reading construction drawings therefore necessitate a knowledge of symbols and abbreviations used in the construction industry and of their proper use in representing materials and other components and their locations (Figure 8.2). Symbols may vary slightly from one locale to another.

The majority of architects and engineers today use symbols adopted by the American Institute of Architects (AIA) and the American National Standards Institute (ANSI). However, designers and drafters continue to modify some of these symbols to suit their own particular needs for the types of projects they are normally commissioned to design. For this reason, most drawings have a symbol list or legend drawn and lettered either on each set of working drawings or in the written specifications. Modified symbols are normally selected by the consultant because they are easier to draw and interpret and are sufficient for most applications.

In order for this system of symbols to work, each drawing within the set has its own unique number. This is usually a combination of numbers: the number for the individual drawing as well as the page or sheet number on which the specific drawing appears. Individual drawings may be referenced many times throughout a set of construction drawings. The symbols discussed in this chapter are not all-inclusive by any means, but they are the ones that the builder or designer is likely to encounter in most general building-construction applications.

Figure 8.1 A computer-generated section of a residential structure showing different elements with encircled portions. These portions are detailed to a larger scale at another location within the set. Notice that the highlighted portions do not necessarily have to be circles but can take on other shapes.

Figure 8.1 A computer-generated section of a residential structure showing different elements with encircled portions. These portions are detailed to a larger scale at another location within the set. Notice that the highlighted portions do not necessarily have to be circles but can take on other shapes.

Graphic symbols are often used on building plans to show elements such as gas and water service lines and window types as well as to list drawing notes and identify finishes and revisions. The same graphic can be used for more than one purpose. For example, the same symbol is used for every revision; it is the number within the graphic that carries specific information. Trade-specific symbols are included for the electrical, HVAC, and plumbing trades.

One of the most important symbols to use right at the beginning of a new job is the directional symbol. This symbol, which is usually an arrow labeled "N" for north, enables the reader of a construction drawing to orient it. However, there are numerous variations of the "North" point symbol, depending on the designer's fancy (Figure 8.2). Whichever symbol is decided upon, a drawing is properly oriented when it is held so that the north arrow shown on the drawing is pointing toward north. The drawing must be properly oriented so the reader can relate the information on it to the surrounding area.

Figure 8.2 Examples of typical door and window symbols shown in both plan (as it may appear on a blueprint) and in pictorial form. Reading working drawings necessitates the ability to read, and understand and visualize the various symbols.

The following figures show some of the most common standard symbols; during the course of your work you will likely see many other types as well. For various reasons, some of the symbols on a drawing may not be standard. Many times you will figure out what a symbol means by analyzing it and thinking about what it looks like. The legend on a drawing should show any nonstandard symbols and their meanings. Occasionally a symbol for a particular component or device may have been specifically created by the architect or engineer who developed the drawing.

Figure 8.3 Different examples of north-point symbols. Architects and designers often like to design their own symbols for particular items.

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