Architectural lines

 

Architectural lines 

 

Lines are the primary method of displaying images on architectural drawings. The lines must accurately and clearly represent the drawing content. There are a variety of line types found on drawings. Each type of line conveys a meaning in the way it is represented and its placement on the drawing. There are basically two widths of lines commonly found on architectural drawings, thick and thin. The purpose of different line widths is to make certain that lines stand out more than others. Thicker lines are meant to be more dominant than other lines. They may not be any more important, but they are the first lines that are intended to be seen by the viewer. For example, when you look at a floor plan, the wall lines and related features should be the main focus at first glance. Other lines, such as dimension lines, are equally important, but their appearance is subordinate to the lines used to create the plan. Even though national standards recommend two different line thicknesses for use on drawings, some companies use three line thicknesses to represent different lines on a drawing. Confirm the actual practice used by your school or company. This discussion introduces you to each of the lines commonly used in architectural draft-ing. Figure 6-1 shows each type of architectural line and its desired width.

Construction Lines and Guidelines

Construction lines are used for laying out a drawing. They are drawn very lightly so they do not reproduce and so they are not mistaken for any other lines on the drawing. Manually drawn construction lines are drawn with very little pressure using a pencil with 4H to 6H lead, and if drawn properly do not need to be erased. Use construction lines for all preliminary work. Construction lines are drawn on a separate layer when CADD is used. This layer can be turned on or off as needed. Guidelines are similar to construction lines in that they should be drawn lightly enough so they do not 

reproduce. Guidelines are drawn to guide your manual lettering. For example, if lettering on a drawing is 1/8" (3 mm) high, then the lightly drawn guidelines are placed 1/8" (3 mm) apart. Guidelines are not used with CADD. Some manual drafters prefer to use a light-blue lead rather than a graphite lead for all construction lines and guidelines. Light-blue lead does not reproduce in a diazo printer and is usually cleaner than graphite. Blue-line can reproduce in a photocopy machine unless it is drawn very lightly.

Object Lines 

In architectural drafting the outline lines—or object lines, as they are commonly called—are a specific thick-ness so they stand out from other lines, as they form the outline of views. Object lines are used to define the outline and characteristic features of architectural plan components, but the method of presentation can differ slightly from one office to another. The following tech-niques are alternatives for object line presentation:

● A popular technique is to enhance certain draw-ing features so they stand out clearly from outer 

items on the drawing. For example, the outline of floor plan walls and partitions, or beams in a cross 

section, can be drawn thicker than other lines so that they are more apparent than the other lines on 

the drawing. When drawn manually, these thicker lines can be drawn with a mechanical pencil or 

0.7-mm or 0.9-mm automatic pencil using a 2H, H, or F lead (see Figure 6-2A). This technique can 

also use light shading to highlight the walls of a floor plan. Dark shading can be used, but it hides 

the thicker outline lines.

● Another technique is for all lines of the drawing to be the same thickness. This method does not differentiate one type of line from another, except that construction lines are always very lightly drawn. 

The idea of this technique is to make all lines medium-thick to save drafting time. The drafter 

uses a lead that works best, although a mechanical pencil or 0.5-mm automatic pencil with 2H or H 

lead is popular (see Figure 6-2B). This technique can use dark shading to highlight features such as 

walls in floor plans, as shown in Figure 6-2C. The objective with any manual drafting line work is to 

get all lines dark and crisp. If the lines are fuzzy, they do not reproduce well.

● Some object lines may not be drawn as thick as others. This idea can be confusing at first. When 

you are creating an architectural drawing, you need to think about what features you want to be most 

visual. On a floor plan, for example, the outlines of the walls might be drawn thick to stand out clearly 

from other features. However, the outlines of cabi-nets, doors, and other objects might be drawn thin 

even though they are objects and their outlines might be considered object lines. The partial floor plan in Figure 6-1 shows this variation between object lines. Although this practice is common, the confusion can be compounded for the beginner because some variations can exist between offices. The best thing for you to do is spend as much time as you can look-ing at sets of architectural drawings with the goal of observing how lines are displayed. Also, quickly become familiar with the methods preferred by your instructor and the company where you work.

Dashed Lines

In mechanical drafting dashed lines are called hidden lines; the terms are interchangeable in architectural drafting. Dashed lines are used to show drawing features that are not visible in the view or plan. In architectural drafting, dashed lines can also be considered hidden lines because they are used to show drawing features that are not visible in the view or plan. These dashed features are important but subordinate to the main emphasis of the drawing. Dashed lines vary slightly from one office to the next. These lines are thin and generally drawn about 1/8" to 3/8" (3 to 10 mm) in length with a space of 1/16" to 1/8" (1.5 to 3 mm) between dashes. The dashes should be kept uniform in length on the drawing, for example, all 1/4" (6 mm) should have equal spaces. Dashed lines are thin, and the spacing between dashes should not be measured, but should be approximately the same. Draw dashed lines manually by estimating the dash length and spacing. It takes practice to manually draw dashed lines. Recommended leads for manual drafting are a 0.5-mm automatic pencil with 2H or H lead, or a sharp mechanical pencil with 4H, 2H, or H lead. Examples of dashed-line representations include beams shown in Figure 6-3, headers shown in Figure 6-4, and upper kitchen cabinets, dishwasher, and electrical circuit runs 

as shown in Figure 6-5. These concepts are discussed again throughout this textbook as used with specific applications.

Extension and Dimension Lines

Extension lines show the extent of a dimension. Dimension lines show the length of the dimension and 

terminate at the related extension lines with slashes, arrowheads, or dots. The dimension numeral in feet and inches, or millimeters, is generally placed above and near the center of the dimension line. Extension lines generally start a short distance, such as 1/16" (1.5 mm) away from the feature being dimensioned and typically run 1/8" (3 mm) beyond the last dimension line. When you are dimensioning to a feature such as the center of a window, the center line becomes an extension line. Figure 6-6 shows several extension and dimension lines. Further discussion and examples are provided in later chapters. Extension and dimension lines are generally thin, dark, crisp lines that can be drawn with a sharp mechanical pencil or 0.5-mm automatic pencil using 4H, 2H, or H lead, depending on the amount of pressure you use.

Break Lines

Break lines are used, for example, to remove a portion of an object, to show a partial view, or to shorten a long object. Break lines are also used to terminate features on a drawing when the extent of the fea-

ture has been clearly defined. Two types of break lines can be used in architectural drafting: the long 

break line and the short break line. The long break line is normally associated with architectural draft-

ing, and uses a break symbol that is generally drawn freehand. Figure 6-8A shows several examples. The short break line can be found on some architectural drawings. This line, as shown in Figure 6-8A, is an irregular line drawn freehand and is used for a short area. The short break line is less commonly used in architectural drafting than the long break line. Breaks in cylindrical objects such as steel bars and pipes are shown in Figure 6-8B.