38 Chapter 3
AutoCAD, these line-boldness conventions are replicated by configuring each line color as certain
line widths.- Border lines are roughly twice as bold as object lines, which in turn are roughly twice as bold as di-
mension lines. In addition, AutoCAD drafting uses colors to emulate each thickness (black or white
for objects, green for dimensions, blue for borders, etc.). In AutoCAD’s print-dialogue box you are
allowed to designate different line widths for each different color.
Line Types: The major line types and line thicknesses using pens or plotter machines are outlined
below. It becomes obvious from the table below that larger sheets require the use of thicker lines than
smaller sheets.
Object Lines.
Object lines, also known as visible lines, are solid lines used mainly to define the shape and size of a
structure or object. They are continuous prominent lines representing the edges of surfaces or the inter-
section of two surfaces, as shown in Figure 3.2. An object/visible line is typically drawn thick (dark) and
solid so that the outline or shape of the object (e.g., wall, floor, elevation, detail, or section) clearly stands
out on the drawing with a definite contrast between these lines and secondary lines on the drawing. They
are heavier than hidden lines, dimension lines, center lines, and broken lines. As we shall see later in
the chapter, blueprint drawings often contain different solid line types that are not object lines.
Dashed Lines.
Dashed or hidden lines serve more than one purpose in construction drawings. They are comprised of
medium- or light-weight, uniformly sized broken lines consisting of evenly spaced short dashes and are
generally intended to represent hidden surfaces or intersections of an object. On floor plans they may
be used to represent features that lie above the plane of the drawing, such as high wall cabinets in a
kitchen. You may vary the lengths of the dashes slightly in relation to the size of the drawing.
On remodeling-job drawings, they are also used to indicate the position of preexisting construction.
In some cases they are used for relationship clarification or to show alternative positions of a movable
component. To be complete, a drawing must include lines that represent all the edges and intersections
of the surfaces in the object. Many of these lines are invisible to the observer because they are covered
by other portions of the object. For example, in Figure 3.3A the dashed lines indicate the location of
blocking hidden behind the wall.
In architectural drafting dashed lines may be applied in different weights to reflect their purpose (e.g.,
to reflect importance or distance from the main view) while showing drawing features that are not visible
in relationship to the view or plan. These dashed features can be subordinated to the main emphasis of
the drawing. Hidden lines should typically begin and end with a dash, in contrast with the visible lines
from which they start, except when a dash would form a continuation of a visible line. Dashes should be
joined at comers; likewise, arcs should begin with dashes at tangent points. Hidden lines should be omit-
ted when not required for the clarity of the drawing. Although features located behind transparent mate-
rials may be visible, they should be treated preferably as concealed features and shown with hidden
lines. Examples of dashed-line representations include beams and headers, upper kitchen cabinets, un-
dercounter appliances (e.g., dishwasher or refrigerator), or electrical circuit runs, as shown in Figure
3.3B. Figure 3.3C is another example of hidden-line use.