Alphabet of Lines

Leaders

A leader is a line that has an arrow at one end and a text note or symbol at the other end. The arrow points to the feature or detail to which the note or symbol refers. Leaders are the same weight as dimension and extension lines.

Section Line

A sectional view reveals the interior construction details of a building component that has been sectioned. This view contains a cut component and provides a graphic representation of the building materials used in construction. Section lines are thin lines used in a sectional view to represent building material. Section lines are typically drawn at a 45 degree angle and provide a simple way to represent building materials.

Border Lines

Border lines are extra-heavy lines located near the edge of a sheet of drawing paper. They serve as the border for the drawing. They are also used to separate the various portions of the drawing, such as time block, notes, and revision block.

Break Lines

Break lines are used to indicate that only a portion of the object is being shown. There are two types of break lines: long break lines, and short break lines. Long break lines are used to show long, straight breaks. Short break lines are used to show short, irregular breaks.

Centerlines

Centerlines are thin lines used to indicate centers of objects such as columns, fixtures, equipment, and openings. Normally, these objects are located by dimensioning to the center. The centerline is also used to indicate a finished floor line. Center lines are composed of alternating long and short dashes.

Dimension Lines and Extension Lines

Dimension and Extension lines are thing lines that indicate the extent and direction of dimensions. Dimension lines extend the length of the distance being measure. A marking device, such as an arrow, dot, or tick mark, is placed at the end of the dimension line. Extension lines are drawn perpendicular to the dimension line to specify the features between which the dimension applies.

Hidden Lines

Hidden Lines are thin lines composed of short dashes. They define edges and surfaces that are behind other objects and are not visible in a particular view.

Object Lines

Object lines represent the main outline of the features of the object, building, walls, or walks. An object line is a heavy, continuous line, showing all edges and surfaces.

Property Line

Property lines are extra-heavy lines made up of long dashes alternating with two short dashes. The length a bearing(direction) of each line usually is identified on the site plan in a set of civil engineering projects.

Section Cutting Line

Section cutting lines are used to identify sectional views. A section cutting line marks the part of the drawing being "cut" to create a sectional view or detail. A section cutting line is also refereed to as a cutting plane line. Arrows on the ends of the line serve as directional indicators and indicate the direction from which the section is viewed.

Arrowheads

There are many types of arrowheads; each architect develops a unique style of indication. The purpose is to define the distance between the two points (extension lines) on the drawing. When space between extension lines is too small, the arrowheads are located on the outside with the dimension in the middle or off to the side and a leader line referring to the location for the dimension.