Line Weights, Styles, and Types
The "weight" of a line simply refers to the thickness (or sometimes darkness) to which a line is rendered graphically. This basic graphic property has enormous effect upon how a drawing is perceived, and how the illusion of three-dimensional space is produced through two-dimensional drawings. Similarly, a range of line types (dashed, dotted, etc) may be deployed in different situations to produce a range of effects.
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Screenshot Albers Structural Constellation 1.jpg

A general discussion of line weight, style, and type in architectural graphic projection drawings is presented below. Some conventions discussed here differ for individual drawing types, as detailed on the following pages:

Line Weight

Line weight is the visual lightness or darkness and width of a line. Line weights add visual legibility and hierarchy to a set of drawings while maintaining clarity of representation. The quality of lines in an architectural drawing are particularly important as drawings are passed from architect to client or architect to contractor and must retain legibility to each viewer. A successful set of drawings has a consistent set of varied line weights, with a minimum of 3 or 4 contrasting weights, depending on the size and scale of the drawing.

Pencil lines should be solid and uniform in width across the entire length of the line. Keep constant pressure to the paper as you draw a line from start to finish. Though the pencil lead hardness will remain mostly unchanged, the lead width will need to be altered across different drawing scales. This is changed by sharpening or dulling the pencil and altering the pressure of the pencil onto the paper.

Line Weights (from lightest/thinnest to darkest/thickest)

Construction Lines (6H-4H, ~0.05mm - 0.1mm / 0.18 - 0.25 pt)
The initial lines of the drawing that help to lay out the drawing on the page and create the basic geometry and guides for the rest of the drawing. These lines are to be drawn very lightly - dark enough for you to see while drawing, but delicate enough to be easily erased later. Though these lines are typically erased for construction documents, they can be kept in presentation drawings to aid in representing an architectural concept and add visual interest.
Light Lines (4H-2H, ~0.10mm / 0.3 - 0.4 pt)
Action lines (such as door swings), information lines (such as dimension lines and section lines), overhead lines, and fill patterns are all drawn with light lines. Though these are light lines, it's important to remember that these are still intended to be visible - do not confuse "light" with "hard to see."
Medium Lines (F-H, ~0.2mm / 0.5 - 0.6 pt)
Secondary objects such as doors, furniture, cabinets, and other non structural architectural features are drawn in a medium weight.
Bold Lines (HB-B, ~0.3mm-0.4mm / 0.7 - 1 pt)
Outermost boundaries of objects, or those "silhouette lines" that border empty space or separate the figure of the depicted object from the ground, in orthographic views or in axonometric drawings.
Cut Lines (B+, 0.4mm and above / 1 pt and above)
Objects that are being cut through by the sectional plane, typically Walls, columns, and other structural and non-structural objects.

Breaking Convention

These drawings by Josef Albers demonstrate how illusions of impossible depth and surface can be suggested simply by breaking with the expected conventions of line weight.

Albers Structural Constellation 1.jpg

Line Styles

Solid Lines
Visible objects that can be seen in plan, section, elevation, or 3D views, as well as leader lines and dimension lines
Dashed Lines
Hidden objects or edges of objects below or above the sectional plane, or behind other objects.
Movement or Phantom Lines
Used to imply movement or direction, such as the alternate position of an object that can be moved. Most helpful to differentiate between moving objects and hidden objects within a drawing. Door swings, window swings, and sliding doors are examples of when to use movement lines.
Leader or Annotation Lines
Connect notes or references to objects or lines in a drawing. These are solid lines that end in an arrowhead, and may be straight, angled, or curved as necessary.
Break Lines
Used when the extents of a drawing cannot fit into the drawing frame, or when only a portion or partial view of a design is necessary. Also used to illustrate stairs that emerge out of the sectional plane of a drawing.
Center Lines
Indicate the center of a plan, object, circle, arc, or another symmetrical object.
Section Lines
Indicates the sectional plane for a cutaway view on a drawing, as well as the viewing direction of the associated view.
Dimension Lines
Used to show the measurement of an object in a single direction.

Line Types


Section / Cut Lines

These are typically the heaviest weighted lines, often drawn with an HB or B lead. There are also representational choices to consider regarding the base and poche of the section line. The section line can be a continuous line across the page or create a rectangular base underneath the building. Section lines can also be poché, where the cut spaces are filled in (either with black or gray).

Profile Lines

These lines represent the edges between an object or plane and open space and are the next in darkness. HB.

Elevation Lines

These are lines that define edges that are further away and can vary in weight, depending on how far away the object is. H or 2H.

Construction Lines

Lines that help you organize and construct your drawings and should disappear when you stand about 3 ft away from the drawing. 4H or 6H

Hidden Lines

Typically drawn as 'dashed' lines, these lines depict objects that are not visible in the drawing because they are above or beyond the section cut. H or 2H with consistent dashing. Not everything above or beyond may be represented – good examples include open spaces, canopies and overhangs.