Line weight is the visual lightness, darkness, or heaviness of a line within a drawing. In any architectural drawing, from a sketch to a construction drawing, the interplay of different relative line weights is used to communicate depth, importance, and proximity.  

THE WEIGHT OF YOUR LINES

Weight refers to the strength, heaviness, or darkness of a line against the background. It can be achieved through different thicknesses, intensities, and sometimes even different patterns – dashes, dots etc. Traditionally, you would generate a heavier line by applying more pressure, or by angling the pencil to produce a thicker line. Today, you can find pens with different nib sizes, and pencils and leads with different hardnesses to aid the process of producing different line weights.  

Additionally, all architectural computer-aided design programmes have in-built systems for generating and managing line weights in architectural drawings. These systems range from the simple (closest lines are darkest, further away are lighter) to the highly complex (elements in the drawing have pre-determined line-weights, based on value-decisions make by the architect).

Before jumping in to these more intensive situations, it is important to have a grasp on what line weights mean and how they are read, and what you should consider when incorporating them into your own work.  

HOW DO ARCHITECTS USE LINE WEIGHTS?

There are a number of different situations in which architects use line weight. Line weight is a notational device, and can be used to identify different types of information which are layered in the same drawing. It is used in all drawing types – sketches, sections and elevations, plans, diagrams, perspectives, and details.