Architectural Line Weights and Line Types

Understanding architectural line weights and line types is a key part of the early architectural student journey. In architectural drawings, line weights and line types are essential because they help convey the importance and hierarchy of different elements within the design. A well-executed architectural drawing should be clear and easy to read, and line weights play a significant role in achieving this goal.

Let’s start by clarifying what the difference is between a line weight and a line type. 

Line Weight – a line weight is the thickness of the line

Line Type – a line type is the style of the line. This could be a continuous solid line, a dashed line, or a line that contains symbols, amongst others.

Throughout this blog post, we will explore the importance of line weights and line types in architectural drawings.

Architects Drawing boards

Line Weights in Architectural Drawings

Here are a few reasons why line weights are important in architectural drawings:


Differentiating Between Elements

Line weights are used to differentiate between different elements of a building or structure, such as walls, windows, and doors. By assigning different line weights to each element, the drawing becomes more organised and easier to understand. For example, thicker lines may be used to depict the outline of the building, while thinner lines may be used to represent interior walls.


Conveying Depth

Line weights can also be used to convey depth in architectural drawings. By using a heavier line weight for elements in the foreground and a lighter line weight for elements in the background, the drawing can create the illusion of depth and dimension.


Communicating Information

Architectural drawings often contain a lot of information, including measurements, materials, and construction details. By using line weights to emphasise important details, such as structural elements or notes, the drawing becomes easier to read and understand. This is especially important when the drawing is being used by contractors, builders, or other professionals who need to understand the design in detail.


Enhancing Aesthetics

Finally, line weights can enhance the aesthetics of an architectural drawing by creating a sense of balance and harmony. By using a variety of line weights, the drawing can become more visually interesting and appealing to the eye. In addition, careful use of line weights can help draw attention to important elements of the design and create a sense of movement or flow within the drawing.


Choosing your Line Weight

Line weights play an essential role in architectural drawings by helping convey the hierarchy, importance, and various components of the design. Different line weights are used to represent different elements, and understanding when and how to use them is crucial for creating clear and informative architectural drawings.

Traditionally, when architects drew their plans with pen and paper, there was a limited amount of line thicknesses available. Usually, every architect would own a Rotring Architectural Drawing Set. The set contained a set of technical drawing pens that all had a different thickness ranging from 0.10mm to 2.0mm. 

The most common lineweights was usually:

  • 0.7mm – Thickest
  • 0.5mm – Thick
  • 0.35mm – Thin
  • 0.25mm – Thinner
  • 0.18mm – Thinnest

Sometimes you will see examples where a thicker felt tip pen has been used for outlining or ground lines etc. This often comes down to personal preference and style.

Architectural line weight examples

Here’s a breakdown of common line weights and their uses:


Outline (Thick Line Weight)

The outline or heavy line weight (typically 0.50mm or thicker) is used for the most prominent elements of a drawing. It’s commonly employed for the building’s exterior walls, structural columns, and important architectural features. The thick outline provides a clear boundary for the building, making it stand out.


Cut Line (Medium Line Weight)

The cut line, also known as the medium line weight (usually around 0.35mm to 0.50mm), is used to represent elements that are cut through in a section view. This includes walls, floors, and structural elements that are essential for understanding the building’s interior layout.


Hidden Line (Dashed Line)

Hidden lines are represented using dashed lines. These lines (commonly 0.18mm to 0.35mm) indicate features that are not visible in the current view but exist in the design. Examples include structural elements obscured by walls, plumbing behind fixtures, and electrical conduits within walls.


Centerline (Thin Line Weight)

Centerlines are used to denote the centre or axis of symmetrical features. These lines (typically 0.13mm to 0.18mm) help in aligning and dimensioning objects accurately. Examples include centerlines for doors, windows, and circular elements.


Dimension Lines (Thin Line Weight)

Dimension lines are usually thin (around 0.13mm) with arrows at each end. They are used to indicate measurements and sizes of objects or spaces within the drawing. The dimension lines are accompanied by dimension numbers specifying lengths, widths, and heights.


Leader Lines (Thin Line Weight)

Leader lines are thin lines (around 0.13mm) with arrows or dots and are used to point to specific notes, labels, or annotations on the drawing. They help in associating text with specific elements or features in the design.


Text and Annotations (Thin Line Weight)

Text, labels, and annotations are typically drawn using thin line weights (around 0.13mm) to ensure they don’t overpower the drawing. These elements provide essential information such as labels for rooms, materials, and notes.


Hatch Patterns (Thin Line Weight)

Hatch patterns are used to represent materials and textures within the drawing, such as bricks, tiles, or insulation. These patterns are typically thin (around 0.13mm) to avoid overwhelming the drawing but should still be distinct enough for identification.


By using various line weights strategically, architects and drafters can create architectural drawings that are not only aesthetically pleasing but also convey precise information about the design. This helps communicate the design intent clearly to contractors, builders, and other stakeholders, ensuring that the construction process goes smoothly and as planned.

Architectural drawing

Line Types in Architectural Drawings

In addition to line weights, architectural drawings also make extensive use of specific line types to convey different types of information. These line types serve to represent various building components and materials, as well as to communicate specific instructions to architects, engineers, and builders.

Here are some common architectural line types you’ll see when you study architectural drawings:


Continuous Lines

These are the most basic and commonly used lines in architectural drawings. They represent visible edges and outlines of objects, such as walls, doors, windows, and structural elements. Solid lines are typically drawn with a standard line weight to make them easily distinguishable.


Dashed Lines (Hidden Lines)

Hidden lines are used to indicate features that are not visible in a particular view but exist in the building design. For example, they might represent interior structural elements hidden behind walls or objects located above or below the current view plane.



Centerlines are dashed lines used to indicate the centre or axis of symmetrical features, like doors, windows, or circular elements. They help in aligning and dimensioning objects accurately.


Phantom Lines

Phantom lines (Dashed and Dot-Dashed Lines) are often used to represent alternate or optional positions or features. They may indicate possible future additions, temporary elements, or features that are not part of the current design but may be included later.


Break Lines

Break Lines (Zigzag Lines) are used to indicate that a portion of an object has been intentionally omitted from the drawing for the sake of clarity or to fit the drawing on a sheet of paper. They are especially useful when drawing long objects, like pipes, beams, or walls.


Dimension Lines

Dimension Lines (Thin Lines with Arrows) are used to indicate the distance or size of objects and features within the drawing. They include arrowheads at either end and are accompanied by dimension numbers that specify the length or size being measured.


Leader Lines

Leader Lines (Thin Lines with Arrows or Dots) are used to point to specific notes, labels, or annotations on the drawing. They help clarify which text corresponds to which part of the design.


Cutting Plane Lines

Cutting Plane Lines (Alternating Long and Short Dashes) are used to define the location and direction of a section cut through a building or object. They help illustrate what the cross-section of a structure would look like.


Grids and Boundary Lines

Grid and Boundary Lines (Dashed lines with Short Dashes or Dots) are used to indicate site boundaries and structural grid lines. Different dash arrangements are chosen for different requirements, and sometimes displayed in different colours for easier understanding of the drawing.


Architectural Line type examples
Understanding these architectural line types is crucial for accurately interpreting and creating architectural drawings. When combined with appropriate line weights and colours, these line types contribute to the clarity, readability, and precision of architectural documentation.


In summary, line weights and line types are essential tools in architectural drawings. They serve practical purposes by conveying information effectively and organising the visual hierarchy of a design. Understanding how to use them appropriately is crucial for clear and professional documentation.

Additionally, you have the flexibility to develop your own unique style by adjusting line weights thoughtfully. Whether you prefer a crisp and precise look or a more expressive touch, the choice of line weights can make your drawings distinctive and reflective of your personal design approach.

As part of your learning process, it’s also beneficial to explore architectural precedents. Architectural websites and resources offer a wealth of drawings by different professionals. Analysing how various architects use line weights and line types can provide valuable insights into different styles and communication techniques.

In conclusion, line weights and line types are practical tools that serve a crucial role in architectural drawings. They facilitate effective communication, enhance aesthetics, and provide architects with the means to express their unique design visions clearly. 


We hope this post helps you understand line weights and line types as you start your architectural drawing journey. All the best!

Thank you for reading! 🙂



Written by Emma Walshaw, Architectural Technologist and founder of First In Architecture and Detail Library. Emma has written a number of books about construction and architectural detailing.

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  1. Really good articles once again.
    I was taught line weights as an apprentice using Rotring pens, Cad is an amazing tool.

    Keep up the good work

    • Thank you Mel.

  2. You are only getting better!

    • Thank you Edward 🙂

  3. Thank you

    • I have a question to ask

      • Hello Sadiq, how can we help?

  4. I have really enjoyed and gained a lot, thanks Emma.

    • Thank you Kakaire 🙂


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