Poche’ Technique in Architectural Drawings

Design & Drawing by Casey Revelle and Robert Konzelmann

In architecture, poche’ is the process of darkening the area of walls, columns, and other solid elements created by a cut plane . This process is frequently utilized in representing buildings and objects in plan, section, and figure-ground (drawings that create a high contrast between spatial areas and cut elements). Blackening the cut elements helps viewers easily identify the depth of elements in floor plans and sectional drawings.

Drawings represented in a smaller scale benefit from the high contrast nature of poche’; it is an ideal method for effective communication when drawings are intended to be displayed in a presentation-like format, or the audience is standing more than 3 feet (1 meter) away from the drawings. In contrast, if a drawing is depicted in a large-scale format, the poche’ method has the potential to dominate and wash out the main content of the drawing.

The main question then becomes what are the appropriate scales that the poche method can be used to enhance the outcome of plan and section drawings?

I frequently use poche’ when I need to display drawings in the initial phases of design that do not contain many details, but rather display the functional configurations in plans and spatial articulation in section drawings. Any drawings that utilize scales smaller than 1/4’=1’-0” or 1:50 benefit from this presentation method. Periodically, using a middle-gray value instead of black is appropriate for drawings depicted at a scale close to 1/4’=1’-0” to reduce the high contrast between cut elements and spatial void in plans and section drawings. By doing so, the elements represented do not visually dominate a composition and are less straining on the eye of the viewer.

Drawings that are depicted in a scale larger than 1/4’=1’-0” should use a hierarchy of line widths and weights to create depth of elements in the drawings.

The figure above illustrates how the poche technique defines the cut plane in the building section. The filled walls, floor plates, ceilings, and solid elements define the spatial aspects of the building and allow viewers to observe how the various building elements are unified, as well as establish a platform for other analytical studies to be incorporated such as solar studies as seen in the figure mentioned above.

LINE TYPES

Kidosaki House designed by Tadao Ando / Section drawing by Otto, A. Chanyakorn

Line type is one of the drawing elements that should be learned.  Each line type serves a purpose in drawing, and they also convey their own meaning in architectural drawings. Thus, in order to fully convey our communication in drawings, we should understand its functions.  I normally employ four line types in my drawings, and I personally enjoy the simplicity of utilizing only these four line types. Whether drawn on a computer or by hand, these line types help to convey  meanings in architectural graphic . Drawings are easier to read and interpret when line types are properly applied. The line types below are commonly used in my work:

Continuous lines use for cut and visible edges of objects. They allow depict the form of objects. Continuous lines also use for dimensional purposes. The use of line width for continues line is varies (Please see line width article for more detail).

Dashed lines represent concealed edges of objects, or elements that being removed for our view. I normally use dashed line with thin line width. Dashed lines also commonly use with thin line width.

Dot-dashed lines use for gird section line, building axes, centerlines.

Dotted lines indicate the edges of object lie above the cut plane in floor plan drawing or section plane. Since the dotted lines are difficult to see when we depict them with thin line width, I normally use medium line width for dotted-lines. I found it was difficult to use dotted lines when drawn by hand. Thus, I replace them with dashed lines instead.

Line Weights No.2: Implementation

I have written about line weights in the previous post of this blog. I would like to talk more about line weights in term of their implementation to drawings. Some may have a question about what the difference between line weights and line widths. They essentially are the same meaning but people use them differently. Most common use is the term “line weight”. In the history of making a drawing, we actually press the weight to a pencil to control the weight of a line. In the modern era, much of drawings are being produced via computational tools then drawings are being printed via printers. A printer controls the thickness of lines by using a width of lines to differentiate a thickness of lines. Therefore, the proper term for all lines that being produced via a printer should be called line widths.

Line widths play a significant role in architectural drawing. Without line width controls, we may not be able to effectively communicate the depth of drawings as we intended to. The examples above will offer you an idea and the outcome of drawings that is drawn with or without utilizing line widths as a method of conveying depth in building floor plans.

The image no. 1 is using a single line width.  Using a single line width makes the drawing difficult for a viewer to read the drawing and differentiate between solid matters and spatial voids in a drawing particularly when a drawing is a complex one. Therefore, using a single line width in drawings for communication purposes is not recommended.

The image no. 2 is using a hierarchy of line width to differentiate between solid matters and spatial voids. It is a commonly use in architectural drawings. The method helps facilitate the readability of a drawing very well when the line widths are implemented effectively. There are three line widths were used in this drawing: think (.35 mm or 1 pt), medium (.18 mm or 0.5 pt) and thin (.09 mm or .25 pt). I personally often use this method of convey the depth of my drawings because it is simple. However, this method may not work as we expected it if a drawing is created in a small scale (1/16″=1′-0″ closed to 1:200 in metric or smaller), particularly, when a viewer has to view this from a far distant.  Consequently, the method of conveying drawing depth in the drawing no. 3 is more appropriate for presentation of small scale drawing perhaps.

The drawing no. 3 is utilizing a technique called “poche”. It is a process of darkening the cut area of the solid elements such as walls, columns, etc. It is commonly used in building floor plan drawings and building section drawings..  Since the technique offers a strong contrast between spatial voids and solid element in building floor plan drawings, it is a lot easier for a viewer to quickly conceive the depths in the drawing. The poche technique in drawings is an ideal method of representation in drawings that are created with small scales, and being seen from a far distant likes presentation for a client in a meeting room with a group of people or pin-up situation in school project review.

LINE WEIGHTS : NO.1

One on the most fundamental part of drawings that help will strengthen the quality of each drawing is line weights (Some people prefer to use line widths).  Line weights convey depth and indicate various functions of each line in drawings. It is also portrays the appealing of drawings if line weights are assigned to drawings properly. I have been trying to explore the effective method of utilizing the line widths in architectural drawing (AD). I recently have come to the final conclusion of categorizing  line widths for both computational and manual methods of drawings in to three sizes.

-Thick line depicts cut edges of solid components:

Setting for computational method: 0.35 mm in metric, 0.014 in. in U.S measuring system. 1 pt. in graphic application

-Medium line uses for cut glass plane.

Setting: 0.18 mm., 0.007 in. and 0.5 pt.

-Thin line depicts visible, concealed, and projected edges

Setting: 0.09 mm., 0.003 in. and 0.25 pt.

DRAWING METHOD

Drawing is one of the essential elements in architectural design process. Either producing drawings by hand or computational methods, the essence of effective communication of design ideas in architectural design remains the same. It is a same principle with writing. The rules of syntax, spelling, grammar still apply to whether writing by hand on a piece of paper or using keyboard.  In architecture design, we utilize drawings as a vehicle of our thoughts, a communication of our ideas, and articulating our spatial imaginations.