Technical Drawing And Drafting Techniques

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Pragmatically, architectural drawings are essentially one of two types. The first type is a technical format, e.g. working drawings (also called construction or production drawings). The second type of drawing is graphic and artistic in nature and tends to be more creative, such as design, presentations or concept drawings.Working drawings will typically contain much more data and information than graphic drawings (Figure 4.6). Such information would likely include dimensions, material and finishes data, interior and exterior details, as well as structural, mechanical, electrical, plumbing and other information—in fact, everything a contractor would need to build the project.

Design and presentation drawings serve a totally different purpose or function, generally to sell the scheme, and are typically produced during the initial developmental stages of a project (for client approval) or for competitions. These may include color, shadow, and anything that would enhance the project's appeal to the client (or jury). Design drawings are also likely to include perspective sketches or renderings of the project where this adds to the projects understanding or appeal. Figure 4.7 shows a presentation drawing of a week-end villa for a Middle Eastern client by Ibtesam Sharbaji.The ink drawing includes suggested furniture layout and other pertinent information to sell the scheme to the client.

Paul Laseau in his book, Architectural Representation Handbook, rightly points out that conventions play an essential role in the realm of architectural representation within the context of common perceptions and understanding. They basically reflect a common language that permits us to mentally organize what is being communicated. Laseau says,"Conventions have evolved from historically practical needs within the design process, such as the ability to establish scale, proportion, dimension; the need to identify parts, or portray the views one might see when moving through an environment; and the need to evaluate a building design qualitatively and quantitatively. The terms elevation, section, plan, and perspective each have a commonly understood meaning and represent a shared expectation among designers and the people with whom they work."There are three basic types of convention: 1. Orthographic projection, 2. Paraline projection, and 3. Perspective projection.

Orthographic Drawing and Projection (Two-Dimensional Drafting)

Common types of orthographic drawings include plans, elevations and sections. The most obvious attribute of orthographic drawings is its constant scale, that is, all parts of the drawing are represented without foreshortening or distortion, retaining their true size, shape, and proportion. Thus, a four foot square window will always be drawn to be four feet, no matter how far it is from our viewpoint (Figure 4.8).

Plans are orthographic views of an object as seen directly from above. Floor plans are the most common form of plans and depict the layout of a building. A floor plan is represented by a horizontal section taken through the building or portion of a building just above the win-dowsill level. In addition to the arrangement of rooms and spaces, floor plans should show the location of various architectural elements such as stairs, doors, and windows, and also details like wall and partition thickness. The greater the scale of a drawing, the more detail that is to be included in it (Figure 4.9). Thus, a drawing of '/4 inch = 1 foot scale will typically contain more information and show greater detail than a drawing of '/o inch = 1 foot scale. Other types of plans include site plans which typically show the layout of a site, and reflected ceiling plans which are normally used to locate light fixtures and a ceiling's design features.

Reflected ceiling plans are actually another variation of a section, representing an orthographic view of the ceiling of a room or space. Normally, the reflected ceiling plan is identical to the floor plan, and theoretically shows construction elements that touch the plane of the

Detail Drawing Mall
FIGURE 4.6 Part of a first floor plan for a shopping mall, showing some of the information a general contractor or builder would need to have on construction documents in order to build the project.
Sketching Portable Residences
FIGURE 4.7 Example of a design drawing (as opposed to a working drawing) of a ground floor plan for a residence by Ibtesam Sharbaji.

ceiling, as well as the ceiling itself and fittings in the ceiling. Designers often take liberties and sometimes show elements that do not touch the ceiling (e.g. doors and cabinets) to make it easier for the contractor to follow the plans. Elevations are vertical views of the exterior of a building or its interior. Interior elevations consist basically of a vertical front view of walls, partitions, etc. without the use of perspective (Figure 4.10). Elevations are necessary because plans can only show the dimensions of length and width, and not height. Elevations can also communicate essential information like type of materials and finishes and their extent.

Sections are also orthographic views of an object, and supplement the information on plans and elevations. As the term implies, a section depicts a vertical cut through a structure

Home Drawing For Engineering

FIGURE 4.8 An example of orthographic projection depicting the roof (top view), and two elevations. In orthographic projection, all elements are shown in their true relationship with each other. (From Ballast, David K, Interior Design Reference Manual, Professional Publications, Inc., Belmont, California)

FIGURE 4.8 An example of orthographic projection depicting the roof (top view), and two elevations. In orthographic projection, all elements are shown in their true relationship with each other. (From Ballast, David K, Interior Design Reference Manual, Professional Publications, Inc., Belmont, California)

Orthographic Roof Plan Detail

FIGURE 4.9 Drawings drawn in different scales: A. 1/500 scale; B. VS inch = 1 foot ; C. 14 inch = 1 foot and D. 114 inches = 1 foot. Notice that the 1/500 scale drawing is basically a block plan and incorporates very little detail, and thus cannot be built from, unlike the 114 inch = 1 foot drawing which gives the information necessary for its purpose.

or portion thereof, offering clarification to aspects of a design, in addition to essential information which plans and elevations alone cannot furnish, such as heights of doors, windows and ceilings, or floor and foundation construction details, location and depth of recesses, etc. (Figure 4.11). In addition to the above, designers often need to furnish other types of drawings with adequate details and specifications so that the contractor can build the project as originally conceived.

Elevation Drawn Scale
FIGURE 4.10 An example of an exterior elevation of a hotel originally drawn to '/s inch = 1 foot scale, and an interior design elevation of a wall, originally drawn to 'k inch = 1 foot scale.

Paraline (Pictorial) Drawings and Projections

Paraline drawings are used to communicate a sensation of three-dimensional space in a single image. However, they differ from perspective drawings in one important aspect, mainly: all parallel lines in reality remain parallel in paraline drawings, whereas in perspectives they converge to a vanishing point.

Designers regard paraline drawings as a form of shorthand for the creating a credible three-dimensional image of a space, and because of their ease of construction, they have enjoyed considerable popularity amongst designers for presentations. Designers are also attracted to paraline drawings because of their constant scale, which makes them especially useful in taking advantage of today's technological revolution including the rapid duplication capabilities of modern computer graphics. Paraline drawings are also used extensively in catalogs, in general sales literature as well as in technical work.

There are several classifications of paraline drawings and projections, each named after the method of projection that is used to make them. The most important ones for space planners and designers include three basic types: axonometric, plan oblique, and elevation oblique.

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FIGURE 4.11 An example of a typical design section through a building. (Courtesy Department of Computer Science and Engineering, University of Washington)

Axonometric Drawings

An axonometric drawing is one that is accurately scaled and depicts an object that has been rotated on its axes and is inclined from a regular parallel position to give it a three-dimensional appearance (Figure 4.12). The principal advantage of axonometric is that one can use an existing orthographic plan to start a drawing without any redrawing. The plan is simply tilted to the desired angle. In much of Europe, an axonometric drawing means that the axis is at a 45 degree angle, and for an isometric drawing, the axis is 30 degrees/30 degrees or 30 degrees/ 60 degrees.

Axonometric drawings can take on one of several forms, the most common being isometric, diametric, and trimetric. Figure 4.13 illustrates the different types of paraline drawings.

Isometric Drawings

Isometric drawing render a three-dimensional view of an object in which the two sets of horizontal lines of the object are drawn at equal angle and all vertical lines are drawn vertically. The resulting drawing has all three angles equally divided about a center point, and all three visible surfaces have equal emphasis. Orthographic drawings cannot be used in isometric drawings.

One can use any angle to draw an isometric, but the most common one is 30 degrees because it is a standard triangle and gives a reasonably realistic view of an object. Isometrics are easy and quick to draw and can be measured at any convenient scale

Dimetric

A dimetric projection is an axonometric projection of an object placed in such a way that two of its axes make equal angles with the plane of projection, and the third axis makes either a smaller or a greater angle.

Trimetric

A trimetric projection is an axonometric projection of an object so placed that no two axes make equal angles with the plane of projection, so that each of the three principal axes and the lines parallel to them, respectively, have different ratios of foreshortening (and therefore drawn at different scales) when projected to the plane of projection. The wide angle choice gives the designer considerable flexibility and control of the pictorial view.

Plan Oblique (Plan Projection)

Ching states that "a plan oblique orients a horizontal plane or plan view parallel to the picture plane and therefore reveals its true shape and size." A 45 degree/45 degree oblique has a

Architectural Representation
FIGURE 4.12 An example of an axonometric drawing by Brian Healy. (From Laseau, Paul, Architectural Representation Handbook, McGraw-Hill, New York)

higher angle of view than an isometric, giving more emphasis to horizontal planes. A 30 degree/60 degree oblique also has a high angle of view with one vertical plane receiving more emphasis than the other. Plan obliques are constructed by projecting vertical elements up from an orthographic plan.This facilitates showing the true form of horizontal planes as well as in depicting horizontal circular planes. In plan oblique, all vertical and parallel lines remain parallel and can be drawn to scale (Figure 4.14).

Elevation Drawing Ching Design Drawings
FIGURE 4.13 Diagram depicting the various pictorial and projection systems used by designers. (From Ching, Francis D.K., with Juroszek, Steven P, Design Drawing, Van Nostrand Reinhold, New York, 1998)
Facade Elevation Oblique Projection
FIGURE 4.14 An example of a plan projection drawing by Richard Meier of Shamberg House. Plan projection is the most commonly used form of paraline drawing. (From Laseau, Paul, Architectural Representation Handbook, McGraw-Hill, New York)

Elevation Oblique

Elevation oblique rotates the principal vertical face to be parallel to the picture plane to reveal its true shape and size, which in turn allows us to directly construct an elevation oblique from an elevation view of the principal face. This face is usually the longest, most important façade of the object. Oblique drawings reflect the true shape of planes parallel to the picture plane, and rather than fixing the viewer in one position, this drawing allows the viewer the choice of many observation points.

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Responses

  • rodrigo
    What are the tecnical drwaings in interior desing?
    2 years ago
  • Sebhat Kinfe
    When would a paraline image be shown to a client?
    11 months ago
  • topias
    Is plan elevation and section are orthographic projection?
    2 months ago
  • wilcome roper
    How to draw angle walls from rotated plan pull down perspective method?
    19 days ago

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