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Form refers to the shape or configuration of a building. Form and its opposite, space, constitute primary elements of architecture. The reciprocal relationship is essential, given the intention of architecture to provide internal sheltered space for human occupation. Both form and space are given shape and scale in the design process. In addition, the placement of a building form in relation to its immediate site and neighboring buildings is another crucial aspect of this form/space relationship. Just as internal space is created by voids in building form, exterior space can be defined or poorly defined by the building form as well.
For instance, consider the difference between an infill building that fits tightly within its' site boundaries (leaving no unoccupied space on the site, except perhaps a defined outdoor courtyard) and a freestanding building located within a large expanse of parking. Without the aid of other space-defining forms such as trees, fences, level changes, and so forth, it is very difficult for a large space to be defined or satisfactorily articulated by most singular forms.
A number of aspects must be considered in order to analyze or design an architectural form, including shape, mass / size, scale, proportion, rhythm, articulation, texture, color, and light.
Shape refers to the configuration of surfaces and edges of a two- or three-dimensional object. We perceive shape by contour or silhouette, rather than by detail. See Fig. 1.
Primary shapes, the circle, triangle, and square, are used to generate volumes known as "platonic solids." A circle generates the sphere and cylinder, the triangle produces the cone and pyramid, and the square forms the cube. Combinations of these platonic solids establish the basis for most architectural shapes and forms. See Figs. 2 and 3. Recent advances in digital technology have promoted the design and representation of more complex, non-platonic forms.
Volumetric shapes contain both solids and voids, or exteriors and interiors. Some shapes are formed through an additive process, while other shapes are conceptually subtracted from other solids. See Fig. 4.
Shape preferences may be culturally based or rooted in personal memory, or convention. For example, a dome or steeple may connote religious architecture in some cultures, while an American child's drawing of a house often depicts a square shape with pitched roof—a shape that many houses do not possess in our culture.
Mass combines with shape to define form. Mass refers to the size or physical bulk of a building, and can be understood as the actual size, or size relative to context. This is where scale comes into play in our perception of mass. See Fig. 5.
Scale is not the same as size, but refers to relative size as perceived by the viewer. "Whenever the word scale is being used, something is being compared with something else." (Moore: 17) This relation is typically established between either familiar building elements (doors, stairs, handrails) or the human figure. Scale may be manipulated by the architect to make a building appear smaller or larger than its actual size. Multiple scales may exist within a single building façade, in order to achieve a higher level of visual complexity. See Figs. 6 and 7.
The term "human scale" is frequently used to describe building dimensions based on the size of the human body. Human scale is sometimes referred to as "anthropomorphic scale." Human scale may vary by culture and occupant age. For example, buildings occupied primarily by children, such as schools and child development centers, should be scaled in relation to the actual size of children. The roadside service station depicted in Fig. 8 combines human and vehicular scales in a single façade.
In general, proportion in architecture refers to the relationship of one part to the other parts, and to the whole building. Numerous architectural proportioning systems have developed over time and in diverse cultures, but just a few specific examples are listed below.
Since Antiquity, architects have devised proportioning systems to visually unify all the parts of a building through the same set of proportions. This process creates an internal coherence and sense of order apparent in the building, even if the underlying proportioning system is not known to the observer. These systems can be arithmetic, geometric, or harmonic.
Arithmetic: The Ancient Greeks used clear mathematical ratios for both visible and auditory phenomena, such as architecture and music. For instance, Pythagoras emphasized the importance of numbers. Originating in Antiquity, the "Golden Section" has been used by Renaissance theorists, modern and contemporary architects. The Golden Section or Golden Mean is both arithmetic and geometrical, and is prevalent in both the natural world and classical architectural design. It may be expressed as a:b = b (a+b). This relationship can be verbally described as: a is to b, as b is to the whole. The Golden Section is also apparent in the Fibonacci series of integers: 1,1,2,3,5,8,13,21,34,55, etc. Each succeeding number is the sum of two previous numbers. This series forms the basis for a spiral, as found in the snail's shell or the spiral volutes of ionic column capitals.
Geometric: In Classical architecture, the diameter of a classical column provided a unit of measurement that established all the dimensions of the building, from overall dimensions to fine detail. This system works for any size of building, since the column unit fluctuates while the internal relationships remain constant. Drawings of the "classical orders" explain this set of relationships geometrically.
Harmonic: The ancient discovery of harmonic proportion in music was translated to architectural proportion. For instance, this system posits that when the ratio of 1:2, 2:3, or 3:4 is applied to buildings or rooms, harmonious proportion results. The early Renaissance architect Alberti credited the harmony of Roman architecture and the universe to this system. The Renaissance architect Palladio, along with Venetian musical theorists, developed a more complex system of harmonic proportion based on the major and minor third—resulting in the ratio of 5:6 or 4:5.
Material and Manufactured Proportions
Most contemporary buildings are proportioned according to the industry standard unit size of the primary mass-produced building materials employed. Based on the inherent properties of each material, conventional sizes and proportions have resulted. For instance, bricks, concrete masonry units, light wood members, plywood, and gypsum wallboard are always fabricated and sold in conventional sizes. The dimensions of these elements form another unit of measurement within the building.
The structural capacity of a particular material results in distinct proportions. The maximum span and depth of a stone lintel is very different than a steel lintel because of different structural properties. See Fig. 12.
The reoccurrence or repetition of architectural elements, shapes, structural bays, windows, etc. establishes a rhythm, which may be regular or complex. A static building possesses a rhythm, while the movement of inhabitants through a building may also establish a pattern or rhythm of human movement. See Fig. 13 for an example of how adjacent individual building rhythms also create a larger street wall rhythm.
How building surfaces come together to define form is often described as "articulation." The treatment of edges, corners, surface articulation of windows (horizontal, vertical, static field), and the visual weight of a building all contribute to the articulation of the form. See Fig. 14.
G. Texture and Color
Both texture and color are inherently linked to materials, and can be used to alter the perception of any given form. Consider how the shift from a light to dark paint color can radically reduce the apparent size of a room, or how a smooth stucco or rough brick finish can alter the size and visual weight of a house. As illustrated in Fig. 15, the same stone rendered smooth, rusticated, or intricately carved, results in different textures and colors.
Form is perceived differently depending on the light conditions within which the building is viewed. The prominent modern architect Le Corbusier emphasized the important relationship between light and form in his famous statement, "Architecture is the masterly, correct, and magnificent play of masses brought together in light. Our eyes are made to see forms in light; light and shade reveal these forms." (Le Corbusier: 29) See Fig. 16 for an example of the significant role of shadow in our perception of a building.
The following case study examines why a particular built form was used and how it enhances the aesthetics of that particular building. By comparing two buildings of similar programmatic use, in this case recent museum projects, we may see how the chosen forms were employed. The first example is the Metropolis Museum in Amsterdam designed by Renzo Piano Workshop. The simple building shape is reinforced by the large literal size, gigantic scale, and homogenous, light-absorptive copper cladding of the building exterior. Complex form and surface articulation is intentionally avoided in order to heighten the singular form. Because the museum is built above a highway harbor tunnel portal within an industrial harbor landscape, this form is quite appropriate to the scale and materiality of the surrounding architectural context. See Fig. 17.
The second example is the Guggenheim Museum in Bilbao, Spain designed by Frank Gehry Architects. Although also large in literal size, this design employs a complex, non-rectilinear shape that uses form and surface articulation to reduce the building scale. The choice of light reflective titanium exterior cladding further dematerializes the building form and uses light and shadow to continuously modulate the exterior surface. See Fig. 18.
In both cases, a careful combination of a number of architectural qualities—shape, size, scale, articulation, texture, and color—work together to produce the desired form.
Relevant Codes and Standards
In some jurisdictions, architectural form is controlled or limited by both zoning and building codes. For example, a "Floor Area Ratio" (FAR) is often used to control the mass or building square footage allowable on a site of a particular size. For example, a 100' x 200' building lot of 20,000 square feet, with an FAR of 3, would allow a maximum building area of 60,000 square feet. If the building footprint completely filled the site, the maximum building height would be three stories, while a building that only occupied one half the site (10,000 square feet) would be built to six stories. In combination with building height limitations and "setback" or "build to" lines, the allowable mass and shape of a building is often tightly controlled.
- Architecture: Form, Space, and Order, 4th Edition by Francis D.K. Ching. New York: John Wiley & Sons, Inc., 2007.
- Dimensions: Space, Shape & Scale in Architecture by Charles Moore and Gerald Allen. New York: Architectural Record Books, 1976.
- Elements of Architecture: From Form to Place by Pierre Von Meiss. New York: Van Nostrand Reinhold, 1990.
- Experiencing Architecture by Steen Eiler Rasmussen. Cambridge: MIT Press, 1962.
- "Form" by Adrian Forty in Words and Buildings: A Vocabulary of Modern Architecture. New York: Thames and Hudson, 2000: 149-172.
- "Form and Formalism" by David Smith Capon in Architectural Theory: Le Corbusier's Legacy. Chichester: John Wiley & Sons, 1999: 41-70.
- The Measure of Man: Human Factors in Design by Henry Dreyfuss. New York: Whitney Library of Design, 1967.
- Towards a New Architecture by Le Corbusier. New York: Payson and Clarke, 1927.