The Louis I. Kahn Building

In director Richard Brown’s “Pre-Architectural Program,” an initial list of important considerations for generating ideas, he specifically stated that “natural light should play a vital part in illumination.” This stipulation, along with Kahn’s own strong interest in the use of natural light, resulted in Kahn’s early concept of a room with a vaulted ceiling that would allow natural light to enter the space from above.

Natural light enters through narrow plexiglass skylights along the top of cycloid vaults and is diffused by wing-shaped pierced-aluminum reflectors that hang below, giving a silvery gleam to the smooth concrete of the vault surfaces and providing a perfect, subtly fluctuating illumination for the works of art.

The main (west) facade of the building consists of three 100-foot bays, each fronted by an open, cycloid-vaulted portico, with the central, entrance bay recessed and glazed. The porticos express on the exterior the light-filled vaulted spaces that are the defining feature of the interior, which are five deep behind each of the side porticos and three deep behind the central one.

One of the architect’s fundamental tasks is formulating the structure, or arrangement of forms, that the building will assume. Each architect has an individual approach to developing that initial concept. Kahn is often quoted as first asking, “What does this building want to be?” He believed that the essence of the structure started with the room, and thinking about how that space would be used and how it should feel. From that point, the building evolved as a “family of rooms” with a simple plan based on classical proportion, repetition, and variation.

Like classical buildings (such as the Parthenon), the Kimbell’s structure is based on a consistent mathematical model. The basic plan is composed of sixteen cycloid vaults (100 x 20 feet) that are arranged in three parallel units of six, four, and six in the Kimbell. Other elements are based on a ratio of 20 to 10. For example, on the floor, wood sections measure 20 feet and travertine sections are 10 feet. The building is based on these “rules” of logic, enabling the visitor to easily follow and “read” the structure.

Although the structure is based on a simple plan of unadorned, repeated forms, Kahn also introduced variations on those basic forms and “themes.” The porticos at the Kimbell’s entrance on the west side of the building first introduce the vault to the approaching visitor and demonstrate the form’s versatility. Within the museum, visitors see that vaults cover the galleries, an auditorium, and the Kimbell Café.

Kahn preferred simple forms and natural materials. To achieve a sense of serenity and elegance in the Kimbell, Kahn selected materials that complemented each other in tone and surface: travertine, concrete, white oak, metal, and glass. Simple and unadorned, each of these materials shows its innate character by its variation of texture.

In the Kimbell’s galleries, concrete vaults shimmer with light to create a subtle luminosity that Kahn compared to a “silvery powdered moth’s wing.” Revolutionizing the modern use of materials, Kahn viewed concrete as both an aesthetic and structural choice. Reinforced concrete also supports the weight of the structure in the form of vaults, walls, and piers. Creating the right look to the concrete was a matter of serious importance to Kahn, who went to great lengths to select the proper color (soft gray with lavender tones) determined by the mixture of sand and cement. Numerous wall tests were poured and allowed to cure in the Texas sun until they found the right surface qualities and perfect match for the soft tones of the travertine. Kahn believed that buildings should tell the story of how they were made and that incidents of the construction process should be left as a visual record. Accordingly, when they occurred, marks from plywood mold forms, bits of rubber, and air pockets remained for all to see (although the workmen practiced to attain perfection).

Travertine, on the other hand, acts only as “in-fill” material. Kahn even called it wallpaper. The travertine (a type of colored limestone) used for the Kimbell was imported from Tivoli, near Rome, Italy. Despite its “Swiss-cheese” texture, travertine is a durable material and has been used since antiquity for countless buildings. Kahn used materials such as travertine to emulate the timeless and monolithic qualities he so admired in ancient structures. Over one million pounds of travertine sheathe much of the Kimbell’s interior and exterior walls, gallery floors, porches, and stairs.

Lead was selected for the roof cover for its color, dull sheen, and discreet, natural appearance. Because this soft metal ages quickly, Kahn believed that it would look consistent with the travertine and concrete. In keeping with his palette of warm and cool tonal harmonies, Kahn also selected white oak for the gallery floors, doors, and cabinetry; anodized aluminum (a light-weight metal noted for its high reflectivity that has been covered with a protective oxide coating) for the soffits and reflectors; and mill-finished steel for windows and door frames, elevators, and handrails, as well as in the kitchen, conservation studio, and darkroom. The Kimbell’s uniquely shaped handrails are made of folded metal, because Kahn preferred emphasizing the sheet quality of the material instead of pretending that it was worked like a solid material, such as wood.