Architizer + NBK Terracotta explain the ins and outs of designing with terracotta
Terracotta, an ancient building material once suited to adorn the Babylonians’ palaces and temples, is a buzzworthy, customizable and durable façade option. Architizer describes the long, sustainable lifecycle of this natural material; details its storied past; and offers insights on specifying a range of terracotta options in a recent feature with Christian Lehmann, Ceramic Engineer and General Manager of NBK North America.
Lauded for both its sustainable and highly flexible design properties, terracotta offers virtually endless opportunities to create custom façades through a wide range of colors, glazed and natural finishes, and textural patterns. In recent years, Renzo Piano was one of the celebrated architects who revived it, pushing its limits in large-scale, high-profile projects. Piano’s noteworthy 1997 project, Potsdamer Square in Berlin, prominently featured a “bespoke curved terracotta façade,” Architizer explains.
“Renzo Piano’s projects were breakthrough,” says Lehmann. “The big difference was that Renzo Piano had a lot of ideas about shapes and sizes, which showcased the adaptable and geometric possibilities of architectural terracotta.”
While terracotta is famous for its earthy red color, it actually can naturally take on a light cream to dark grey pigmentation. Building off its natural state, adding pigments and glazes can produce brilliant yellows, purples, greens, deep reds, and blues. The options are literally unlimited.
Jim Olson, principal architect at Olson Kundig, opted for an eye-catching golden-colored terracotta exterior at Denver’s Kirkland Museum of Fine & Decorative Arts. The museum, which is aptly located in the city’s Golden Triangle Creative District, opened in March and features NBK’s terracotta baguettes in an array of yellows that complement the colorful art housed inside. Meanwhile vitrines, which are mounted to the façade, spotlight decorative objects, and literally bring the art to the street. It’s an exterior that “in particular commands attention” with its “irregular verticals in four shades of golden terracotta in a jazz-like rhythm,” writes Metropolis Magazine.
Perkins + Will added eye candy to an underprivileged Toronto neighborhood by wrapping the Albion Library in five brightly-hued shades of two-inch-wide slats of terracotta. The friendly, colorful design in bright orange, chartreuse, purple and cream features a mix of both TERRART Large and Baguette glazed and natural vertical tiles, and acts as an ode to the many book spines that fill the library inside.
Another project, Salt Lake City’s Marmalade Library, creates an interesting effect by showcasing TERRART natural clay red and stone white shaded baguettes through a fresh, unexpected stacked arrangement that provides solar screening by day and offers a lantern-like glow by night. The library earned Best Project recognition in the small-project category from ENR.
“You can mix red and white clay to get lighter reds or even yellowish clays,” Lehmann explains. “To get a little bit higher variation, you can add pigments or oxides. Through firing these pigments at a temperature of about 2,000 degrees-Fahrenheit, they will react with the clay, creating stable and long-lasting colors. You will not really see a difference in color over 50 or even 100 years… In comparison, we are seeing many fiber cement façades losing color and fading; with very high color stability, terracotta won’t change color for decades.”
Glazed effects can vary from “a very transparent glaze where you still see the body color underneath or a completely opaque glaze that you cannot see through at all,” Lehmann tells Architizer. “You also have the option of choosing between very high gloss and completely matte finishes. By combining two or three glazes on different layers of the product, other special effects, including iridescence, are also possible.”
Further customization comes into play through terracotta’s ability to take on different textural finishes. These include adding personality through fine-peeled, peeled, fine-combed, medium-combed, sandblasted and honed finishes. The Liberal Arts Building, at the University of Texas’ Austin campus, is clad in a terracotta that offers the clean, minimal look of limestone at a more attractive cost. The smooth, creamy-colored TERRART Light terracotta features the added design touch of a honed textured finish.
“What I really hope to do is work with creative architects who will challenge us and the possibility of terracotta as a building product,” Lehmann reflects.
NBK’s work at the University of Kansas’ Health and Education Building illustrates the versatile range of application of terracotta from functional to artistic. Here, natural orange-hued TERRART baguettes appear inside a glass façade, acting as an architectural embellishment instead of cladding the exterior. Functioning as a design element, architects referred to the decorative screen formed by narrow terracotta baguettes as “The Cloud.”
“If you look at the product, which is basically a mix of clay and water, there are no chemical additives. We aren’t including any fibers to make it stronger — it’s just nature,” Lehmann reflects. We are doing what people have been doing for the last couple thousand years, just with more modern processes and technology. It is really a proven material.”
For details on specifying different types of terracotta and to learn more about its sustainable properties, check out the full interview on Architizer.