Story at a glance:
- Terra-cotta is experiencing a renaissance as a sustainable material in architecture.
- The material’s ability to be customized in shape, size, and color makes it ideal for creating expressive facades.
- Now researchers are using terra-cotta in innovative new ways, from floor tiles to window mullions.
Terra-cotta, Italian for “baked earth,” has been used for thousands of years. In the last decade the versatile material has surged in popularity as architects experiment with environmentally sustainable and creative new applications for it.
Here are just some ways to use terra-cotta in architecture.
1. As a Sustainable Material for Roofing
Tyler Arboretum’s living classroom building is entirely clad in terra-cotta tiles from Ludowici. Photo by Halkin Mason Photography
While shingles are an oil-based product, terra-cotta is a natural mixture of dirt, shale, and water. This makes terra-cotta one of the best sustainable roofing materials. Although heavier than shingle, terra-cotta tiles’ durability gives them century-long lifespans.
Terra-cotta’s low moisture absorption rate also makes it an ideal material for roofing. These properties have made them a synonymous material in cities across Europe and Asia, as well as an increasingly popular material in North America.
Terra-cotta is also incredibly tough and weather-resilient, says Rob Wehr, vice president of business at Ludowici, in a previous article for gb&dPRO. “Through superior raw materials, profile engineering, and the manufacturing process, Ludowici tiles are made to withstand more stress than any other clay tile product on the market. The production process allows tiles to form into a dense, vitrified material with the highest strengths available—essential for peak performance.”
Ludowici has been crafting architectural terra-cotta products since 1888 and recently updated the University of Chicago’s iconic English Gothic roofs. “When it comes to weather performance, not all tile is the same. The clay composition of our tile creates an ultimate breaking strength able to resist high wind stresses experienced during extreme weather events. When properly installed, Ludowici terra-cotta tiles can sustain high winds, fires, moisture, salt intrusion, and more.”
Switching to circular, cradle to cradle materials that don’t produce waste is a change that makes it easier for projects to achieve a higher LEED certification. From the start of its lifespan terra-cotta produces no waste in its manufacturing process. It lasts a long time with minimal maintenance, and, because it’s a natural material, at the end of its lifespan it can be fully recycled. This gives terra-cotta a much lower embodied energy than other materials like steel, glass, and concrete.
2. As an Architectural Expression
The facade at 28&7 was manufactured in a zero-waste, low-energy process, designed by Shildan Group with a custom glossy black glaze that visually highlights the structural grid. Photo by Dave Burk, courtesy of SOM
Terra-cotta’s ability to be customized in shape, size, and color makes it an ideal material for architectural expression in a building’s facade. This isn’t a new idea in architecture. The Reliance Building in downtown Chicago, one of the world’s first skyscrapers, is clad in bright white, ornamented terra-cotta, giving the building an appearance of effortless lightness.
With the emergence of the steel, glass, and concrete buildings of the International Style in the 20th century, terra-cotta lost its popularity as a material. Today the material is experiencing a resurgence of popularity with architects for its low environmental impact and customization potential. SOM’s elegant 28&7 office building in the Chelsea neighborhood of Manhattan uses custom reflective, black-glazed terra-cotta to create a tapered facade that finely tapers between floors and shimmers in the daylight.
“We were very enamored with terra-cotta as a material,” SOM Design Partner Chris Cooper said in a previous gb&d interview. “It is having a real renaissance in its modern form of extruded terra-cotta versus the historic pressed terra-cotta we know from all around the city. We like that it’s a natural material, but it’s also a very versatile material.”
Terra-cotta’s historical legacy allows architects to use the material to reference the material heritage of the cities they work in. SHoP’s 111 West 57th Street, one of the tallest residential buildings in the world, references classical New York City architecture with its curving white terra-cotta and bronze facade.
Conversely, the Tyler Arboretum Edible Gardens in Delaware County, Pennsylvania uses terra-cotta’s natural clay-red hues to give the site a natural aesthetic reminiscent of a garden pot. DIGSAU architects clad the building entirely in the material, meaning that with time the tiles will become host to a variety of pollens and mosses, enhancing the building’s organic qualities.
3. As a High-Performance Facade
Shildan Group worked with Office 52 Architecture on the University of Oregon’s Tykeson Hall. Photo by Sinziana Velicescu
Although conventionally associated with roofing, terra-cotta also has a long history of use in building facades. Compared to its all-glass glazed counterparts, terra-cotta’s significantly higher thermal mass gives it better thermal performance by buffering against extremities in outdoor temperature. Architects also use terra-cotta as an alternative to glass to reduce the window-to-wall ratio of a building, allowing for greater energy efficiency and a more expressive facade.
Terra-cotta was also used at the turn of the 20th century as a natural rainscreen in high rises, but the system fell out of fashion with architects until the late 1990s, when rainscreen and sunscreen suppliers like Shildan Group introduced new systems to the market.
An open joint terra-cotta rainscreen both reduces the material use (and thus embodied carbon) of a project and allows for healthy walls with plenty of ventilation. Because the tiles aren’t held together with sealant or mortar, the system can be easily installed and repaired when damage occurs to the building’s exterior.
“I told them to leave the joint there. You don’t need to caulk or seal it. Leave it open and use terra-cotta to make the facade beautiful and healthy,” Shildan Group President Moshe Steinmetz previously told gb&d. “People looked at me like I was crazy and thought it would never work.”
4. For Interior or Structural Applications
Boston Valley Terra Cotta produced architectural terra-cotta for the facade of The Fitzroy. Photo by Jimmi Billingsley
While terra-cotta has traditionally been too thick and heavy for interior applications, manufacturers are developing new resilient and lightweight forms of architectural terra-cotta (ATC) that can be used for flooring, bathrooms, and a variety of other indoor surfaces.
The Architectural Ceramic Assemblies Workshop (ACAW) explores new applications for the material in buildings. At ACAW 2021 a team composed of members from HOK, TriPyramid Structures, and the Gartner Division of Permasteelisa North America experimented with using terra-cotta as window mullions, post-tensioned with interior stainless steel tendons. Clay in general has a high compressive strength, so with the addition of another material such as the stainless steel tendons to provide tensile strength it can serve as an efficient structural system.
The role that ATC can play in this is considerable and is a driver in much if not all of the projects developed at ACAW. Importantly, ATC is now more than ornament and rain screen: It can be a part of the structure, a lighter weight and lower-carbon replacement of aluminum, steel, and concrete in many parts of a facade. And just as important in this era of buildings-as-sculpture, it brings color and glaze to the infinite variety of forms.
