Story at a glance:
- Exterior wall cladding materials have expanded to include the unexpected, from innovative terra-cotta to MCM.
- Brick continues to be a popular cladding material for its durability and inherent thermal properties.
- Many architects choose wood for its aesthetics, including sustainably sourced wood that’s specially modified.
Exterior wall cladding materials have evolved beyond the perhaps more expected brick or wood. While brick and wood continue to be beloved, architects and designers are also turning to solutions like metal composite material and exciting, innovative terra-cotta solutions.
Here are some of the most popular exterior wall cladding materials and why architects today should consider these options.
Skidmore, Owings & Merrill (SOM) chose a surprising black glazed terra-cotta from Shildan Group for its 2022 project, 28&7, in Manhattan. The 28&7 facade draws inspiration from the neighborhood—an area rich in 19th- and 20th-century masonry buildings, with a cladding selected for both its customizable and sustainable properties.
“We knew from the get-go that we wanted a black building,” said Michael Kirchmann, CEO and cofounder of GDSNY and a former SOM architect, in a previous article for gb&d. He said the black punctuates the building’s prominent corner in a way that gives it even more presence.
SOM had worked with terra-cotta before, collaborating with Shildan Group on another NYC project that incorporated white glazing. When it came time for 28&7, the team knew they wanted something special. They returned to Shildan to push the envelope even more. “We were looking for extra depth and extra reaction to the light—and to do that in a way that was contrasting with the context, which is a very neutral buff tone masonry,” said SOM Design Partner Chris Cooper.
Shildan Group has seen a demand for three-dimensional shapes and an expansion of where terra-cotta can be used—including on curtain walls, according to Shildan Group President Moshe Steinmetz. “No more of those boring, rectangular aluminum extrusions but really introducing cladding to those volumes to make a building much more interesting,” he told gb&d.
“Not only is brick almost entirely recyclable, but it’s a building material that can be retained when a building undergoes a full renovation,” writes Tim Leese, director of marketing for Glen-Gery, in a previous article for gb&d. “Building codes further support reuse as an exterior cladding material in other buildings when the bricks retain their original properties and have their structural capacity intact.”
Brick also makes for more energy-efficient projects, as bricks have inherent thermal properties because the clay from which they are made is a high-density material. Leese says brick can absorb and store heat energy in both the summer and winter to better cool and heat a home, in turn helping to minimize large peaks and dips as a home’s temperature fluctuates, instead averaging out extremes.
Building with bricks also allows for virtually no emissions, he said. And, he said brick is incredibly resilient, weather- and storm-proof, and low-maintenance.
For exterior cladding, it’s important to use woods that are “stable,” according to Delta Millworks CEO Robbie Davis. That means they maintain their straightness and flatness when there are changes in temperature, humidity, and exposure to the elements like sun, rain, hail, and so forth.
Davis previously told gb&d Delta’s exterior woods—including its specially modified products like Accoya and Kebony, its shou-sugi-ban line that involves a Japanese charring process, cedar, and its newest thermally modified Mojave collection (available in oak, hemlock, radiata, and Ponderosa pine)—are far superior in quality to those typically sold at home centers. You’ll spend a bit more upfront, he said, but it will save you significant money, time, and headaches down the line.
All of Delta’s wood is sustainably sourced, and a good portion of its domestic product comes from tree farms in British Columbia. That means there’s no clear-cutting involved, less long-distance shipping, and a smaller carbon footprint than those produced by many other wood harvesters in America and abroad.
Testing, too, is a vitally important part of the Delta process. Each product is subjected to artificially emulated extremes—high up in the dry mountains of Colorado, for example, or near the humid coast of California—with an accelerated weathering machine to make sure treated wood and coatings can easily endure the harshest real-world conditions. That way, there are no surprises once it’s installed, and clients can be assured of its future performance.
Metal Composite Material (MCM)
MCM is a cost-effective cladding solution more architects are turning to, as lightweight sheets can be fabricated into complex shapes, finished in a wide array of colors and designs, and provide a steadfast cladding option that, combined with insulation and air water barriers, creates a high-performance building envelope, according to Michael Bowie, technical support specialist at MCA-ALPOLIC Division.
“Introduced to the world more than 50 years ago, American manufacturing and architectural use of MCM has taken hold over the last three decades,” Bowie previously wrote for gb&dPRO. “First incorporated into gas station canopies, painted aluminum composite material (ACM) offered a lightweight, uniform look for the biggest petroleum brands who needed easy fabrication, reliability, and custom matched finishes for their corporate identity colors.”
He said the panels can be fabricated in the shop and installed faster than alternative products for the building envelope. “These systems could require less structural investments, like reduced steel needs because of the lighter load in the wall assembly. Though only one-fourth to one-third as much metal as comparable one-eighth inch sheet metal, composites impressively retain their rigidity and strength.”
Experts are also seeing a growing demand for ventilated facades in the architectural community.
Why a ventilated facade? Simply put, a ventilated building envelope—defined as cladding designed with an internal air chamber—allows for both increased thermal and acoustic performance, reducing energy costs for heating and cooling, and with less ambient noise making its way in, improving the lived experience inside the structure. Properly designed ventilation can increase the resiliency of a structure by keeping building materials dry at all times, while using thick ceramic tiles help the structure resist against direct environmental loads such as wind, rain, and heat. Combined with a rainscreen, a time-tested building practice, ceramic facades can last generations.
Innovative Metals Company (IMETCO), a leading US manufacturer of premier metal products for the building envelope, has experienced this demand firsthand.
“Lighter, easier to install, safer for buildings (with no contribution to fire risk), and endlessly customizable, this cladding system sets a new industry standard,” Juan Gurrea, export manager at Gresmanc, previously told gb&d. “And it can be combined with various materials or seamlessly integrated into IMETCO’s innovative IntelliScreen rainscreen systems.”
Perhaps unexpected, vinyl siding continues to be a popular—and increasingly sustainable—choice. “Vinyl siding is probably the most sustainable product from a complete life cycle perspective of any exterior cladding,” said Steve Booz, vice president of marketing at Westlake Royal Building Products, in a previous interview with gb&d. “The resources to manufacture it are lower, and certainly the longevity and the recyclability of the material make it one of the most full-circle sustainable solutions out there.”
Westlake Royal Building Products’ TruExterior product line is made from 70% recycled content—specifically fly ash, which is a by-product recovered from coal combustion—combined with polymer for a high level of dimensional stability and durability.
“Customers want a product that is going to last a lifetime,” Booz said. “That’s why our siding products at Westlake are engineered with advanced materials that offer a wood-like aesthetic without the moisture absorption or maintenance issues associated with real wood products. When moisture penetrates materials like wood and then dries out, it can lead to cracking, warping, and mold growth. And customers just don’t have time to deal with those issues.”