Metal Architecture Home

Mixing Exterior Materials

Metal’s versatility allows it to easily mix with other materials

Mixing Materials Fort Riley Jan18
Designed by LEO A DALY, each of the materials selected for the Irwin Army Community Hospital serves a function, harmonizes with its unique context and works together to form a cohesive whole.

Metal’s versatility is one of the many reasons it is a popular building material. In fact, it’s such a versatile product it looks good next to many other building products, including wood, brick, limestone, EIFS, concrete and much more.

There is no magic number when it comes to the number of different products you can have on the exterior of a building, but most architects agree that too many can cause a project to look too busy and overwhelmed. Jon Fliege, AIA, NCARB, senior architect and director of design in LEO A DALY's Omaha, Neb., office, says it depends on the size, character, use and the story the building is telling. “Simplicity is always a virtue in design, and we seek to create buildings that can be easily understood, appreciated and used,” he says. “That doesn’t necessarily mean limiting the number of materials, but choosing materials that sing together and express a singular idea.”

Thierry Cassan, AIA, principal at Kruger Bensen Ziemer Architects Inc., Santa Barbara, Calif., agrees, saying that while architects often use mixed materials on exteriors, he personally follows the basic architectural principal of avoiding more than three materials on the exterior, since using more than three can create visual clutter and blight.

According to Jeff Goodwin, AIA, LEED AP BD+C, principal at BAR Architects, San Francisco, materials are one key aspect of the many decisions that must come together collectively to make a successful building. “We use materials to highlight elements like function, massing or expressed structure,” he says. “It is also an excellent way to add visual interest.”

When conceptualizing a project, Goodwin says they find it easier to start with fewer materials and add more only when they enhance the building’s diagram or aesthetic. “We frequently include metal as one of these core materials because of its flexibility in finishes, good durability and highly sustainable qualities,” he adds.

While using too many different materials can overwhelm a small building, a larger facility may be able to pull off multiple types of products. “For a large facility like Irwin Army Community Hospital [in Fort Riley, Kan.], we used a range of materials that express the landscape: natural Kansas limestone in three different finishes, precast concrete, local brick, a glass-and-aluminum curtainwall system, an aluminum metal panel system, and steel trusses to protect against progressive collapse,” Fliege explains. “Each of these materials serves a function, harmonizes with its unique context and works together to form a cohesive whole.”

Boulder Residences

Rendering of the downhill Boulder Residences at Northstar Resort in Truckee, Calif. Designed by BAR Architects, painted and Corten steel contrasts against natural materials like wood siding and board-formed concrete.

Design Context

A building’s site and location are also key to choosing its exterior materials. Especially site context, which informs all design aspects of a project. “Materiality is one of the more crucial elements that define a relationship of a building to its surroundings,” Goodwin says. “We take a different approach to material selection for a mixed-use project that is integrated into an existing urban fabric than a private residence that is in a less developed or more rural area,” Goodwin explains. “Achieving an appropriate level of contrast to the site and any existing buildings is also important.”

For the hospital, Fliege says that meant doing extensive research into the history, archeology and geology of the site to inform a design that fit into its context. “We considered not just styles of architecture and the materials surrounding the hospital,” he says, “but how these styles and materials shifted over time as needs and construction methods changed, and the effect those changes had on the overall character of the campus.”

Rather than default to the current architectural guidelines of the fort, Fliege says they used the history of the architectural elements to inform a design that respects both the fort’s limestone architecture and the mid-century aesthetic of precast concrete and red brick. “On the side facing the historic fort, we emphasize the use of natural Kansas limestone,” he explains. “One the side facing the barracks, we emphasized the use of precast and local brick.”

However, in using metal panels, Fliege says they broke from the fort’s design criteria of brown-sloped roofs, and instead chose a silver brushed aluminum system that adds a sense of lightness to the top floor. Since the upper floor is a mechanical penthouse that requires a lot of airflow, they chose louvers that matted the same silver color family of the metal panels.

Using particular types of metal and metal finishes can also be dependent on where a project is located. “For example,” Cassan says, “many of my buildings are located on the California coast, and the combination of salty air and humidity can be corrosive and damaging to some types of metal.”

Law Winery

Site and function drove the materiality of the Law Winery in Paso Robles, Calif., designed by BAR Architects. The palette consists of cast-in-place concrete, natural Corten steel cladding, painted and galvanized steel structural framing, corrugated metal siding, exterior stucco and a standing seam metal roof.

Form Follows Function

Beyond fitting in to its site and location, materials can help create an ambiance and experience for the users of a building. “We tend to choose materials that create a warm, inviting aesthetic across our many project types,” Goodwin explains. “Our goal is to also balance this with the more practical limits, such as durability needs, passive sustainable design, etc.”

And durability is essential for a medical facility like Irwin Army Community Hospital. “In the event of a tornado or some other catastrophic event, people tend to gather at the hospital, and it needs to be there to treat the sick and injured in the aftermath,” Fliege notes.

To achieve that goal, the hospital was designed with a number of anti-terrorism/force protection measures, and is the first hospital to meet the Army’s new standards for progressive collapse. “We used heavier masonry materials where those threats are more common, and set the glass curtainwall back from the street,” Fliege explains. “To meet the progressive collapse standard, we strengthened the structural system behind the curtainwall in a way that wouldn’t take away from the aesthetic or function of the building. Rather than using thick steel beams, which would have blocked sunlight and views, we took a sculptural approach, using steel trusses.”

For the Law Winery in Paso Robles, Calif., Goodwin explains how site and function drove the materiality of the building. “A contemporary interpretation of a California working ranch, the design provides visitors with a natural, elegant and welcoming experience,” he says. “Building materials were selected for durability, ease of maintenance and appearance; many were employed in their natural state as the finished surface. The palette consists primarily of cast-in-place concrete—both board-formed and smooth surface—natural Corten steel cladding, painted and galvanized steel structural framing, corrugated metal siding, heavy dash, integral color exterior stucco and standing seam metal roof.”

On the first permanent buildings for the new  Santa Clarita Community College, Canyon Country campus in Santa Clarita, Calif., Cassan shares that sun exposure is an important issue. “One of the budget-driven strategies we employed was to extend the structural floor framing past the exterior walls to create shades on the building’s envelope,” he says. “This solution not only addresses the sun exposure issue, but also allows for cost efficiencies (as it eliminates the need for costly specialty materials such as pre-fabricated sunshades) and at the same time creates visual interest on the building’s exterior. In this way we employ structural steel as a metal element in the building’s exterior, as opposed to an add-on metal element, which is more likely to be eliminated during value engineering.”

Another example is the Boulder Residences in Lake Tahoe, which is scheduled to be competed this spring. According to Goodwin, the project involves a series of ski-in/ski-out townhomes located mid-mountain at the Northstar Resort in Truckee, Calif. “Here, both painted and Corten steel are used again, contrasted against natural materials like wood siding and board-formed concrete,” he says. “Simple building forms aim to integrate the homes with their natural surroundings allowing a very limited palette of exterior materials to create warm, yet contemporary, outdoor spaces.”

Santa Clarita Community College

Structural steel is used as a metal element on the exterior of the new Santa Clarita Community College, Canyon Country campus in Santa Clarita, Calif., designed by Kruger Bensen Ziemer Architects Inc.

A Versatile Aesthetic

Metal provides architects and designers with a versatile aesthetic, coming in a variety of colors, shapes and textures. Additionally, it is durable, affordable and sustainable. Using metal allows architects many options to achieve a vision for a building.

“As a designer,” Casssan says, “the versatility of metal is even more paramount to architectural composition. No matter what a building’s intended purpose is, metal allows for the expression of that function through an infinite variety of forms, making it even more attractive as a choice for the exterior envelope, whether as a sole material or in conjunction with other compatible materials.”

“We love using metal because of its durability and variability of finish options,” adds Goodwin. “It works well with other materials, making it a highly versatile option. It’s an exciting material because there are constantly new products being developed that improve functionality and offer opportunities for added creativity."