Powerful CAD software has given architects the ability to create mind-boggling forms. But it still takes the resourcefulness and ingenuity of fabricators such as the A. Zahner Co. of Kansas City, Mo., to make them constructable.
Zahner’s machines laser-cut and rolled the angel hair–finished stainless steel sheets covering Frank Gehry’s 2004 Jay Pritzker Pavilion in Chicago. The company’s presses punched the hundreds of thousands of holes and dimples that texture the solid copper face of Herzog & de Meuron’s 2005 de Young Museum in San Francisco. And semis laden with its prefabricated, perforated panels braved the urban lanes of New York City to clad Morphosis’s 2009 Cooper Union New Academic Building.
When the company decided to add a 6,200-square-foot, high-bay fabricating studio to its plant recently, it turned to a local firm, Kansas City’s own Crawford Architects, to design the structure. Zahner’s only requirement was that the design should make use of the company’s Zahner Engineered Profile Panel (ZEPP) system—which includes structural elements normally found unexposed beneath sheets of metal.
The façade’s Cloud Wall design was based on a pencil sketch made by Crawford project designer Stephen Colin, Assoc. AIA, which was inspired by the corrosion patterns he found on a piece of steel at the Zahner plant. The designers used Autodesk 3ds Max to create a three-dimensional model of the drawing based simply on its tonal values. The resulting form, in turn, was sliced into parallel sections, much in the way a magnetic resonance imaging machine renders a three-dimensional solid. Further separated, these vivisections determined the shape of the vertical fins that now articulate the addition’s north and east façades.
After small-scale study models were made, several of the fins were fabricated at full size for a mock-up. In section, each fin looks a bit like an I-beam, except that the flanges are made of a D-shaped aluminum extrusion. These extrusions are riveted on each side of a 3/16-inch-thick aluminum sheet that forms the I-beam’s web.
To shape the extrusions, Crawford imported final drawings of each fin into CATIA, using a proprietary algorithm. The software was used to control a machine equipped with rollers. After all of the extrusions and sheets were formed and riveted together, they were tempered using a process called solution heat strengthening—a process that gives the aluminum a bright appearance.
The fins were lifted into place by crane and welded to clips bolted to both the addition’s concrete foundation wall and the heavy structural steel frame that supports the rest of the studio. All of the rivets, screws, bolts, welds, and even pencil marks were left exposed and unfinished, just as they would have appeared underneath a sheet-metal skin—as they are typically used.
Insulated glass units were then installed between each pair of fins, flooding the new fabrication space with daylight. (“People don’t usually associate us with glass,” says L. William Zahner, Hon. AIA, “so we wanted to show we do that, too.”) The glass units were preassembled and then attached to the fin’s aluminium framework with fasteners. Several X-shaped “boomerangs” are engaged through a slot in each vertical fin and then bolted, providing lateral strength. Though the aluminum fins resist wind loads and hold up their own weight, they are not load bearing.
Crawford Architects principal Stacey Jones says that he is surprised that Zahner selected a local firm to design the plant. “He could have any architect in the world,” Jones says. “How great is it to have a material that is as malleable as metal, and then have a master craftsman like Bill Zahner stand beside you, helping you explore what’s possible?”