Curved metal framing immediately enhances the graceful organic appearance of an architect’s composition. The most common curved framing application is walls. Curved soffits are a close second, along with arches and barrel vaults. Artistic and asymmetrical structures have increased due to curved metal framing’s ability to accommodate them.
Until recently, the tools and techniques used to construct geometrically accurate curved metal framing did not exist. Since building products were previously only available in straight sections, many times building beauty was forfeited in favor of cost and ease of construction. Previous methods of creating curved surfaces, which included stretch forming or bending metal by hand, were either prohibitively expensive and often had inferior results.
Producing curves from a straight metal component was the biggest obstacle to overcome. The previous method of “cutting and snipping” involved cutting wedges out of a standard piece of track. It was time consuming, and locking the cut-up track shape and maintaining smooth curves presented additional challenges. Today, advances in technology have helped transition curve creation into a scientific, economical, duplicable process ensuring geometrically precise curved walls, roofs and other surfaces.
It is now easy to shape track and studs by hand, and complete the job by easily locking it in its new shape. “With the introduction of curvable/flexible components such as Flex-C Trac, many architects are now able to justify the incorporation of curves in their projects,” says Frank Wheeler, inventor and owner of Flex-Ability Concepts, Oklahoma City. “The actual construction of curved walls is virtually the same as constructing straight walls: metal top and bottom track, metal studs and covered with gypsum board. A contractor may want to use two layers of 1/4-inch gypsum board or even high flex gypsum board depending on the tightness of the curvature. He may also want to use closer stud spacing through curved sections to allow for more places to fasten the gypsum board to the framing.”
The Radius Track Bender is an important innovation that brought precision and control to curved metal framing. It was invented by Charles Mears, CEO and chief design officer at Radius Track Corp., Minneapolis, and introduced in the late 1990s for the Walt Disney Concert Hall in Los Angeles. The innovation offered a new way of accomplishing pre-curved members that were site-bent and shop-fabricated.
“This approach uses calibrated crimps, or bends, in the web and/or flange of standard steel tracks and steel studs to precisely curve members to match the design intent,” says Mears. “The technique replaced the stretch-form method with a more affordable and versatile approach. The interior framing used in the concert hall was no longer limited by pre-built forms, so a much broader range of curve options were available to the designers with dramatic results.”
Bending technology has advanced to a degree that most surface framing systems, including heavier structural stud and track elements, can now be efficiently produced with larger pneumatic and hydraulic benders. These machines, when coupled with the data extracted directly from 3-D computer models, can bend much heavier-gauge material and much deeper sections. The ability to curve track flanges independently of the track web adds the capability for compound bending configurations. This removes the final limitations on designers for all many compound-curved surfaces.
Many products can form curves but it is crucial to use a product that can be locked into a desired shape so that it maintains its shape when wall covering such as gyp board is wrapped around it. “Flex-C Trac comes in most any size from 2 1/2 inches and Angle up to 10 inches, and in all three gauges of 20-, 18- and 16-gauge,” Wheeler says. “Flex-C Arch works on the same principle but bends in the other direction.”
Radius Track uses cold-formed steel from 14- to 20-gauge track, studs, angle and hat-channel. The material can be easily bent and formed in the shop, using CNC equipment. “It can also be bent in the field using Radius Track hand tools, called Radius Track Trim Bender and Radius Track Bender,” Mears says.
Generally speaking, cold-formed steel is the common term for products made by rolling or pressing thin gauges of sheet steel into goods. In the construction industry both structural and non-structural elements are created from thin gauges of sheet steel. Cold-formed steel construction materials differ from other steel construction materials known as hot-rolled or “red iron” steel. The manufacturing of cold-formed steel products occurs at room temperature using rolling or pressing.
In addition to new innovative physical tools that allow users to create curves, new software tools are ensuring that what users see on the computer screen is what they get at a job site. Installation is made easy using color-coded members and detailed installation instructions.
At early project stages, BIM technology lets users identify clashes with other trades, such as HVAC, acoustical and plumbing. “When working with curved surfaces, it’s particularly difficult to anticipate where these systems need to intersect with walls and ceilings,” says Mears. “Unlike working with plumb walls and ceilings, curved surfaces require identification of XYZ coordinates that are usually in mid-air. When applicable, these XYZ coordinates can be used with such equipment as a Total Station, to help the trades identify these points in space during the building process.”
The growing number of sizes and gauges available, along with videos and on-line tools are helping increase curved metal framing usage for the design and layout of curves, arches and domes. “Architects and designers are now well aware of curvable/flexible components,” says Robert Widmer, marketing manager, Flex-Ability Concepts. “They are feeling freer to unleash their creativity. Mushroom and spiral ceilings, wavy and twisted walls are examples of designs making their way into modern construction. Architects also know their more creative designs are not only possible but easier than ever to construct. It is the contractor utilizing curvable/flexible components, such as Flex-C Trac, that is best prepared to make these designs into reality.”
