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Perforated and Expanded Metal Updates

Nine things you should know about these building components

Atas Mar18 1

Even though perforated and expanded metals have been used in construction for over 100 years, architects, designers and builders continue to find new applications for them and their usage is growing. Here are nine things you should know about these two building components.


Recently, there has been increased demand in both architectural and security applications for expanded metal. “The advantage of expanded metal for security applications is increased strength and difficulty breaching compared to chain link,” says Drew Bahner, vice chairman of Expanded Metal Manufacturers Association (EMMA) and general manager of Expanded Solutions LLC, Oklahoma City. “It also works well behind drywall to prevent business-tobusiness building breaches.”

Bill Phillips Jr., president/COO of Niles International, Niles, Ohio, says expanded metal has new applications in and is quite functional for absorbing specific sound frequencies, EMI/RFI and microwave containment, control of design, control of lighting, control of ventilation, control of sound and the fabricating/structural considerations of open area. “Other unique applications for expanded metal are in foils with lightning strike protection, fuel cells, filtration and medical,” he adds.

From a design perspective, perforated metals are becoming more popular in parking garage applications, for sunshading elements and accents with backlighting, according to Jim Bush, vice president of sales, ATAS International Inc., Allentown, Pa. “In some cases, corporate images with customdesigned perforations are also requested,” he says.


Some believe expanded metal is the greenest type of open area metal on the market today. While it looks like expanded metal is punched, it is actually slit and stretched in one motion and there is no scrap generated in the process. A typical expanded product expands the raw material more than 300 percent; however, depending on the product, this can vary. “When perforating a 4-foot by 8-foot sheet, you get a 4-foot by 8-foot sheet of perforated along with all of the punched scrap,” Bahner says. “Both expanded metal and perforated metal are cold processes utilizing mechanical energy and dies and require no welding. Yet another type of open area metal would be metal bar grating, which, like expanded metal, doesn’t create scrap in its process. However, metal bar grating does use a significant amount of energy since it is a welded product. The lower environmental impact also generally translates into a lower overall cost.”

Production processes for expanded metal create zero waste. “[It] actually conserves (stretches) raw material input by up to five times, resulting in less material consumption and a reduced carbon impact,” says Michael J. Gilboy, president, Spantek Expanded Metal Hopkins, Minn. “Use of expanded metal as a sunshade or a building envelope can greatly reduce interior cooling cost, while maintaining beneficial solar gain for heating cost reduction.” Expanded metals enhance interior building environment quality and strengthen the relationship between indoor and outdoor spaces. Expanded metal mesh provides a medium through the introduction of filtered day and night views, along with control of heating, cooling and lighting. All of this while maintaining visual transparency in a desired direction.

Using expanded and perforated metals helps attain recycled materials credits. Phillips says material and resource (MR) credits are available for construction waste management, recycled content and use of regional materials. “The greatest portion of Niles’ products help to achieve such credits,” he adds. “Energy and atmosphere (EA) credits using Niles’ architectural meshes for shading on interior sections and exterior facades of building design can help to reduce solar effect and energy required to run HVAC systems.”


Many different metals can be perforated. Bush contends aluminum is the desired material due to its inherent corrosion-resistant properties. He feels this is especially true with exposed cut edges at the holes or penetration locations. Bahner agrees that aluminum is popular because it doesn’t rust and doesn’t require paint.

Expanded mesh is available in most any ductile metal, alloy, plastic and polymer. Phillips says common materials expanded by his company are aluminum, brass, bronze, copper, carbon steel, nickel alloys, platinum, silver, stainless steel and titanium.


Designers are further stretching the boundaries of aluminum by adding colors with an anodizing coating. Expanded metal is also available in original mill finish, powder coating and polyvinylidene fluoride (PVDF) finishes. Phillips says coatings available in secondary treatments completed after the expansion process include Corten, hot-dip galvanizing, and painting and plastic coatings. Bush says for materials other than corrosion-resistant materials such as metallic-coated steels, it may be desirable to post paint the material after perforating because the primer and paint coating can provide some element of corrosion protection at the cut edges of the perforations.


Limitless pattern choices with expanded metals are providing a wider range of open-area options and opening apertures. Also, expanded metal is more than just a 2-D product, it is also 3-D. Phillips says, in its 3-D (raised) form, the sheet offers four views depending on how you view it. Gilboy believes these 3-D patterns provide a unique and creative means of filtering light, while providing a striking visual appearance.

Other features available are solid and ribbon sections in the finished sheet parallel to the expand direction. Bush says in addition to perforated metal round holes, there are also slots, ovals, rectangular and square perforations are also coming into the marketplace.

Oakdale, Minn.-based Pure + FreeForm captures depth by layering multiple designs in different colors, patterns, textures and gloss levels. “Our Lumiflon resins allow a broader range of textures and gloss, from super matte to automotive reflective, in comparison to other industry standards,” says Geoff Hahn, creative director at Pure + FreeForm. “Not only can our flat, prefinished sheets of aluminum be bent to create dimensionality, our unique printing technology can also be manipulated to achieve an optical illusion.”


Designers must be aware of and consider the structural characteristics of the formed panel or sheet/ plate. “As metal is removed during the perforation process, you will lose structural performance of the materials as compared to a solid sheet,” Bush says. “This may be partially offset by a reduction in wind loads on the cladding component (perforated panel) due to the perforations. An engineer should be consulted in the attachment methods of the cladding for code compliance.”


According to Peter Faulk, marketing manager at Bristol, Conn.-based Morin Corp., his company is constantly seeing new and creative uses for perforations. Morin produces a wide variety of hole options, and patterns, spot patterns and custom repeat patterns that work with roll- or break-forming panels for specific applications. “At Morin, we focus on more functional designs, but we do see graphic elements, laser die-cut, micro-perf and photo-perf imaging,” Faulk says. “Our ‘new’ is in new creative applications of similar processes, spot hole patterns and very creative uses.”

One outstanding example of Morin’s customization is its custom message hole patterns. “We did a fun job for a company used in a parking garage that had a pattern with a secret message in it, in Morse Code, relating to the company slogan,” Faulk says. To customize a panel for a stairwell, Morin used double-hole screening. “One pattern [had a] small hole—positioned as a sunscreen—and the other pattern larger for airflow and security and open air feel,” he adds.

Oakland, Calif.-based Móz Designs lets designers pick perforated metal, add a handcrafted grain and choose from six color collections to create a fully customized product that comes ready to install. Móz perforated metal is available in five standard profiles, with circular cut-outs that range from fine to bold. “For larger projects, Móz can customize shapes and sizes, add trims or use thicker gauge material,” says Tripp Sandford, vice president at Móz Designs. “Standard sheets come in a 4-foot-wide by 10-foot-wide by 0.063-inch diameter size and can cover any surface area with stacked or joined segments. [Our] handcrafted grains can be paired with perforated metal sheets to create mesmerizing effects. Choose from a shimmering waterfall of waves, fabric-inspired linen or organic textures, like bamboo. Unique etched grains provide a depth and distinction in metal surfacing.”

Many types of graphics can be incorporated onto metal surfaces either as custom perforation patterns or applied graphics. Pure + FreeForm’s mission is to produce site-specific and contextual designs, and Hahn contends all its finishes offered are fully customizable. “This applies not only the way we treat the surface with texture and design, but also corresponds to the perforation used,” he says. “Perforation itself has moved over the past decade from something utterly industrial to a means of providing a semiotic understanding of the site and the façade. Today, there are many perforation methods, from programmed CNC to fiber laser, rotary pinned, water jet cut or complex algorithms, that designers can select any level of customization at different price points.”


Phillips believes expanded and perforated metals are generally created on similar equipment. “Both share the same equipment manufacturers, although some expanded metal mesh manufacturers make their own equipment. The differences are perforated starts and finishes from the same size sheet and expanded can produce up to five times more mesh from the same size sheet.”

Perforated metals are most commonly punched using a multiple punch press application or specialty equipment such as a turret press. Forming of perforated panels is performed the same way a solid panel is formed.

Expanded metal is slit and stretched in a mechanical press. “One strand width is fed through the machine per cut,” Bahner says. “The dies then slit and stretch one strand. It takes two strokes of the machine to complete one design which is most commonly diamond in shape.” Gilboy says expanded metal sheets can be custom cut using traditional shears, laser, plasma, or waterjet methods. “This allows for custom geometry as well as traditional panel sizes,” he adds.


Once installed, when do perforated and expanded metal look or become outdated? “Never,” says John Reuter, president, Metals Inc., Oakwood Village, Ohio. “Perforated and expanded patterns aren’t necessarily ever dated,” he says. “These patterned materials in a variety of alloys can be powder coated, polished or anodized—just a couple of finishing examples—to give a lasting impression."