
Metal being curved via a 16-foot plate roller. (Photo courtesy of MillerClapperton)
Curved metal panels let architects and designers add unique and functional features to their projects that can modernize and transform the look of any building. Taking advantage of metal's malleable properties, curved roofs, arched canopies, undulating waves, and curved column and walkway covers are possible.
The Process
Ken McLauchlan, director of sales and business development,Drexel Metals, a Carlisle company, Denver, explains that metal panels can be curved many ways with several different methods. “The most current is using equipment to mechanically curve to stretch the seam. Panels can also be curved directly out of the rollformer—sometimes accidently—by adding pressure to the panel in the tooling stations or as it exits the machine. This is usually only possible to a 90-degree radius and convex in application. Corrugated metal panels have been curved as well by mechanically stretching to achieve both convex and concave [shapes].”
Ben Kweton, vice president ofSheet Metal Supply, Grayslake, Ill., says, “Metal is curved by either cutting relief notches or by shrinking or stretching metal to conform to a curve. The former can be done as simply as using a pair of snips on a job site, or by a mechanical notcher or even a laser cutter, the latter done by anything from a hand-powered press to an air- or motor-driven unit. Either way, they use a die to either shrink or stretch the metal to a given curve. Depending on the profile and the radius, a pyramid roller may also be used.”
This project used radiused 1/8-inch metal plate panels. (Photo courtesy of Americlad)

(Photo courtesy of Americlad)
According to Kweton, “Single-skin metal panels oftentimes will conform to the curve without much additional manipulation; think smaller flat-lock tiles on a very gentle radius. Metal composite material (MCM) can indeed be curved. Each manufacturer has fabrication instructions that indicate what the minimum radius is that can be achieved and suggestions on how to do so. This is very commonly seen on MCM column covers.”
“MCM can be curved for a wall panel application but dependent on the profile, relief cuts in the legs may be possible, but more often than not, the profile may require a combination of adhering angles with a structural sealant to the back side to bring two parts together,” says Mike Wallace, president ofAmericlad LLC, Rogers, Minn. “The 0.25-inch aluminum plate panel is a great alternative for radiused work. The profile can be produced in the various flat and radiused parts, and welded and ground smooth to give a cast appearance. Traditionally, these parts can be post painted where the panel will be near perfect. When the polyethylene (PE) core was still commonly used, one could actually plastic weld the parts together to achieve the profile; however, as fire-resistant core used most of the time now, the parts cannot be plastic welded. Additionally, the fabricator has to take great care in bringing the two 0.02-inch face sheets together as you have the mill finish edge and attempting to bring two very thin sheets together where it looks uniform. Typically a radiused wall panel can be installed no different than a flat wall panel. Obviously proper clip spacing should be considered.”

This church’s appearance benefitted from curved metal panels. (Photo courtesy of Drexel Metals, a Carlisle company)

(Photo courtesy of Drexel Metals, a Carlisle company)
Curved Metal Roofs
Curved metal roofs were more commonly seen on commercial buildings, but are now gaining popularity in residential projects. Providing dramatic visual appeal, a curved metal roof—also known as a radius roof—can highlight any architectural design. Forming multiple-radius curves eliminates seam lines and provides a smooth line for the eye to follow.
Curved roofs are built out of structural steel, light-gauge framing, metal and wood substrates depending on the application and it being convex or concave or in some cases a serpentine or ogee type curve,” McLauchlan says. “The level of radius is going to be dictated by the material—steel, aluminum, copper, zinc—and panel configuration.”
“For standing seam panels, we have specialized machinery, referred to as a SCHLEBACH RBM25.38 that can curve 1-inch and 1.5-inch seam height standing seam panels in a convex curve, as well as an attachment to produce concave curves for the same panels,” Kweton says.
QUADRO 25X40 Cladding Wall Panel Forming Machine
Curving Success
Wallace explains, “The biggest error for curved wall panels would be not getting accurate field measurements and information relative to the radius. The fabricator will typically build it to the information given, but if anything is off on the field measurements it could become problematic as field repairs on the panel itself can prove to be difficult. Ideally, areas like this should be laser scanned for the best accuracy.”
Curved metal panels can modernize and transform the look of any building. (Photo courtesy of Sheet Metal Supply)
Kweton stresses starting with “a very exact template for the project, especially if it is being formed in a shop and subsequently shipped to the job site. Rushing the job and forcing anything into place at the risk of deformation would be myopic.”
McLauchlan says the process needs to be planned out, and that all must understand the process to achieve the radius. “At minimum you should plan for three to five additional panels per roof deck to allow for damage in handling and installation.” He cites common mistakes and errors made when curving metal panels are:
• Not checking or knowing how to measure your radius
• Not running test panels to check measurements and overall fit
• Not checking the substrate for uniformity across the entire roof surface
• Not being familiar with the curving equipment and its use
• Panel not being run to specifications and not functioning with the curver due to conformity issues
• Installation errors with over driving attachment creating a pinch point in the panel system
Don Benedict, Mid-Atlantic sales manager atDrexel Metals, Levittown, Pa., says, “The technician curving the panels on-site must have an attentive supporting cast when curving panels over 20 feet. The persons feeding the panel in and transitioning to taking the panel out are as important as the person running the radius machine. If the panel is held too high or too low, it can cause the panel not form correctly and cause loss material.” Furthermore, he advises:
• When running long length panels, a shorter version (10 to 20 feet) should be set on the deck at multiple points to ensure its radius conformity to the deck.
• Panels can be slightly under curved and still work. The ends that are slightly off the deck on the ends can be sucked down without distorting the panel.
• Panels that are over curved are a loss. When the center is high due to over curving and is pushed down, you are essentially trying to un-curve the panel and buckling will occur causing a loss. Cutting shorter panels out of it is the only viable option depending how bad the over curving is.
• Clip relief, beads, ribs or striations should not have any effect on the ability to radius a panel.
