For architects as well as roofers, the standing seam panel has been the go-to system for metal roofing. It’s worked as a watertight system for decades; one panel, with a female leg, laps over the male leg of the already installed panel.
Have you considered a symmetrical panel metal roofing system? A symmetrical panel system features identical left and right seams joined with a mechanically seamed cap. Two beads of butyl sealant are factory applied to the seam cap, so when the cap is engaged to the metal panels, a watertight bond is created with no breaks or voids. This design offers benefits not afforded by a standing seam system with a male and female leg.
Installation versatility
A standing seam panel system is typically installed from left to right, covering the male leg with the female leg, and then moving on to the next panel in only one direction.
A symmetrical system can be installed in either direction, left to right or right to left. It can also be installed and joined with its mechanically seamed cap from the center out.
A symmetrical system offers competitive uplift performance when installed with standard clips. Some symmetrical panel manufacturers offer multi-span clips for the system that can offer as much as three times the uplift resistance as standard clips. Often, to optimize performance and value, standard and these multi-span clips are used on the same project … the multi-span clips are used on the corners and other strategic areas where wind forces are greater. Standard clips are used in areas not as greatly threatened by wind.
Replacement simplicity
The symmetrical system offers a potential cost-saving benefit to building owners. It offers easy single-panel removal and replacement. Panels can be re-installed which would require only the purchase and installation of new caps.
With a typical male-leg, female-leg standing seam roof, the removal of a panel would require the removal and replacement of several panels. That could lead to hours and hours of labor, not to mention the cost of replacement panels.
Retrofit possibilities
McElroy Metal developed a patent-pending Retrofit Clip for its 238T Symmetrical panel to allow for its installation in metal-over-metal retrofit projects. The 238T Retrofit Clip sits between the ribs of the existing roof, eliminating the need for expensive sub-framing, greatly reducing material and labor expense. The existing roof remains in place, so there is limited disturbance to building occupants.
The tall clip also stands above the seams of the existing panel, allowing space for insulation to assist building owners control utility costs.
Experienced metal roofing installers will have no trouble working with a symmetrical panel system. For the advantages stated here, they should prefer working with it.
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Ken Gieseke is vice president of marketing at McElroy Metal, with a Bachelor of Science in Marketing from Southern Illinois University, Carbondale, and an MBA from Louisiana State University in Schreveport. He currently serves as a board member for the National Frame Building Association and the Metal Roofing Alliance. For more information, visit www.mcelroymetal.com.