Silicone Seal has Better Mettle in Curtain Wall

Replacement in architectural application improves installation and protection

You put in the glass, drive in the silicone gasket, and you are pretty much done," says Brad Wells, the design engineer behind EFCO Corporation’s new 5800 E-Wall curtain-wall system. Based in Monett, MO, EFCO is a manufacturer of commercial glazing and framing systems including windows, doors, storefronts, entranceways, and curtain-wall systems. The company offers both traditional pressure-glazed aluminum curtain-wall systems, which uses a metal pressure plate and cover on the exterior, as well as the new E-Wall system that employs a silicone gasket, manufactured by Lauren Manufacturing, New Philadelphia, OH, at the exterior.

Traditional pressure-glazed curtain wall systems have several internal areas that require sealant, along with a pressure plate on the exterior that must be screwed in place before a face cap is installed, to give the finished appearance. Since the new E-Wall system requires no internal sealants, assembly time is much faster. Once the glass is set in place, a single strip of made-to-fit silicone gasket is driven into the framing around each of the glass units.

Designing the E-Wall is one thing, but making it is another. Explains Chuck Laney, Lauren Manufacturing’s director of engineering and quality, "The problem was that the tooling required to support any kind of design change was immense." Laney notes that, previously, EFCO injection molded the corners of the frames. However, this method raised tooling costs every time the engineering department modified the design of the curtain wall corner to meet architectural requests for different frame sizes and angles. "The first attempt for the E-Wall," says Laney, "used a straight cut with a much larger molded corner. It was very noticeable."

Lauren changed the gasket design by miter cutting the end of the frame before splicing it. "Our product was more difficult to manufacture, but looked more continuous," says Laney. "The molded section looks almost like an accent, not a molded splice. Once they found that we could produce the more complicated part at a competitive price, they were hooked."

Wells comments that, in addition to less installation time and a more aesthetically pleasing appearance, the new gasket also provides superior thermal and water/wind resistance properties compared to traditional pressure plate systems. Silicone transfers the flow of heat to the outside of the building much more slowly than aluminum. And Laney points out that, by providing a smaller temperature gradient, a silicone seal also resists condensation better than metal, and its condensation resistance factor (CRF) is higher than metal. "The condensate is ugly, messy, reduces the life of the window system, and is even thought to be unhealthy," he says.

The E-Wall gasket helps seal out water and wind from outside the building. "We test water resistance to 15-lb/sq ft on pressure glazed systems," says Wells. "The E-Wall easily outperforms these systems." While silicone generally does not have a high tensile strength, much of its inherent tensile strength is retained at very high temperatures. When properly fabricated, it does not adversely affect materials into which it comes in contact. Silicone seals also dampen vibration, lowering sound levels transmitted to the inside of the building from the outside by 3 dB, as compared to metal elements.

EFCO estimates that using the silicone gaskets saves between 25 and 45% of curtain wall installation costs on a typical straight wall. They anticipate even more savings on curved wall structures. While the gasket does increase the cost of materials for the E-Wall system, the price increase is offset by the labor savings enabled by the gaskets.

The EFCO E-Wall Silicone Gasket System comes in 21 standard EFCO colors, but architects, contractors and engineers will specify custom shades. "We were able to supply all of their standard colors and produce several new ones in a short amount of time," says Laney. "We are testing colorfastness of our product and supplying warranty information as we can to help EFCO sell their system."

Lauren Manufacturing,
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