Outside the Box

Oct. 30, 2003
Plastics Can Help Green Up the Exterior
Across the country, commercial builders are striving to create green buildings. One of the materials making a real contribution in reducing the environmental footprint of many of them is plastic.In many cases, the insulating properties, durability, and aesthetics of plastic make these products a commonsense choice for commercial building exteriors. They can help reduce building energy consumption, reduce or eliminate the need for harsh cleaning compounds and paints, and provide unique aesthetic appeal over the life of the building.Both spray polyurethane foams (SPFs) and exterior insulation and finish systems (EIFS) can help contribute to superior energy efficiency while creating façades with character and beauty. SPFs can be applied – usually as one-step, two-component, sprayed-in-place rigid foam – over structural supports of virtually any size and geometry.These products can give a building owner nearly unparalleled creative freedom. They can also help keep construction methods straightforward, even as they help to produce a façade that is lightweight and easy to finish with a durable cladding. EIFS, whether applied over a complicated 3-D shape created with SPF or over a more traditional rectangular flat structure, typically consist of the following components:Insulation board, made of polystyrene or polyisocyanurate foam, secured to the exterior wall surface with a specially formulated adhesive and/or mechanical attachment.A water-resistant base coat applied on top of the insulation and reinforced with fiberglass mesh for added strength.A durable finish coat – typically using acrylic copolymer technology – which is both colorfast and crack-resistant.SPFs and EIFS, applied properly to the exterior of the structure, can act as an effective air barrier, reducing air infiltration substantially. They can also increase total R-value across the walls, improving occupant comfort and reducing building energy consumption, which may, in some cases, allow the specification of smaller-capacity HVAC systems. Lower energy consumption can provide environmental benefits over the life of the building.EIFS exteriors can resemble stucco or stone, and provide a wide latitude of finishing options. They can be specified in virtually limitless colors and a wide variety of textures, and can be fashioned into nearly any shape or design – most of which is computer-generated – for detailing.Moreover, EIFS rarely need painting. Most EIFS exteriors are specially formulated with a 100-percent acrylic binder, which provides superior resistance to fading, chalking, and yellowing, so the systems tend to maintain their original appearance over time. Since the color is integral to the finish coat, the same color appears beneath an abrasion. The finish coat also exhibits excellent resistance to dirt, mildew, and mold.Plastics-based façades are also dimensionally flexible, which contributes to their longevity. When walls expand or contract with changing temperatures, plastics-based exteriors can be resilient enough to “absorb” building movement and avoid the unsightly cracking problems that can be common with less flexible exteriors.Overall, plastics may represent one of the best combinations of environmental footprint, aesthetics, longevity, and ease of construction for commercial building exteriors.Mike Levy is executive director of the polystyrene packaging council and expandable polystyrene supplier council at the American Plastics Council Inc. (www.americanplasticscouncil.org), headquartered in Arlington, VA.

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