New research from the Metal Construction Association (MCA) (Chicago, Illinois) concludes that standing-seam steel roofs coated with a 55% Al-Zn alloy can last at least 60 years. The study, sponsored by MCA and the Zinc Aluminum Coaters Association, analyzed low-slope, unpainted 55% Al-Zn alloy-coated steel roofing at 14 building sites in five different climates in the United States: hot-dry, hot-humid, cold-dry, cold-humid, and moderate-acid. The study incorporates the results of multiple field inspections and independent laboratory analyses of metallic corrosion of the roof panels and all integral ancillary components that impact the end-of-roof service life. The roofs showed corrosion rates that project service lives well beyond that of most buildings. The range depended on the climate and pH of the local precipitation. The study also confirmed that these types of metal roofs resist corrosion in weak spots such as sheared edges and panel profile bends. The study acknowledges that all roof systems require a regular maintenance program (at least annually) to achieve the kind of service lives seen in this study. To learn more, visit metalconstruction.org.