Galvalume-coated Metal Roofs Will Last at Least 60 Years with Minimal Component Repair

The term “infrastructure sustainability” continues to gain importance because of rapidly increasing building infrastructure components around the country needing major repairs and/ or replacements. Consequently, roof maintenance or replacement materials and methods must last at least 60 years; consider LEED v4 from the Washington, D.C.-based U.S. Green Building Council. For more than 30 years, millions of square feet of Galvalume-coated roofs have resisted the atmospheric conditions to which they are exposed with little or no maintenance and are well prepared to continue protecting building interiors for more than 30 additional years. Material science and professional project engineering and installation prove Galvalume-coated metal standing-seam roofs will perform for that period of time.

This is a nine-year-old painted Galvalume roof in Alabama.

This is a nine-year-old painted Galvalume roof in Alabama.

MATERIAL SCIENCE

The first standing-seam metal roof was introduced by Armco Steel Corp., Middletown, Ohio, at the 1932 World’s Fair in Chicago. Armco Steel ceased doing business many years ago, but its standing-seam metal roof design has been adopted by all manufacturers in today’s commercial metal roofing market. The second longest-lasting introduction into this market was in the early 1970s when Bethlehem, Pa.-based Bethlehem Steel introduced a Zinc/Aluminum coating—now known as Galvalume—for carbon-steel metal roofs. This coating, applied to both sides of the steel coil, has been successfully used for the majority of metal standing-seam roofs ever since.

Since Galvalume was introduced, there have been several evaluations, reports and predictions as to how this product would “weather” the test of time. In 2012, the Chicago-based Metal Construction Association (MCA) and Olympia, Wash.-based Zinc Aluminum Coaters Association (ZAC) commissioned a study to perform forensic tests at 14 existing Galvalume standing-seam metal roof sites throughout the country in varying climates and precipitation pH. The average age of these roofs was more than 30 years at the time of testing.

Initially, the sites were selected based on temperature and humidity zones throughout the U.S. As the field results were processed, however, it became apparent the expected lives of these roofs were directly dependent on the precipitation pH levels with very little correlation to temperature and humidity. The building sites chosen were located in the following states:

  • Massachusetts (2 sites)
    This Galvalume roof in Missouri is nine years old.

    This Galvalume roof in Missouri is nine-years old.


    Ohio (3 sites)
    South Carolina (2 sites)
    Georgia (1 site)
    Colorado (1 site)
    New Mexico (1 site)
    Arizona (1 site)
    Oregon (1 site)
    Wyoming (2 sites)

The study was directed by MCA and three independent consultants and their firms, which managed and performed the field work: Rob Haddock of Metal Roof Advisory Group, Colorado Springs, Colo.; Ron Dutton of Ron Dutton Consulting Services LLC, Annapolis, Md.; and me and my firm Metal Roof Consultants Inc., Cary, N.C. This group, plus Scott Kriner, MCA’s technical director, authored the actual report, which was issued by MCA and ZAC in November 2014 and is available online.

The team harvested and analyzed actual field samples of Galvalume-coated metal standing-seam roof panel materials and sealants and examined all the individual roofs’ ancillary components. Finally, it created an experienced assessment of the roofs’ conditions and associated costs to replace.

PHOTOS: METAL ROOF CONSULTANTS INC.

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About Chuck Howard, P.E.

Chuck Howard, P.E., is owner of Metal Roof Consultants Inc., Cary, N.C., where he provides commercial metal roof consulting and engineering.

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