The Effects of Hail on Metal Roofing Systems

The Effects of Hail on Metal Roofing Systems Jim D. koontz, RRC, PE, and Troy L. white, PE Jim D. Koontz & Associates, Inc. 3120 north Grimes, Hobbs, nM 88240 Phone: 575-392-7676 • Fax: 575-392-7602 • E-mail: [email protected] and [email protected] 29th RCI InteRnatIonal ConventIon and tRade Show • MaRCh 20-25, 2014 koontz and whIte • Abstract The purpose of this study is to evaluate the effects of hail size on metal roofing and its ability to shed water over an extended period of time. Substantial indentation at side laps, end laps, or at the juncture with concealed clips can result in conditions that may affect water-shedding capabilities. Commonly used metal roof panels will be impacted by variably sized ice spheres at multiple locations across the panel per National Bureau of Standards 23. Panels will then be visually inspected and subjected to laboratory testing to determine effects on water-shedding capability and coating resilience and performance. Speakers Jim D. Koontz, RRC, PE – Jim D. Koontz & Associates, Inc. Jim Koontz, president of Jim D. Koontz & Associates, Inc., is a graduate of Tulane University with a bachelor of science degree in engineering and a master’s in business administration. Koontz has been involved in the roofing industry since 1960 and began test­ ing roofing material in 1976. he has experience as a roofer, estimator, consultant, lecturer, researcher, and expert witness. Koontz was first published in 1984 and has numerous articles relating to roofing material/product research to his credit. Troy L. White, PE – Jim D. Koontz & Associates, Inc. Troy White received a master’s degree in civil engineering from Texas Tech University in Lubbock in 2002 and became a registered professional engineer in Texas and New Mexico in 2005 and 2008, respectively. he has worked as a construction observer, designer, and project manager in civil and architectural firms since March 2000. White recently became an associate with Jim D. Koontz & Associates, Inc. and currently serves as a construction observer, field investigator, and research associate within the firm. his experience ranges from industrial and public works infrastructure to roofing systems design, construction observation, and damage and failure analysis. • koontz and whIte 29th RCI InteRnatIonal ConventIon and tRade Show • MaRCh 20-25, 2014 The Effects of Hail on Metal Roofing Systems ABSTRACT To evaluate the effect of hail impact on The purpose of this study is to evaluate various metal roofing systems, two methods the effect of hail on metal roofing. Metal of impacting metal roofs were utilized. Both roofing systems utilized on both steep- and ice and steel spheres were used to impact low-sloped roofs constitute a major market selected metal roofing systems. A pneumat­ share of the roofing industry. The function ic launcher was used to fire ice spheres at of metal roofs obviously can vary from a metal roofs. The ice spheres were propelled simple water-shedding capacity that pro­ at velocities listed by the National Bureau tects the building, to wind resistance, fire of Standards (NBS) Building Science Series resistance, aesthetics, and potentially some No. 23.2 The metal roofing systems were hail resistance. also impacted with steel spheres by meth­ Within a substantial area of the United ods listed by Underwriters Laboratories States, hail occurrence is common (refer to (UL)3 and by procedures listed in the mar­ the hail map1 in Figure 1). Dependent upon keting literature published by the metal geographical location, metal roofs are often roofing manufacturers. impacted by hail, resulting in permanent Some metal samples indented during indentations. Significant insurance claims naturally occurring hail events were also are filed as a result of these indentations, examined and impacted. Comparisons were with disputes arising as to whether the made of naturally occurring hail indenta­ indentations constitute actual physical loss tions and indentations that were a result of or damage. Substantial time and expense laboratory testing. Observations were made are expended to resolve these claims. The of differences between impacting a metal extent to which these indentations affect roof with steel spheres or with ice. the functional attributes of the metal roof system—including water-shedding capac­ InTRoDuCTIon ity, wind resistance, aesthetic value, mate­ Mankind has used various types of metal rial longevity, and corrosion resistance—is roofing for thousands of years. historically, a common issue in these claims debates. the first metals used included both lead In exceptionally rare cases, metal roofs and copper. In some cases, the roofs had impacted with very large hail may split a service life of over a century. The temple at the site of impact. Substantial indentations at side laps, end laps, or at the juncture with con­ cealed clips can result in conditions that may affect water-shedding capabilities of a metal roof. Minor indenta­ tions may have little to no effect on roof perfor­ mance over an extended period of time. Aesthetics of hail indentations to metals roofs also come into consideration when assessing reported dam­ age. Figure 1 – Hail climatology map.