Browse the full Resources Index
Farm buildings across the Midwest are covered in a wide range of metal panel products, and the differences between them affect how storm damage is evaluated and repaired far more than a casual look at a dented barn might suggest. Exposed fastener panels, sometimes called screw-down panels, attach directly through the panel face into the girts or purlins beneath, with a rubber washer under each screw head to seal the penetration. These are the most common and generally least expensive panel type on machine sheds and pole barns, and they are also the type most prone to fastener backout and washer degradation over time, independent of any single storm event.
Standing seam panels represent a different approach, using concealed clips that attach to the substrate without penetrating the panel face, with adjacent panels interlocking along a raised vertical seam. This system is more common on higher-end agricultural buildings, equestrian facilities, and newer commercial farm structures, and it generally performs differently in wind and hail events than exposed fastener panels because there are no exposed screws to back out and the seam itself provides some additional stiffness. When standing seam panels are damaged, matching the exact seam profile and clip spacing from the original manufacturer is often necessary for a proper repair, since these systems are engineered as complete assemblies rather than as generic interchangeable sheets.
Panel gauge, meaning the thickness of the steel, is a specification that matters more to storm damage evaluation than many people realize. A lighter gauge panel, common on lower-cost agricultural buildings, dents more readily under hail impact than a heavier gauge panel, and this is a legitimate engineering distinction rather than a matter of degree in how carefully someone inspects the roof. Oil canning, the visible waviness or rippling that can appear on the flat portions of a metal panel between ribs, is a related but separate phenomenon that can result from thermal expansion, minor substrate irregularities, or manufacturing tolerances, and it is not always evidence of storm damage even when it becomes more visually apparent after a hail event prompts a closer inspection.
Distinguishing genuine hail damage from oil canning, pre-existing panel waviness, or ordinary weathering is one of the more technical judgment calls in a farm building inspection. Hail typically produces discrete, roughly circular indentations with some consistency in size that corresponds to the hailstone diameter reported for the event, often accompanied by corresponding damage on soft metals nearby such as gutters, vents, or downspouts. Diffuse waviness across broad panel areas without discrete impact points points toward a different cause. Chalk testing, close-range photography, and comparing damage patterns across multiple elevations of the same building all help build a defensible record.
Color and finish matching present a further complication on older farm buildings, since panel manufacturers periodically discontinue specific colors or change their coating formulations, and a building re-sided twenty years ago may have panels that are simply no longer produced. In those situations, decisions about whether a partial re-side is acceptable or whether a full elevation or building needs to be redone for a uniform appearance become part of the scope discussion, informed by the specific product’s continued availability from the original or a comparable manufacturer.
This article is general education about how the appraisal process commonly works. It is not legal advice, and specific procedures can vary by state and policy.
Russ Lis is a working property insurance appraiser and umpire based in Minnesota, serving clients nationwide. Contact Appraisal Resolution.