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Every spring and throughout the summer, much of the U.S. is subjected to thunderstorms that produce damaging hail. Property damage can manifest in several forms: broken windows, damaged roof top equipment, and roof damage. With a residential roof replacement starting at several thousand dollars and a commercial roof at tens of thousands, functional roof damage is probably the largest expense exposure for most buildings.

When a roof is no longer performing its intended function, the mechanism that brought it to that condition must be determined for the purposes of identifying coverage. What is the intended function of a roof? The main and most obvious one is to keep weather-related elements out of the building. There also are energy-related, service life, and structural aspects to a roof. When one of these functions is affected, the cause of that damage must be determined. This could include storm-related damage, maintenance issues, construction or manufacturing-related defects, and mechanical damage. Mechanical damage can be broken into two subcategories: intentional and unintentional.

When hail strikes a property, it indiscriminately hits whatever is in its path. Hail can fall straight down or can be directional if pushed by wind. In either case, it will not decide to hit the roof but avoid the fence, air conditioning equipment, satellite equipment, or the SUV parked out front (unless, of course, they are shaded by slopes of the roof or the building due to the directionality of the hail). Armed with this preliminary information, an engineer can start to devise a layered approach to an investigation to determine if the functional damage noted on the roof system is storm-related or from some other mechanism. The layers of this qualitative approach include the following.

Distribution - Hail damage would be expected to be random in size and distributed throughout the property (be mindful that it can have a directional component to it due to wind). On a sloped roof, hail can damage all slopes or just the windward slopes. An indication that the damage is not hail-related would be when damage is noted on some (but not all) windward slopes and some leeward slopes. Otherwise, hail related damage would be random in nature causing damage not only to the roof system, but also other exposed elements.

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David P. Amori, PE, RRC, Vice President of Engineering at EFI Global, is a Structural / Geotechnical Engineer and Registered Roof Consultant with more than 22 years of domestic and international experience in building and heavy civil construction and engineering. His responsibilities include the oversight of the engineering service line, product delivery, quality, training and mentoring, business development, and executive team liaison.

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