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Can Hail Damage a Ballasted Roof System

Project Success Description

After a 2011 hailstorm in Carter Lake, Iowa, employees of the local La Quinta Inn noticed a leak in the roof of their hotel. The building owner submitted an insurance claim, stating the 10-year-old roof needed to be replaced due to hail damage. The insurance company then turned to John Thomazin of REDI Engineering Inc. to complete a roof inspection.

John began by conducting a visual, non-destructive inspection. The hotel roof system consisted of an ethylene propylene diene monomer (EPDM) rubber membrane, covered by a ballast of smooth river rock. The ballast absorbs the energy of hailstones when they strike the roof, which reduces the amount of impact on the EPDM membrane. Damage to a solidly structured, ballasted, EPDM roof system can occur with hailstones, but not unless they are at least 2.5 inches in diameter.

The insurance claims manager attended the inspection to discuss the roof system composition, function, flaws and common failure mechanisms. Interviews with the property manager and maintenance staff revealed that the hotel had been dealing with leaks before the hailstorm blew through. The ceilings and walls in three guest rooms on the top floor had several new coats of paint due to the water damage.

During the storm, hail stones had accumulated in the roof drains, which prevented proper drainage. The rainwater and melting ice gathered on the roof, found their way into existing damaged seams of the EPDM membrane, and seeped down into the interior of the hotel. Contrary to the building owner’s assumption, the hail did not create the roof leak, but caused more water to flow through the already damaged roof system.

Within 10 working days, REDI Engineering had completed both the site inspection and a written report. The report described the building components and details of the obstacles encountered during the inspection. Also included were an opinion of what caused the roof leak and recommendations for repairs. An appendix offered additional information regarding the hail size and hail damage threshold for different roofing materials.

The building did not need a new roof. Less expensive repair and maintenance options were available. REDI advised the building owner to do an infrared scan of the roof to reveal damaged areas. Wet and dry materials release different amounts of heat, which means the scan can detect areas with excessive moisture. In addition, repairing the damaged seams in the roof membrane would help prevent the need for future repairs. The building owner could extend the life of the hotel roof by scheduling recurring inspections and repairing small problems as they occur.

As a result of the inspection, the insurance company gained a deeper understanding of the roof system structure and was able to better assess the situation. The building owner learned that minor roof repair and maintenance were possible, in this case, as affordable alternatives to total roof replacement. After reviewing REDI Engineering’s written report, the insurance company was able to resolve the insurance claim.

John Thomazin MSME, P.E.

John Thomazin MSME, P.E.

Building-Inspection Engineer

Since 2006, John has provided expert opinions to help resolve insurance claims related to construction defects and storm damage. Using deep knowledge of all aspects of a building’s thermal and moisture protection, and experience with roofing systems of all types, John helps business owners understand and implement best practices for maintenance and leak detection. He also writes repair specifications for defects and assists in the preparation of construction documents and construction-document administration. John holds a Bachelor of Science degree in Mathematics and a Master of Science degree in Mechanical Engineering. He is a licensed Professional Engineer in the State of Nebraska and has been a member of the National Academy of Building Inspection Engineers since 2007.