Meteorological Investigation – Commercial Roof Failure
October 11, 2022
A section of the roofing system of a big box retail store collapsed during a thunderstorm event. The evidence collected during an inspection indicated that excessive water loading caused by rainfall may have contributed to the partial collapse. Rainfall data measured at a nearby airport located 3 miles away indicated that only a small amount of rain (approximately 0.25 inches) had occurred within 30 minutes of the reported time of collapse.
Rimkus was retained to determine the weather conditions leading up to the reported time of the roof collapse. During the course of our investigation, we collected and examined local rainfall data from multiple public and private sources in conjunction with site-specific radar data. Based on our investigation and analysis, we were able to formulate the following opinions:
- An isolated thunderstorm produced locally heavy rain over a short amount of time at the incident location.
- An examination of localized weather data indicated that 1.10 inches of rain had occurred at the incident location during the 20 minutes prior to the reported roof collapse.
- An examination of the radar data indicated that in addition to the heavy rain event, a downburst occurred within 0.5 miles of the incident location and produced downward-propagating wind forces during the time of the roof collapse.
- A review of in-store video showed evidence of severe downward vibration caused by vertical wind force.
- Excessive rainfall and the identification of a downburst wind event were determined to be contributing factors and likely cause of the roof collapse.