By Scott Balot, RRO, Senior Construction Consultant
& Jonathan Goode, Ph.D., P.E., Principal Engineer, Associate VP of Engineering
Basic forensic techniques when inspecting for hail-related damages to roof surfaces typically include the method of performing a “test square.” This method was developed by Haag engineers in the 1960s and is a widely accepted practice to this day and industry standard. (For more information on the history and methodology, see Richard Herzog’s blog post from April 2019.
The test square works well for hail due to the randomness of hailfall. Excluding areas that are covered or blocked by obstructions, any one area on the roof has a similar chance of being struck by hail that any other area has on the same roof. Certainly, there are other variables to hailfall including wind-driven directionality in which hail typically falls and the test square methodology captures this given that test squares are performed on each directional facing slope.
So, what about quantifying wind-related damages in the same manner? In order to answer that, it is important to understand the two basic types of wind damage that can occur to a roof system.