ICC-500 Storm Shelters

Posted on October 30, 2020 by Ryan Garden

Generally speaking, code changes require slightly modifying engineering procedures, policies, or methodology. One recent code change has not followed the “slight change” model. New schools, and some school additions based on their size, are required to incorporate an ICC-500 storm shelter into their construction. These shelters need to provide shelter for the students as well as faculty and staff so naturally the tendency is to locate the shelter in either the auditorium or the gymnasium. From a design standpoint, these are the absolute worst areas as they feature the tallest unsupported walls and the longest roof spans on the project.


The loads associated with the ICC shelter are extremely high. 250 mph design wind speeds lead to applied pressures/suctions that make you shake your head at least twice if not three times. The greatest difficulty from a precast standpoint is that everything we incorporate into a flexural member to increase the span works against us when we try to withstand the uplift loads associated with the tornadic event.  

Wells is in the process of developing two systems to handle the ICC requirements for spans up to 100’.  One system incorporates double tee roof members with applied topping and the other uses bridge girders paired with flat slabs and requires no additional field topping. Look for upcoming webinars that will cover these two options for your consideration.

Ryan Garden
VP, Chief Engineer