The 2020 edition of ICC 500 includes several updates. Dave Stammen, engineer for the built environment at UL LLC, provided an overview of those changes to the Fenestration & Glazing Industry Alliance (FGIA) in a webinar titled, “ICC 500-2020: Updates to the Tornado and Hurricane Storm Shelter Standard.”

Committee work began on the new edition back in September 2018. ICC 500-2020 was approved by ANSI on November 2, 2020 and it published in December 2020 for the 2021 I-codes. Stammen recommended that members purchase the edition with commentary. The ICC 500 Committee decided to keep the standard under continuous maintenance to allow for a 2023 update for adoption in the 2024 I-codes.

ICC 500 is referenced in the 2009-2021 International Building Code (IBC) and the International Residential Code. Section 423 of the IBC requires that storm shelters be constructed in accordance with ICC 500 when located in areas where the shelter is designed to a tornado windspeed of 250 mph or greater, for critical emergency operations such as 911 call stations, and Group E occupancies such as schools or daycares. The 2021 International Existing Building Code Section 303 has additions to Group E occupancies with greater than 50 occupants in 250 mph zones, which include school campuses, gymnasiums, theaters and community centers.

Stammen pointed out that storm shelters are developed around human survival, not building preservation, so when products are tested for use in storm shelters it’s not a requirement that the product still be able to operate after testing. He also reminded members that FEMA doesn’t approve or certify products for use in storm shelters.

ICC 500 Changes

There are nine chapters in the 2020 edition of ICC 500, which is the same number of chapters in past editions, though some of the titles may have changed. In Chapter 1, the most notable change is to the scope. It now specifies that the design of facilities for use as emergency shelters after the storm is outside the scope of this standard. In Section 108, it now states that owners must submit a written preparedness and emergency operations plan to the authority having jurisdiction (AHJ) prior to approval.

Section 112 now states that impact-protective systems shall be listed and labeled donating compliance with the standard. There are also new marking requirements such as the type of system, the hazard it’s designed for, the missile weight and speed tested to, the design wind pressure and the edition of ICC 500 to which the product is evaluated.

Section 113 is a new addition to the standard that pertains to evaluating, maintaining and repairing storm shelters and components. It requires that owners or agents visually evaluate the storm shelter annually or when requested by the AHJ. Maintenance and repairs must be done with the components specified with the tested/listed assembly.

In Chapter 3 Section 304, the hurricane shelter design windspeeds were altered. Section 305 now separates tornado and hurricane requirements rather than grouping them together. The missile criteria for tornadoes is still a 15-pound 2×4 and for hurricanes it’s still a 9-pound 2×4.

Stammen emphasized that Section 306.1 clarifies that only products tested to the 250 mph tornado windspeed requirements can meet hurricane requirements. He explained that while the missile is heavier for tornado testing, there could be cases where the high windspeeds from hurricanes would contribute more impact energy to the missile than calculated in the slower tornado windspeed zones.

Similarly, assembly alterations such as a change of glazing will require new evaluation or testing, even if the new component is stronger than the previous product. This is because the stronger component could push the impact energy to a weaker part of the assembly and cause it to fail.

Chapter 5 Section 507.3 specifies that operating hardware on the unprotected side can’t become disengaged due to the impact of debris. Flying debris or a missile impact could cause the hardware to unlatch and the product to open, leaving occupants at risk.

Chapter 6, which focuses on fire safety, has been modified so fire protection systems are not required to remain functional during the event (i.e. sprinklers) and fire doors and shutters in fire barriers are not required to be self or automatic closing.

There were no major changes to Chapter 8 Section 802, which focuses on test specimens. It allows for fire testing to be separate from pressure and impact testing. Impact-protective systems still require that the maximum and minimum size listed for use be tested, however, it clarifies that static testing must be done on the largest size listed for use. Clarifying language also was added, specifying static testing in both directions for impact-protective systems, unless the worst-case direction is evident.

Section 803 now allows for the missile lengths used for testing to be within a set range. For tornado testing, the missile can be between 10 and 15 feet as long as it’s 15 pounds. For hurricane, the missile can be between 6 and 10 feet as long as it’s 9 pounds. In addition, impact locations have been clarified to be within a 2.5-inch radius of the circle and the entire missile does not have to be within the target. Miami Dade requires that the entire missile strike within the circle.

For window assemblies and other glazed openings, the missile must impact the center of the smallest glazed opening and interface corner. There should be no more than two impacts on one specimen (without mutual consent). For interior mullions there should be additional impacts on the mullion and at the mullion base.

ASTM E330 is used for static testing and ASTM E1886 is used for cyclic pressure testing. Section 804 now clarifies the use of 9,000 cycles per Table 1 of ASTM E1886.