Testing and certification for storm shelters and safe rooms
Two of the most destructive events nature delivers, tornadoes and hurricanes, pose a significant threat to life safety. Hurricanes generate wind speeds from 74 miles per hour (mph) to over 150 mph, while tornadoes generate wind speeds from 65 mph to over 250 mph. The damage that can result from exposure to these wind speeds has been established using the Saffir-Simpson Hurricane Wind Scale and the Enhanced Fujita Tornado Scale.
To protect occupants from these extreme wind events, including wind-borne debris impact, the International Building Code (IBC), International Existing Building Code (IEBC) and the International Residential Code (IRC) reference ANSI/ICC 500, the ICC/NSSA Standard for the Design and Construction of Storm Shelters.Storm shelters and safe rooms are hardened building structures designed specifically for the protection of occupants against injury or death from the threats of extreme weather events, including hurricanes and tornadoes. According to FEMA, when shelters and safe rooms are properly designed, constructed and evaluated for compliance with applicable requirements, occupants in these structures during extreme weather events have a very high probability of being protected from injury or death.
Code and FEMA requirements for ICC 500
ICC/NSSA 500,is a consensus-based standard that has emerged as the primary standard for the design, construction, and testing for safe rooms and storm shelters. The following are some of the codes and federal requirements that reference ICC 500:
- Section 423 of the International Building Code requires storm shelters to be provided for critical emergency operations and certain Group E occupancies when they are located in areas where the design wind speed for tornadoes is 250 mph. These facilities include 911 emergency call stations, emergency operation centers, and fire, rescue, ambulance and police stations as well as educational occupancies through grade 12 with occupant loads of 50 or greater.
The International Residential Code, Section R307,requires storm shelters, when provided, be constructed and evaluated in accordance with ICC 500. Additionally, FEMA P-361, “Safe Rooms for Tornadoes and Hurricanes: Guidance for Community and Residential Safe Rooms,” and FEMA P-320, “Taking Shelter from the Storm: Building a Safe Room for Your Home or Small Business,” reference ICC 500.
Understanding ICC 500 storm shelter certification standards
Among other things, ICC 500 includes impact and pressure performance criteria. One of the most critical parts of a storm shelter design is protecting the openings within the structure, such as doors for entry and egress and windows/shutters. These openings are to be designed, manufactured, tested and labeled to withstand tornado wind speed pressures, including wind-borne debris impacts. Door assemblies typically include the door leaf, a vision panel (if applicable), door frame and attachment methods, and opening and closing hardware, all of which are tested as an integral system using the same materials and construction as that proposed for actual use. Installation of the door assembly into the rough opening is just as critical as the manufactured door assembly itself. Storm shelter door assemblies must go through test protocol including impact and pressure testing.
- Impacts tests are delivered with up to a 15-pound 2×4 lumber missile traveling up to 100 mph.
- Pressure tests include static and cyclic pressure exposures, with the applied pressures dependent on the design pressure of the door.
- The ICC 500 conditions of acceptance for tornado shelters demonstrate that the door provides protection for occupants against extreme wind pressure, as well as wind-borne debris. The test acceptance is based on the assembly demonstrating the ability to maintain the applied loads, as well as other compliance criteria, to show that any breaches are within acceptable limits . Specific impact testing compliance criteria includes no perforation of the interior surface, no failure of load-bearing fasteners, no excessive spall of the test specimen and no permanent deformation exceeding 3 inches. Specific pressure testing compliance criteria includes sustaining the applied loads with no permanent deformation exceeding 3 inches.
Certification and labeling process for storm shelter components
FEMA does not test, approve or certify products, but the agency does require that manufacturers certify their products in accordance with ICC 500. Certification is evident by the application of a label to the manufacturers’ product indicating compliance with the standard. ICC 500 indicates that all impact-protective systems used for openings be labeled to indicate compliance. It is important that testing be conducted by an accredited testing laboratory such as UL Solutions laboratories, according to the requirements of the standard, and the test report must contain the information necessary for the code authority to determine code compliance.
UL certified windstorm-rated assemblies and products can be accessed using the UL Product iQ® online search tool. The ICC 500 certifications are located within the category “Products for Use in Windstorm Rated Assemblies (ZHLL).”
Products certified for use in windstorm rated assemblies are labeled with a UL certification Mark or UL Classified Mark that includes the product category (such as “Swinging Door for Use in Windstorm-rated Assembly”), the standards for which compliance was determined and details on test pressure and 2×4 missile impact speed, as applicable.