By Lori Greene
Due to the increased frequency and severity of windstorms across a large portion of the United States, requirements for storm shelters have been added to the International Building Code (IBC). Prior to the adoption of the 2015 edition of the IBC, the decision to mandate storm shelters was left up to states and local jurisdictions. However, the last four editions of the IBC have included prescriptive requirements for storm shelters, referencing ICC 500 – Standard for the Design and Construction of Storm Shelters.
A storm shelter is to provide a safe location for building occupants and community members during a hurricane or tornado. The IBC defines a storm shelter as: “A building, structure or portions thereof, constructed in accordance with ICC 500 and designated for use during hurricanes, tornadoes or other severe windstorms.” Two types of shelters are included in the IBC definition — residential storm shelters and community storm shelters. A residential storm shelter serves occupants of dwelling units and has a maximum occupant load of 16 people. A community storm shelter is a shelter that is not a residential shelter; it would serve a larger occupant load and/or serve occupants of other types of buildings.
Where Are Storm Shelters Required?
The IBC requirements for storm shelters apply to the portion of the U.S. where the shelter design wind speed for tornadoes is 250 mph. Based on the map of Design Wind Speeds for Tornadoes in ICC 500, this area covers all or a portion of 23 states ranging from Minnesota to Louisiana and from Texas to the western end of the state of New York. In these states, the IBC currently requires storm shelters in two types of buildings:
- Critical emergency operations such as 911 call stations, emergency operation centers, and fire, rescue, ambulance, and police stations.
- Group E educational occupancies (schools) with a calculated occupant load of 50 people or more, with the exception of Group E day care facilities and Group E occupancies that are accessory to places of religious worship.
Refer to the adopted codes for additional requirements related to the occupant load and location of these shelters.
ICC 500 Storm Shelter Requirements
When required by ICC 500, door assemblies must be tested and the approval must be listed with a third-party agency; door assemblies must then be labeled as complying with the performance requirements of ICC 500. The tests for vertical surfaces include multiple impacts of a 15-pound sawn lumber two by four propelled at 100 mph, which impact the door assembly in critical locations. These tests help to ensure that the door will remain closed and latched to protect the opening during a windstorm.
ICC 500 includes additional mandates for storm shelter doors. For example, the hardware used to latch the door assemblies protecting openings in the shelter envelope must be permanently mounted on the assembly and must require no tools to be engaged in the latched position. The latch(es) must automatically engage when the door is closed (and be incapable of being disabled), or the latches must be capable of being engaged by a building occupant. Once the latching mechanism is engaged, operating hardware on the non-egress side of the door must be locked, disabled, or inactive, so that it is not susceptible to being unintentionally unlatched by debris impact. ICC 500 also includes requirements for the instructional signage related to these openings.
Egress, Fire Protection, And Accessibility
In addition to the criteria listed in ICC 500, doors serving storm shelters must comply with several different codes and standards, including requirements related to egress, fire protection, and accessibility. For example, egress doors serving residential and community storm shelters must have hardware that is operable for egress without the use of a key or special knowledge or effort. Releasing hardware must not require tight grasping, pinching, or twisting of the wrist to operate, and must be mounted between 34 inches and 48 inches above the floor.
When storm shelter doors serve an assembly or educational occupancy with an occupant load of 50 people or more, the latching hardware must be panic hardware meeting all applicable requirements. The actuating portion of the hardware must measure at least half the width of the door, and the devices must be listed as panic hardware or fire exit hardware. Door swing is based on the normal occupancy of the space — doors serving an occupant load of 50 people or more must swing in the direction of egress.
Shelters must have an accessible route that complies with ICC A117.1, Accessible and Usable Buildings and Facilities, and doors serving community storm shelters are also required to comply with the ADA Standards for Accessible Design. Compliance with these standards helps to ensure that the doors can be used by all building occupants.
It can be difficult to sort through the layered requirements of the IBC, ICC 500, NFPA 80, the accessibility standards, and the applicable state and local codes, to ensure that door assemblies protecting openings in the shelter envelope meet the necessary criteria.
The accessibility standards mandate doors which meet the required clear opening size of 32 inches measured from the face of the door in the 90-degree position to the stop on the frame, with a minimum opening height of 80 inches, nominal. The opening force for interior, non-fire-rated doors is limited to five pounds, with most exterior doors and fire doors limited to 30 pounds to set the door in motion and 15 pounds to open the door fully. Closing speed must be a minimum of five seconds for the door to move from the 90-degree to 12-degree position. Thresholds are limited to a maximum height of a half-inch and must meet the slope requirements of the standard. If storm shelter doors are equipped with vision lights, the bottom of at least one light must be located no more than 43 inches above the floor.
For fire barriers and horizontal assemblies that separate community storm shelters from other building areas, ICC 500 requires partitions with a fire-resistance rating of two hours, and opening protectives (fire door assemblies) rated for 90 minutes. These assemblies must comply with most of the requirements of NFPA 80, Standard for Fire Doors and Other Opening Protectives, with positive-latching hardware, the appropriate hinges, gasketing, and other listed/labeled components. Vision lights, often specified in these locations for light transmission and visibility, must have glazing that is certified to provide fire protection and to withstand the testing requirements of ICC 500. An exception to the NFPA 80 requirements is that if fire doors and shutters are located in fire barriers that are only required for compliance with Section 603 of ICC 500, the doors are not required to be self-closing or automatic-closing.
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It can be difficult to sort through the layered requirements of the IBC, ICC 500, NFPA 80, the accessibility standards, and the applicable state and local codes, to ensure that door assemblies protecting openings in the shelter envelope meet the necessary criteria. It’s also important to note that states and local jurisdictions often modify the model codes, which can result in a reduction or an expansion of these requirements. In some cases, states have removed the requirements for storm shelters from the adopted codes, and in other jurisdictions, storm shelters may be required by local regulations even if they are not required by the IBC.
A door hardware consultant who is familiar with all aspects of these codes and standards can assist with the specification and selection of appropriate doors and hardware. For questions on the adopted codes and referenced standards, the Authority Having Jurisdiction (AHJ) should be consulted for guidance.
Lori Greene, DAHC/CDC, FDAI, FDHI is the manager, codes and resources for Allegion. She has worked in the door and hardware industry for more than 35 years and is responsible for support and training on the code requirements related to door openings. She participates in the code development process with the Builders Hardware Manufacturers Association (BHMA), and shares daily updates on iDigHardware.com.
