The Federal Emergency Management Agency (FEMA) has its own guidelines for residential and community storm shelters, which they refer to as “safe rooms” in FEMA 320 and FEMA 361.4
Both ICC 500 and FEMA offer criteria for a structure’s ability to withstand wind loads, rain loads, hydrostatic loads, pressure differentials, and wind-borne debris loads.
Regions of the U.S. that fall within the 402 km/h (250 mph) wind-speed zone for tornadoes are required to have ICC 500-compliant storm shelters with the following building types:5
- K-12 schools
- Daycare facilities
- Emergency operation centers
- Fire, rescue, and ambulance stations
- Police stations
- 911 call centers
- Military installations
It is important to note how the design criteria for tornado and hurricane shelters differs due to the varying wind pressure, speed, and duration of the storms. Other factors impact the execution of these codes based on the structure’s occupant density, water supply, ventilation, and access to emergency power.
How do ICFs fit into resilient design?
While resilient design is broad and can be executed in numerous ways, new construction projects can easily apply these principles with the use of ICFs.
Once cured, the monolithic concrete wall is almost impenetrable, and the rigid insulation offers superior thermal protection of R-24, continuous and soundproofing of sound transmission class (STC) 50 plus, with concrete cores of 152.4 mm (6 in.) and greater. While an ICF core can be as narrow as 101 mm (4 in.), forms used specifically for disaster resilience are usually 203 to 304 mm (8 to 12 in.) wide. Further, an ICF wall thickness of 152.4 mm (6 in.) and greater core provide four-hour fire Underwriters Laboratories (UL) Listing–U930.
