The Federal Emergency Management Agency does not approve, certify, endorse or recommend storm shelters or construction contractors, but FEMA recommends that storm shelter design and construction provide near-absolute protection from three-second gusts of a wind blowing at 250 miles per hour. Shelters should offer protection from flying debris. Such protection methods include shutters and polycarbonate glazing or laminated glass that resists impact. Shelter entry doors can swing inward or outward, but doors, roof decks and walls must resist windblown debris.
Storm shelter criteria vary and offer shelter occupants different protection levels. Shelter designs depend on wind pressure criteria from a variety of codes, guides and standards. The design wind speed and design wind pressure are interrelated. Shelters designed with doors that swing out provide more space within the shelter, while debris is less likely to obstruct doors that swing inward.
FEMA P-320 and FEMA P-361 list criteria for storm shelters and safe rooms. Structures should meet guidelines of design and construction stated in FEMA P-320, Taking Shelter from the Storm: Building a Safe Room for Your Home or Small Business, and FEMA P-361, Safe Rooms for Tornadoes and Hurricanes: Guidance for Community and Residential Safe Rooms. When purchasing storm shelters that manufacturers or contractors claim comply with criteria under FEMA P-320 or FEMA P-361, obtain independent engineering analysis or testing to verify the claims. Some states have individual certification programs, but there is no federal certification.