What design wind speed should be used to design a tornado or hurricane safe room?
The design wind speed for a FEMA safe room is based on the risk of extreme wind events occurring at a given location. In 2008, FEMA and the International Code Council (ICC) jointly published new wind hazard maps that incorporate both historical events and the probabilistic occurrence of tornadoes and hurricanes. The safe room design wind speed maps for tornadoes and hurricanes are presented in Figures 3-1 and 3-2, respectively, in FEMA 361, Design and Construction Guidance for Community Safe Rooms (Second Edition, 2008, http://www.fema.gov/library/viewRecord.do?id=1657). Each map identifies wind speed regions, and the proposed safe room location must be identified on the map to find the appropriate design wind speed. For the tornado hazard, the safe room design wind speed is based on its location in one of four regions (Figure 3-1 of FEMA 361). For the hurricane hazard, the safe room design wind speed is based on its location in relation to wind speed “contours” (Figure 3-2 of FEMA 361
