47.5 MB - The Whole Building Design Guide

Existing Facilities without Tornado SheltersWhere the number of recorded F3, F4, and F5 tornadoes per3,700 square miles is one or greater (see Figure 3-2 and discussionof Fujita Scale in Section 3.1.1), the best available refuge areasshould be identified if the facility does not have a tornado shelter.FEMA 431, Tornado Protection, Selecting Refuge Areas in Buildingsprovides useful information for building owners, architects, andengineers who perform evaluations of existing facilities.To minimize casualties in critical facilities, it is very important thatthe best available refuge areas be identified by a qualified architector engineer. 14 Once identified, those areas need to be clearlymarked so that occupants can reach the refuge areas withoutdelay. Building occupants should not wait for the arrival of a tornadoto try to find the best available refuge area in a particularfacility; by that time, it will be too late. If refuge areas have notbeen identified beforehand, occupants will take cover whereverthey can, frequently in very dangerous places. Corridors, as shownin Figure 3-104, sometimes provide protection, but they can alsobe death traps.Figure 3-104:View of school corridorafter passage of a violenttornado (Oklahoma,1999)14. It should be understood that the occupants of a “best available refuge area” are still vulnerable to death and injury if the refuge area was notspecifically designed as a tornado shelter.3-130 MAKING CRITICAL FACILITIES SAFE FROM High Wind