Design and Construction Guidance for Community Safe Rooms FEMA 361, Second Edition/August 2008 Any opinions, findings, conclusions, or recommendations expressed in this publication do not necessarily reflect the views of FEMA. Additionally, neither FEMA nor any of its employees makes any warrantee, expressed or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, product, or process included in this publication. Users of information contained in this publication assume all liability arising from such use. PREFACE Federal Emergency Management Agency (FEMA) publications presenting design and construction guidance for both residential and community safe rooms have been available since 1998. Since that time, thousands of safe rooms have been built using FEMA’s Hazard Mitigation Assistance Program. A growing number of these safe rooms have already saved lives in actual events. There has not been a single reported failure of a safe room constructed to FEMA criteria. This Second Edition of FEMA 361 presents updated and refined design criteria for safe rooms when compared to the First Edition’s 2000 criteria. The changes to the design criteria are the result of post-disaster investigations into the performance of safe rooms and shelters after tornadoes and hurricanes. Further, the changes also consider the new consensus standard from the International Code Council® (ICC®) and the National Storm Shelter Association (NSSA) released in August 2008, the ICC/NSSA Standard for the Design and Construction of Storm Shelters (ICC-500). The criteria presented in this publication address how to design and construct a safe room that provides near-absolute protection for groups of individuals sent to a building or structure expecting it to be capable of providing them life-safety protection from wind, windborne debris, and flooding. FEMA continues to support the development of consensus codes and standards that provide minimum acceptable requirements for the design and construction of hazard-resistant buildings; and FEMA supported and participated in the development of the ICC-500. Although the ICC-500 took much of what was presented in the First Edition of this publication and updated and codified it through the consensus standard process, some design criteria remain different between the two documents. The technical differences related to wind design criteria for both tornado and hurricane hazards, the design missile criteria for hurricane safe rooms, peer review requirements for the safe room designs, and siting requirements with respect to flood hazards are presented at the beginning of Chapter 3 of this publication. FEMA has maintained different criteria than what is provided in the ICC-500 in the same way FEMA continues to provide best-practices and design guidance on all types of hazard resistance construction (from residential buildings to critical facilities). Should safe room designers, operators, and emergency managers implement the FEMA criteria in their projects, they can feel confident knowing that they used the best-available information to guide the design and construction of a safe room (public or private) that provides near-absolute protection from the deadly winds and debris associated with extreme-wind events. TABLE OF CONTENTS Preface 1 Introduction 1.1 Purpose 1.2 Safe Rooms vs. Shelters 1.3 Background 1.4 Organization of the Publication 2 Protection Objectives 2.1 What is a Safe Room? 2.2 Safe Room Design Process 2.3 Safe Room Costs 2.4 Benefit-Cost Analysis 3 Design Criteria for Tornado and Hurricane Safe Rooms 3.1 General Approach to the Design of Safe Rooms 3.2 Load Combinations 3.3 Tornado Community Safe Room Design Criteria 3.4 Hurricane Community Safe Room Design Criteria 3.5 Residential Safe Room Design Criteria 3.6 Flood Hazard Design Criteria for Safe Rooms 3.7 Product Testing 3.8 Permitting, Code Compliance, Professional Design Oversight, and Peer Review 3.9 Construction Documents, Signage Criteria, and Labeling 3.10 Quality Assurance/Quality Control and Special Inspections 4 Characteristics of Tornadoes and Hurricanes 4.1 General Wind Effects on Buildings 4.2 Wind-Induced Forces – Tornadoes and Hurricanes 4.3 Effects of Extreme-Wind Forces 4.4 Multi-Hazard Considerations 4.5 Other Hazards 4.6 Fire Protection and Life Safety 5 Types, Location, and Siting of Safe Rooms 5.1 Safe Room Types 5.2 Single-Use and Multi-Use Safe Rooms 5.3 Modifying and Retrofitting Existing Spaces 5.4 Community Safe Rooms for Neighborhoods 5.5 Community Safe Rooms at Public Facilities 5.6 Safe Room Site Selection 5.7 Locating Safe Rooms on Building Sites 6 Commentary on Load Determination and Structural Design Criteria 6.1 Commentary on the General Approach 6.2 Commentary on Load Combinations 6.3 Commentary on Tornado Community Safe Room Design Criteria 6.4 Commentary on Hurricane Community Safe Room Design Criteria 6.5 Commentary on Residential Safe Room Design Criteria 6.6 Commentary on Continuous Load Path Concepts 6.7 Anchorages and Connections 7 Commentary on Debris Impact Performance Criteria for Safe Rooms 7.1 Windborne Debris in Tornadoes and Hurricanes 7.2 Commentary on Resistance to Missile Loads and Successful Testing Criteria 7.3 Commentary on Performance of Wall and Roof Assemblies During Debris Impact Tests 7.4 Commentary on General Performance of Doors, Door Frames, and Windows During Debris Impact Tests 7.5 Commentary on Soil Protection From Debris Impact 7.6 Commentary on Large Falling Debris 8 Human Factors Criteria 8.1 Protection of Critical Support Systems 8.2 Occupancy Duration 8.3 Ventilation 8.4 Square Footage, Occupancy, and Egress Recommendations 8.5 Distance and Travel Time 8.6 Americans with Disabilities Act (ADA) 8.7 Special Needs 8.8 Lighting 8.9 Emergency Provisions 8.10 Standby Power 9 Emergency Management Considerations 9.1 Community Safe Room Operations Plan 9.2 Community Safe Room Maintenance Plan 9.3 Commercial or Public Building Safe Room Operations Plan 9.4 Signage 10 References Appendices APPENDIX A Acknowledgments APPENDIX B Safe Room Assessment and Design Tools APPENDIX C Case Study I – Stand-Alone Community Safe Room (North Carolina) APPENDIX D Case Study II – School Community Safe Room (Kansas) APPENDIX E Wall Sections That Passed Previous Missile Impact Tests APPENDIX F Doors and Hardware That Passed Previous Missile Impact Tests APPENDIX G Design Guidance on Missile Impact Protection Levels for Wood Sheathing APPENDIX H Acronyms and Abbreviations