Taking Shelter from the Storm Building a Safe Room for Your Home or Small Business Includes Construction Plans FEMA P-320, Fourth Edition / December 2014 Taking Shelter from the Storm Building a Safe Room for Your Home or Small Business Includes Construction Plans FEMA P-320, Fourth Edition / December 2014 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 The Federal Emergency Management Agency (FEMA) is pleased to have this opportunity to update and improve the guidance through this new edition of FEMA P-320, Taking Shelter from the Storm: Building a Safe Room for Your Home or Small Business. Since the first edition of FEMA P-320 was issued in 1998, more than 1 million copies of the publication have been distributed, and nearly 25,000 residential safe rooms have been constructed with FEMA funding assistance. Other positive developments include but are not limited to: • The construction of tens of thousands of safe rooms with private funds. • The International Code Council’s (ICC’s) release of a consensus standard on the design and construction of storm shelters. This standard, the ICC/NSSA Standard for the Design and Construction of Storm Shelters (ICC 500) is a referenced standard in the 2009, 2012, and 2015 International Building Code and International Residential Code. TAKING SHELTER FROM THE STORM i Building a Safe Room for Your Home or Small Business CONTENTS Preface .................................................................................................................................................................... i Acronyms ................................................................................................................................................................. vii Chapter 1.. Introduction ............................................................................................................................................. 1 Chapter 2. Understanding the Hazards .................................................................................................................... 5 2.1 Tornadoes ........................................................................................................................................ 5 2.2 Hurricanes ....................................................................................................................................... 8 2.3 Effects of Extreme Winds on a Building ......................................................................................10 2.4 Do You Need a Safe Room? ...........................................................................................................11 2.5 Assessing Your Risk ........................................................................................................................13 Chapter 3. Planning Your Safe Room ..................................................................................................................... 15 3.1 Design Basis ................................................................................................................................... 15 3.2 Flood Hazard Siting and Elevation ...............................................................................................16 3.2.1 Flood Hazard Siting Criteria .............................................................................................16 3.2.2 Flood Hazard Elevation Criteria .......................................................................................17 3.3 New versus Existing Homes or Buildings .....................................................................................17 3.4 Safe Room Size ...............................................................................................................................19 3.5 Safe Room Locations .................................................................................................................... 20 3.5.1 Siting Your Safe Room: Inside or Outside? ..................................................................... 20 3.5.2 Siting a Safe Room Inside a Home or Small Business .....................................................21 3.6 Floor Plans Showing Possible Safe Room Locations .................................................................. 23 3.6.1 Floor Plan 1: Basement ..................................................................................................... 23 3.6.2 Floor Plan 2: Safe Rooms on the Primary Level of a Home or Small Business ............ 23 3.6.3 Floor Plan 3: In-Ground Safe Rooms .............................................................................. 23 3.6.4 Floor Plan 4: Multipurpose Safe Rooms in a Small Business .........................................24 3.6.5 Selection of Safe Room Type and Location .....................................................................24 3.7 Foundation Type ........................................................................................................................... 26 3.7.1 Basement Foundation Applications ................................................................................. 26 3.7.2 Slab-on-Grade Applications ............................................................................................. 27 3.7.3 Crawlspace or Pile Applications ....................................................................................... 28 TAKING SHELTER FROM THE STORM iii Building a Safe Room for Your Home or Small Business 3.8 Construction Materials ................................................................................................................. 29 3.9 Safe Room Doors ........................................................................................................................... 30 3.9.1 What Should You Look for in a Door? ............................................................................. 30 3.9.2 Why Does the Door Cost So Much? ................................................................................. 32 3.10 Safe Room Cost ............................................................................................................................. 32 Chapter 4. Building Your Safe Room ...................................................................................................................... 35 4.1 Design Drawings ........................................................................................................................... 35 4.2 How to Use the Drawings ............................................................................................................. 36 4.2.1 Additional Requirements for Community Safe Rooms (Serving Small Businesses or More Than 16 Residential Occupants) .................................................... 37 4.2.2 Seismic Risks ...................................................................................................................... 38 4.3 Consumer Guide ........................................................................................................................... 38 4.4 Emergency Planning and Emergency Supply Kit ....................................................................... 40 4.5 Additional Resources .................................................................................................................... 42 Chapter 5. Safe Rooms Save Lives ........................................................................................................................... 43 Chapter 6. References .............................................................................................................................................. 49 Appendix A. Acknowledgments ...................................................................................................................................51 Appendix B. Tornado Safe Room Door Fact Sheet ................................................................................................... 53 List of Figures Figure 2-1: Typical tornado damage according to the EF Scale (wind speeds are estimated 3-second-gust wind speeds) ......................................................................................................................... 6 Figure 2-2: Recorded EF3, EF4, and EF5 tornadoes in the United States from 1950 to 2013 .................................... 7 Figure 2-3: Storm surge ................................................................................................................................................... 8 Figure 2-4: Typical damage associated with hurricane categories according to the Saffir-Simpson Hurricane Wind Scale (wind speeds are 1-minute sustained speeds) ..................................................... 9 Figure 2-5: Effect of extreme winds on building roof and walls .................................................................................10 Figure 2-6: Example of a garage door failure that initiated progressive failure, including loss of the garage roof ........................................................................................................................................10 TAKING SHELTER