FEMA

FEMA 424

Risk Management Series

Design Guide 

for Improving School Safety in Earthquakes, Floods, 

and High Winds

January 2004

FOREWORD AND ACKNOWLEDGMENTS

FOREWORD AND ACKNOWLEDGMENTS i

BACKGROUND

Our society places great importance on the education 

system and its schools, and has a tremendous investment 

in current and future schools. Currently, approximately 

53 million kindergarten to grade 12 (K-12) students attend over 

92,000 public schools and it is estimated that the public student 

population will have reached 54.3 million by 20041; to this figure 

must be added the substantial population of private school students. The sizes of these school facilities range from one-room 

rural schoolhouses to citywide and mega schools that house 5,000 

or more students. The school is both a place of learning and an 

important community resource and center.

This publication is concerned with the protection of schools and 

their occupants against natural hazards. These hazards must be 

recognized as part of the natural environment and as extensions 

of phenomena that designers have always considered. Natural hazards can be reduced to extreme phenomena related to the four 

elements (i.e., earth, water, wind, and fire). Earthquakes are highly 

accelerated and exaggerated forms of motion that are always occurring in the earth and floods occur when rivers overflow or the wind 

stirs up the ocean along coastal waters. High winds and tornadoes 

are an extreme form of the beneficial breezes that freshen the air. 

Fire has been a threat to buildings for centuries and was one of the 

first threats to be the subject of regulation. Because of its familiarity 

and the extensive provisions for fire protection in building codes, it 

is not a subject for detailed consideration in this publication. However, some considerations relating to the fire protection of schools 

are presented in Chapter 3, Section 3.4. 

Architects and engineers deal with these natural elements all the 

time; building codes always have provisions for protection against 

fire and wind and the local building code (if adopted by the com1 U.S. Department of Education, National Center for Education Statistics, Baby Boom Echo Report, 2000.
ii FOREWORD AND ACKNOWLEDGMENTS 

munity) will also dictate whether earthquakes or floods must be 

considered as design parameters. However, the major decisions in 

reducing flood damage may be in site selection and layout, not in 

building design. 

This manual introduces two core concepts: multihazard design 

and performance-based design. Neither is revolutionary, but represents an evolution in design thinking that is in tune with the 

increasing complexity of today’s buildings and also takes advantage of developments and innovations in building technology:

❍ The concept of multihazard design is that designers need to 

understand the fundamental characteristics of hazards and 

how they interact, so that design for protection becomes 

integrated with all the other design demands.

❍ Performance-based design suggests that, rather than relying 

on the building code for protection against hazards, a more 

systematic investigation is conducted to ensure that the 

specific concerns of building owners and occupants are 

addressed. Building codes focus on providing life safety and 

property protection is secondary: performance-based design 

provides additional levels of protection that cover property 

damage and functional interruption within a financially 

feasible context. 

This publication stresses that identification of hazards and their 

frequency and careful consideration of design against hazards 

must be integrated with all other design issues, and be present 

from the inception of the site selection and building design 

process. Although the basic issues to be considered in planning 

a school construction program are more or less common to all 

school districts, the processes used differ greatly, because each 

school district has its own approach. Districts vary in size, from 

a rural district responsible for only a few elementary schools, to 

a city district or statewide system overseeing a complex program 

of all school types and sizes, including new design and construction, renovations, and additions. A district may have had a 
FOREWORD AND ACKNOWLEDGMENTS iii

long-term program of school construction and be familiar with 

programming, financing, hiring designers, bidding procedures, 

contract administration, and commissioning a new building, but 

another district may not have constructed a new school for decades, and have no staff members familiar with the process.

SCOPE 

This publication is intended to provide design guidance for the 

protection of school buildings and their occupants against natural 

hazards, and concentrates on grade schools (K-12); the focus is on 

the design of new schools, but the repair, renovation, and extension of existing schools is also addressed. It is intended as the first 

of a series of publications in which hospitals, higher education 

buildings, multifamily dwellings, commercial buildings, and light 

industrial facilities will be addressed. 

The focus of this publication is on the safety of school buildings 

and their occupants, and the economic losses and social disruption caused by building damage and destruction. The volume 

covers three main natural hazards that have the potential to result 

in unacceptable risk and loss: earthquakes, floods, and high winds. 

A companion volume, Primer to Design Safe School Projects in Case of 

Terrorist Attacks (FEMA 428), covers the manmade hazards of physical, chemical, biological, and radiological attacks.

The intended audience for this manual includes design 

professionals and school officials involved in the technical and 

financial decisions of school construction, repair, and renovations. 

A short brochure based on this manual will also be available for 

school district and school board decision-makers.

ORGANIZATION AND CONTENT OF THE MANUAL

Chapters 1-3 present issues and background information that are 

common to all hazards. Chapters 4-6 cover the development of 

specific risk management measures for each of the three main 

natural hazards.
iv FOREWORD AND ACKNOWLEDGMENTS 

Chapter 1 opens with a brief outline of the past, present, and 

future of school design. Past school design is important because 

many of these older, and even historic, schools are still in use and 

their occupants must be protected. 

Chapter 2 introduces the concepts of performance-based design 

in order to obtain required performance from a new or retrofitted 

facility. Chapter 3 introduces the concept of multihazard design 

and presents a general description and comparison of the hazards, including charts that show where design against each hazard 

interacts with design for other hazards. This latter section includes 

fire and building security in its considerations.

Chapters 4, 5, and 6 outline the steps necessary in the creation 

of design to address risk management concerns for protection 

against earthquakes, floods, and high winds, respectively. Information is presented on the nature of each hazard and its effect on 

vulnerability and consequences of building exposure. Procedures 

for risk assessment are outlined, followed by descriptions of current methods of reducing the effects of each hazard. These vary, 

depending on the hazard under consideration. A guide to the 

determination of acceptable risk and realistic performance objectives is followed by a discussion to establish the effectiveness of 

current codes to achieve acceptable performance.

Appendix A contains a list of acronyms that appear in this manual.

The information presented in this publication provides a comprehensive survey of the methods and processes necessary to create 

a safe school, but is necessarily limited. It is not expected that the 

reader will be able to use the information directly to develop plans 

and specifications. The information is intended to help designers 

and facility decision-makers, who may be unfamiliar with the concepts involved, to understand fundamental approaches to risk 

mitigation planning and design. By so doing, they can move on to 

the implementation phase of detailed planning, involving consultants, procurement personnel, and project administration, from a 

firm basis of understanding. 
FOREWORD AND ACKNOWLEDGMENTS v

ACKNOWLEDGMENTS

Principal Authors:

Christopher Arnold, Building Systems Development, Inc.

Jack Lyons, School Facilities Consultant

James Munger, James G. Munger and Associates

Rebecca C. Quinn, Consultant

Thomas L. Smith, TLSmith Consulting

Contributors:

Milagros Kennett, FEMA, Project Officer, Risk Management 

Series Publications

Eric Letvin, Greenhorne & O’Mara, Inc., Consultant 

Project Manager

John Plisich, FEMA

Mike Robinson, FEMA

Joe Agron, American School and University

Connie Deshpande, Department of Education

Randy Haslam, Jordan, Utah, School District

Danny Kilcollins, Florida Department of Community Affairs

Fred Krimgold, World Institute for Disaster Risk 

Management

Tom Kube, Council of Educational Facility Planners 

International

Bill Modzeleski, Department of Education

Jack Paddon, Williams and Paddon Architects and Planners

Bebe Pinter, Harris County Department of Education

John Sullivan, Portland Cement Association

Jon Traw, Traw Associates 
vi FOREWORD AND ACKNOWLEDGMENTS

French Wetmore, French and Associates

Deb Daly, Greenhorne & O’Mara, Inc.

Wanda Rizer, Greenhorne & O’Mara, Inc.

Julie Liptak, Greenhorne & O’Mara, Inc.

Bob Pendley, Greenhorne & O’Mara, Inc.

This primer will be revised periodically and EP&R welcomes 

comments and feedback to improve future editions. 

Please send comments and feedback via e-mail to 

riskmanagementseriespubs@dhs.gov
TABLE OF CONTENTS

TABLE OF CONTENTS vii

FOREWORD AND ACKNOWLEDGMENTS...................................................... i

Background......................................................................................... i

Scope ................................................................................................. iii

Organization and Content of the Manual...................................... iii

Acknowledgments..............................................................................iv

CHAPTER 1– AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION 

PROCESS

1.1 Introduction.......................................................................... 1-1

1.2 School Construction: The National Picture ....................... 1-1

1.3 Past School Design................................................................ 1-2

1.4 Present School Design.......................................................... 1-9

1.5 Future School Design ......................................................... 1-10

1.6 The Design and Construction Process .............................. 1-12

1.7 School Design and Construction ...................................... 1-16

1.7.1 Structure ................................................................. 1-16

1.7.2 Nonstructural Systems and Components............. 1-17

CHAPTER 2 – DESIGNING FOR PERFORMANCE ........................................ 2-1

2.1 Introduction.......................................................................... 2-1

2.2 Definitions of Performance-based Design .......................... 2-1

2.3 The Prescriptive Approach to Codes .................................. 2-2

2.4 The Performance-based Approach...................................... 2-3

2.5 Hazard, Risk, and Probability............................................... 2-6

2.6 Acceptable Risk and Performance Levels .......................... 2-9

2.7 Correlation Between Performance Groups 

and Tolerated Levels of Damage ....................................... 2-10
viii TABLE OF CONTENTS 

2.8 Roles of Designers, Code Officials, and 

the School District .............................................................. 2-13

2.9 Changes to a Building Designed for 

Performance........................................................................ 2-14

2.10 Current Performance-based Codes ................................... 2-15

2.11 The O&M Manual and the Occupants’ 

Handbook............................................................................ 2-17

2.12 Performance-based Design for 

Natural Hazards .................................................................. 2-19

2.12.1 Performance-based Seismic Design...................... 2-23

2.12.2 Performance-based Flood Design......................... 2-30

2.12.3 Performance-based High Wind 

and Tornado Design .............................................. 2-32

CHAPTER 3 – MULTIHAZARD DESIGN ..................................................... 3-1

3.1 Introduction.......................................................................... 3-1

3.2 The Hazards Compared......................................................... 3-1

3.2.1 Location: Where are They? ..................................... 3-2

3.2.2 Warning: How Much Time 

is There?.................................................................... 3-6

3.2.3 Frequency: How Likely 

are They to Occur?................................................... 3-6

3.2.4 Risk: How Dangerous are They? ............................. 3-8

3.2.5 Cost: How Much Damage 

Will They Cause? .................................................... 3-10

3.3 Comparative Losses............................................................. 3-11

3.4 Fire and Life Safety ............................................................. 3-16

3.5 Hazard Protection Methods Comparisons: 

Reinforcements and Conflicts............................................ 3-19
TABLE OF CONTENTS ix

CHAPTER 4 –MAKING SCHOOLS SAFE AGAINST EARTHQUAKES................. 4-1

4.1 Introduction.......................................................................... 4-1

4.2 The Nature and Probability of Earthquakes ..................... 4-1

4.2.1 Earthquakes and Other Geologic Hazards ............ 4-1

4.2.2 Earthquakes: A National Problem .......................... 4-3

4.2.3 Determination of Local Earthquake 

Hazards ................................................................... 4-11

4.3 Vulnerability: What Earthquakes Can 

Do to Schools ...................................................................... 4-15

4.3.1 Vulnerability of Schools ....................................... 4-15

4.3.2 Earthquake Damage to Schools ........................... 4-20

4.3.3 Significant School Damage in Recent 

U.S. Earthquakes.................................................... 4-27

4.3.4 Consequences: Casualties, Financial 

Loss, and Operational Disruption ........................ 4-32

4.4 Scope, Effectiveness, and Limitations of Codes................ 4-33

4.4.1 The Background of Seismic Codes....................... 4-34

4.4.2 Seismic Codes and Schools.................................... 4-36

4.4.3 The Effectiveness of Seismic Codes ..................... 4-37

4.5 Evaluating Existing Schools for Seismic 

Risk and Specific Risk Reduction Methods....................... 4-38

4.5.1 Rapid Visual Screening.......................................... 4-38

4.5.2 Systems Checklist for School Seismic 

Safety Evaluation .................................................... 4-41

4.5.3 The NEHRP Handbook for 

the Seismic Evaluation of Existing 

Buildings (FEMA 178/310) .................................. 4-47

4.6 Earthquake Risk Reduction Methods................................ 4-48
x TABLE OF CONTENTS 

4.6.1 Risk Reduction for New Schools........................... 4-49

4.6.2 Risk Reduction for Existing Schools..................... 4-61

4.7 The School as a Post-earthquake Shelter .......................... 4-69

4.8 References and Sources of Additional Information......... 4-71

4.9 Glossary of Earthquake Terms ........................................... 4-72

CHAPTER 5 – MAKING SCHOOLS SAFE AGAINST FLOODS.......................... 5-1

5.1 Introduction.......................................................................... 5-1

5.2 Nature and Probability of Floods......................................... 5-1

5.2.1 Characteristics of Flooding ..................................... 5-3

5.2.2 Probability of Occurrence ....................................... 5-7

5.2.3 Hazard Identification and Flood Data.................... 5-8

5.2.4 Design Flood Elevation.......................................... 5-13

5.3 Scope, Effectiveness, and Limitations 

of Building Codes and Floodplain 

Management Requirements .............................................. 5-14

5.3.1 Overview of the NFIP............................................. 5-14

5.3.2 Summary of the NFIP Minimum 

Requirements ........................................................ 5-16

5.3.3 Model Building Codes and Standards ................. 5-18

5.4 Risk Reduction: Avoiding Flood Hazards ........................ 5-19

5.4.1 Benefits/Costs: Determining 

Acceptable Risk ...................................................... 5-20

5.4.2 Identifying Flood Hazards at School Sites............ 5-22

5.5 Risk Reduction: Flood-resistant New Schools.................. 5-26

5.5.1 Site Modifications................................................... 5-26

5.5.2 Elevation Considerations....................................... 5-28
TABLE OF CONTENTS xi

5.5.3 Floodproofing Considerations ............................. 5-31

5.5.4 Accessory Structures .............................................. 5-33

5.5.5 Utility Installations ................................................ 5-33

5.5.6 Potable Water and Wastewater Systems................ 5-34

5.5.7 Storage Tank Installations .................................... 5-34

5.5.8 Access Roads .......................................................... 5-35

5.6 Vulnerability: What Floods Can Do to 

Existing Schools .................................................................. 5-36

5.6.1 Site Damage............................................................ 5-36

5.6.2 Structural Damage ................................................. 5-37

5.6.3 Saturation Damage................................................. 5-40

5.6.4 Utility System Damage ........................................... 5-42

5.6.5 Contents Damage................................................... 5-45

5.7 Risk Reduction: Protecting Existing Schools................... 5-46

5.7.1 Site Modifications .................................................. 5-48

5.7.2 Additions ................................................................ 5-51

5.7.3 Repairs, Renovations, and Upgrades.................... 5-52

5.7.4 Retrofit Dry Floodproofing ................................... 5-53

5.7.5 Utility Installations ................................................ 5-53

5.7.6 Potable Water and Wastewater Systems................ 5-56

5.7.7 Other Damage Reduction Measures ................... 5-57

5.7.8 Emergency Measures ............................................. 5-57

5.8 The School as an Emergency Shelter ................................ 5-59

5.9 References and Sources of 

Additional Information ...................................................... 5-60

5.10 Glossary of Flood Protection Terms .................................. 5-63
xii TABLE OF CONTENTS 

CHAPTER 6 – MAKING SCHOOLS SAFE AGAINST WINDS........................... 6-1

6.1 Introduction.......................................................................... 6-1

6.2 The Nature and Probability of High Winds........................ 6-2

6.2.1 Wind/Building Interactions ................................... 6-6

6.2.2 Probability of Occurrence ..................................... 6-15

6.3 Vulnerability: What Wind Can Do to Schools ................. 6-17

6.4 Scope, Effectiveness, and Limitations 

of Building Codes ............................................................... 6-23

6.4.1 Scope....................................................................... 6-24

6.4.2 Effectiveness ........................................................... 6-25

6.4.3 Limitations.............................................................. 6-25

6.5 Priorities, Costs, and Benefits: New Schools ..................... 6-27

6.5.1 Priorities.................................................................. 6-27

6.5.2 Cost, Budgeting, and Benefits............................... 6-28

6.6 Priorities, Costs, and Benefits: Existing 

Schools................................................................................. 6-30

6.6.1 Priorities.................................................................. 6-31

6.6.2 Cost, Budgeting, and Benefits............................... 6-32

6.7 Evaluating Schools for Risk from High Winds.................. 6-33

6.7.1 Tornadoes ............................................................. 6-35

6.7.2 Portable Classrooms ............................................. 6-36

6.8 Risk Reduction Design Methods ...................................... 6-36

6.8.1 Siting ....................................................................... 6-36

6.8.2 School Design ........................................................ 6-37

6.8.3 Peer Review............................................................. 6-42
TABLE OF CONTENTS xiii

6.8.4 Construction Contract Administration ................ 6-42

6.8.5 Post-occupancy Inspections, Periodic

Maintenance, Repair, and Replacement........................... 6-43

6.9 Structural Systems............................................................... 6-44

6.10 Exterior Doors..................................................................... 6-48

6.10.1 Loads and Resistance............................................. 6-48

6.10.2 Durability ................................................................ 6-48

6.10.3 Exit Door Hardware............................................... 6-49

6.10.4 Water Infiltration ................................................... 6-49

6.10.5 Weatherstripping.................................................... 6-50

6.11 Non-load Bearing Walls, Wall Coverings, Soffits, 

and Underside of Elevated Floors ..................................... 6-53

6.11.1 Loads and Resistance............................................. 6-53

6.11.2 Durability ................................................................ 6-55

6.11.3 Wall Coverings........................................................ 6-55

6.11.4 Underside of Elevated Floors................................ 6-59

6.12 Roof Systems........................................................................ 6-59

6.13 Windows and Skylights ....................................................... 6-68

6.13.1 Loads and Resistance............................................. 6-68

6.13.2 Durability ................................................................ 6-69

6.13.3 Water Infiltration ................................................... 6-69

6.14 Exterior-mounted Mechanical, Electrical, 

and Communications Equipment ..................................... 6-71

6.14.1 Loads and Attachment........................................... 6-72

6.14.2 Equipment Strength .............................................. 6-74

6.14.3 Durability .............................................................. 6-76
xiv TABLE OF CONTENTS 

6.15 Schools Located in Hurricane-prone Regions ................. 6-79

6.15.1 Design Loads ........................................................ 6-80

6.15.2 Structural Systems ................................................ 6-80

6.15.3 Exterior Doors........................................................ 6-80

6.15.4 Non-load Bearing Walls, Wall Coverings, 

and Soffits ............................................................. 6-81

6.15.5 Roof Systems........................................................... 6-81

6.15.6 Windows and Skylights........................................... 6-84

6.15.7 Emergency Power................................................... 6-86

6.15.8 Construction Contract Administration ................ 6-86

6.15.9 Periodic Inspections, Maintenance, 

and Repair .............................................................. 6-86

6.16 Design for Tornado Shelters.............................................. 6-88

6.17 Remedial Work on Existing Schools.................................. 6-91

6.18 References and Sources of Additional 

Information ........................................................................ 6-94

6.19 Glossary of Wind Terms...................................................... 6-96

APPENDIX A – ACRONYMS

TABLES

CHAPTER 2

Table 2-1: ICC Performance Code Criteria for 

Seismic, Flood, and Wind Events............................. 2-8

Table 2-2: Performance Groups and Tolerated 

Levels of Damage .................................................... 2-11

Table 2-3: Seismic Expectations Checklist ............................. 2-26

Table 2-4: Damage Control and Building 

Performance Levels................................................. 2-28
TABLE OF CONTENTS xv

CHAPTER 3

Table 3-1 HAZUS-MH Earthquake, Hurricane, 

and Flood Losses..................................................... 3-13

Table 3-2 HAZUS-MH Estimated Losses by 

Percentage of School Building and 

Contents Inventory.................................................. 3-15

Table 3-3 Multihazard Design System Interactions............... 3-20

CHAPTER 4

Table 4-1: Known Historic (1568-1989) Earthquakes 

in 47 U.S. States......................................................... 4-5

Table 4-2: School Seismic Safety Evaluation Checklist........... 4-42

Table 4-3: Roofing Maintenance and Repair/

Re-roofing ................................................................ 4-67

CHAPTER 5

Table 5- 1: Flood Hazards at School Sites ................................ 5-22

Table 5-2: Characteristics of Existing School 

Buildings.................................................................. 5-47

CHAPTER 6

Table 6-1: Summation of Risk Reduction 

Design Methods....................................................... 6-76

Table 6-2: Summation of Design of Schools Used 

for Hurricane Shelters and/or for 

Emergency Response After a Storm ...................... 6-87

Table 6-3: Summation of Design for Tornado 

Shelters..................................................................... 6-90

Table 6-4: Summation of Remedial Work on 

Existing Schools....................................................... 6-93
xvi TABLE OF CONTENTS 

FIGURES

CHAPTER 1

Figure 1-1 One-room schoolhouse, 

Christiana, DE, 1923 ................................................. 1-3

Figure 1-2 High school, New York City, 1929 ............................ 1-3

Figure 1-3 Elementary school, Washington, DC, 1930............. 1-4

Figure 1-4 Typical finger plan school, 1940s. 

In California, the access hallways would 

be open to the air. The cross-section 

diagram shows the simple and effective 

day lighting and ventilation...................................... 1-5

Figure 1-5 Compact courtyard plan, 1960s................................ 1-5

Figure 1-6 Fountain Valley High School, Huntington 

Beach, CA, 1964 (330 students)............................... 1-6

Figure 1-7 Open enclosure plan teaching area, 

with movable screens and storage, 

Rhode Island, 1970 ................................................... 1-7

Figure 1-8 Typical modular classrooms, 1980s, 

still in use ................................................................... 1-7

Figure 1-9 Elementary school, Fairfield, PA, 1980s .................. 1-8

Figure 1-10 Private high school, Palo Alto, CA, 

located in a remodeled industrial building.

Note the exterior cross bracing; the 

building required extensive retrofitting 

to meet school seismic requirements....................... 1-8

Figure 1-11 West High School, Aurora, IL, 2000 ...................... 1-10

Figure 1-12 Elementary school, Oxnard, CA, 2000 .................. 1-11

Figure 1-13 The design and construction process 

flow chart ................................................................. 1-15
TABLE OF CONTENTS xvii

CHAPTER 2

Figure 2-1 Performance-based design approach 

flow chart ................................................................ 2-12

CHAPTER 3

Figure 3-1 Peak accelerations (%g) with 10 percent 

probability of exceedance in 50 years. 

Color code shows %g for areas between 

contour lines. These values are used for 

seismic design. ........................................................... 3-4

Figure 3-2 Presidential Disaster Declarations for 

floods, January 1965 to November 2000.

The incidence of declarations is shown 

by counties. ................................................................ 3-4

Figure 3-3 Presidential Disaster Declarations for 

hurricanes, January 1965 to November 

2000. The incidence of declarations is 

shown by counties. .................................................... 3-5

Figure 3-4 Presidential Disaster Declarations for 

tornadoes, January 1965 to November 

2000. The incidence of declarations is 

shown by counties. .................................................... 3-5

CHAPTER 4

Figure 4-1 School, Anchorage, AK, 1964, severely 

damaged by earthquake-induced landslide............. 4-3

Figure 4-2 Map of the continental United States 

that shows counties and probabilities 

of earthquakes of varying magnitude ...................... 4-4

Figure 4-3 Map showing older seismic zones in 

part of the United States, from the 1997 

Uniform Building Code. The area in the 

box corresponds to the area in Figure 4-4............. 4-12
xviii TABLE OF CONTENTS 

Figure 4-4 Portion of an earthquake ground motion 

map used in the International Building 

Code 2003 that shows contours that identify 

regions of similar spectral response 

accelerations to be used for seismic design. 

Spectral response acceleration includes 

both ground acceleration and effect of 

building period........................................................ 4-13

Figure 4-5 These maps compare the seismicity 

of the Southeast U.S. and California. 

The larger acceleration values for the latter 

are symbolized by the darker colors. ..................... 4-14

Figure 4-6 These maps show a comparison for the 

Southeast U.S. between the acceleration 

values for a 1-second (long) and a 

0.2-second (short) building period........................ 4-14

Figure 4-7 Ductility ................................................................. 4-15

Figure 4-8 Collapse of portion of nonductile 

concrete frame school structure, Helena, 

MT, 1935 .................................................................. 4-16

Figure 4-9 Modular classrooms pushed off their 

foundations; note stairs at left, 

Northridge, CA, 1994.............................................. 4-17

Figure 4-10 Fallen filing cabinets and shelves, 

Northridge, CA, 1994.............................................. 4-17

Figure 4-11 Fallen shop equipment, Coalinga, 

CA, 1983................................................................... 4-18

Figure 4-12 Fallen light fixtures, library, Coalinga, 

CA, 1983................................................................... 4-19

Figure 4-13 Fallen heavy lath and plaster ceiling 

across auditorium seating, Northridge, 

CA, 1994................................................................... 4-19
TABLE OF CONTENTS xix

Figure 4-14 Damage to the John Muir School, Long 

Beach, CA, 1933 ...................................................... 4-20

Figure 4-15 Damage to shop building, Compton 

Junior High School, Long Beach, CA, 

1933 .......................................................................... 4-21

Figure 4-16 A dangerous passage way between 

two buildings, Polytechnic High School, 

Long Beach, CA, 1933 ............................................ 4-23

Figure 4-17 A heavy corridor lintel ready to fall, 

Emerson School, Bakersfield, 

Kern County, CA, 1952 ........................................... 4-23

Figure 4-18 Overturned shop equipment and failed 

light fixtures, Kern County, CA, 1952.................... 4-23

Figure 4-19 Destroyed exit corridor, Bakersfield, 

Kern County, CA, 1952 ........................................... 4-24

Figure 4-20 Typical school damage, Helena, MT, 1935............ 4-25

Figure 4-21 The student body president was killed 

here by falling brickwork, Seattle, WA, 

1949 .......................................................................... 4-25

Figure 4-22 Another dangerous entry collapse, 

Seattle, WA, 1949..................................................... 4-26

Figure 4-23 Collapse of roof over stage, 

Seattle, WA, 1949..................................................... 4-26

Figure 4-24 Damage to library shelving, 

Seattle, WA, 1949..................................................... 4-27

Figure 4-25 Severe structural damage to the 

West Anchorage High School, 

Anchorage, AK, 1964 .............................................. 4-28

Figure 4-26 Brittle failure at nonductile 

concrete column, West Anchorage 

High School, 1964................................................... 4-28
xx TABLE OF CONTENTS 

Figure 4-27 Ceiling damage, Northridge, CA, 1994 ................. 4-30

Figure 4-28 Damage to ceramic kiln, including 

fractured gas line, Northridge, CA, 1994 .............. 4-31

Figure 4-29 Line of suspended light fixtures fallen 

on teacher’s station, Northridge, CA, 

1994 .......................................................................... 4-31

Figure 4-30 Example of rapid visual screening 

information form .................................................... 4-40

Figure 4-31 The structural and nonstructural 

components............................................................. 4-59

Figure 4-32 Suspended ceiling and light fixture 

bracing and support................................................ 4-60

Figure 4-33 Bracing tall shelving to the structure..................... 4-60

Figure 4-34 Connection of nonstructural masonry 

wall to structure to permit independent 

movement ................................................................ 4-60

Figure 4-35 Bracing for existing unreinforced 

masonry parapet wall .............................................. 4-61

Figure 4-36 Design strategies for seismic retrofit of 

existing buildings .................................................... 4-63

Figure 4-37 Retrofit of B.F. Day Elementary School, 

Seattle, WA............................................................... 4-65

Figure 4-38 Sections and plans of the B.F. Day School: 

existing at bottom, retrofitted at top ..................... 4-65

CHAPTER 5

Figure 5-1 The riverine floodplain............................................. 5-3

Figure 5-2 The coastal floodplain ............................................. 5-4

Figure 5-3 Riverine flood hazard zones................................... 5-12

Figure 5-4 Definition sketch – flood elevations ...................... 5-13
TABLE OF CONTENTS xxi

Figure 5-5 A high school in Bloomsburg, PA, 

elevated on fill ......................................................... 5-29

Figure 5-6 Elementary school in Jefferson County, 

OH, elevated on columns....................................... 5-30

Figure 5-7 Hydrostatic force diagram...................................... 5-39

Figure 5-8 Fractured concrete basement floor, 

Gurnee, IL, 1986 ..................................................... 5-39

Figure 5-9 Damaged walls and cabinets, 

Peoria County, IL .................................................... 5-42

Figure 5-10 Basement damage at a grade school in 

Gurnee, IL, 1986 ..................................................... 5-42

Figure 5-11 Schematic of typical earthen levee 

and permanent floodwall ....................................... 5-49

Figure 5-12 Masonry floodwall with multiple 

engineered closures at Oak Grove 

Lutheran School, Fargo, ND ................................. 5-50

Figure 5-13 Elevated electric transformer at 

an elementary school in Verret, LA ....................... 5-54

Figure 5-14 Elevated utilities behind an elementary 

school in Wrightsville Beach, NC........................... 5-55

CHAPTER 6

Figure 6-1 Hurricane-prone regions and special 

wind regions .............................................................. 6-2

Figure 6-2 Tornado occurrence in the United States 

based on historical data ............................................ 6-5

Figure 6-3 Design wind speeds for community 

tornado shelters ........................................................ 6-6

Figure 6-4 Schematic of wind-induced pressures on 

a building................................................................... 6-7
xxii TABLE OF CONTENTS 

Figure 6-5 Schematic of internal pressure condition 

when the dominant opening is in the 

windward wall .......................................................... 6-10

Figure 6-6 Schematic of internal pressure condition 

when the dominant opening is in the 

leeward wall.............................................................. 6-11

Figure 6-7 Relative roof uplift pressures as a function 

of roof geometry, roof slope, and location 

on roof, and relative positive and negative 

wall pressures as a function of location 

along the wall........................................................... 6-13

Figure 6-8 The aggregate ballast on this single-ply 

membrane roof was blown away in the 

vicinity of the corners of the wall 

projections at the window bays. The 

irregular wall surface created turbulence, 

which led to wind speed-up and loss of 

aggregate in the turbulent flow areas.................... 6-14

Figure 6-9 The metal roof is over a stair tower. 

The irregularity created by the stair tower 

caused turbulence that resulted in wind 

speed-up................................................................... 6-14

Figure 6-10 This high school in northern Illinois was 

heavily damaged by a strong tornado .................... 6-17

Figure 6-11 A portion of the built-up membrane at 

this school lifted and peeled after the 

metal edge flashing lifted. The cast-in-place 

concrete deck kept a lot of water from 

entering the school. Virtually all of 

the loose aggregate blew off the roof and 

broke many windows in nearby houses. 

This school was being used as a hurricane 

shelter at the time of the blow-off. ......................... 6-18
TABLE OF CONTENTS xxiii

Figure 6-12 The outer panes of these windows were 

broken by aggregate from a built-up roof. 

The inner panes had several impact craters. 

In several of the adjacent windows, both 

the outer and inner panes were broken. 

The aggregate had a flight path in excess 

of 245 feet. The wind speed was less than 

the design wind speed............................................. 6-18

Figure 6-13 The metal wall covering on this school 

was applied to plywood over metal studs.

The metal stud wall collapsed in this area, 

but, in other areas, it was blown completely 

away. The CMU wall behind the studs did 

not appear to be damaged. This school was 

on the periphery of a violent tornado. .................. 6-19

Figure 6-14 The unreinforced CMU wall at this school 

collapsed during a storm that had wind 

speeds that were less than the design 

wind speed ............................................................... 6-19

Figure 6-15 The roof and all the walls of a wing of this 

elementary school were blown away by a 

violent tornado ........................................................ 6-20

Figure 6-16 This portable classroom was blown up 

against the main school building during 

a storm that had wind speeds that were 

less than the design wind speed. Depending 

upon the type of exterior wall, an impacting 

portable classroom may or may not cause 

wall collapse. ........................................................... 6-20

Figure 6-17 This newly-constructed gymnasium had 

a structural metal roof panel (3-inch 

trapezoidal ribs at 24 inches on center) 

applied over metal purlins. The panels 

detached from their concealed clips. A 

massive quantity of water entered the school 

and buckled the wood gym floor............................ 6-21
xxiv TABLE OF CONTENTS 

Figure 6-18 A portion of the roof structure blew off 

of this school, and a portion of it collapsed 

into classrooms. Because of extensive water 

damage, a school such as this can be out of 

operation for a considerable period of time......... 6-23

Figure 6-19 The HVAC unit in the parking lot in the 

photo’s lower right corner blew off the curb 

during a storm that had wind speeds that 

were less than the design wind speed. 

A substantial amount of water entered the 

building before a temporary covering could 

be placed over the opening. .................................. 6-30

Figure 6-20 This figure illustrates load path continuity 

of the structural system. Members are sized 

to accommodate the design loads and 

connections are designed to transfer uplift 

loads applied to the roof, and the positive 

and negative loads applied to the exterior 

bearing walls down to the foundation and 

into the ground. ..................................................... 6-40

Figure 6-21 View of a steel joist after the metal 

decking blew away .................................................. 6-46

Figure 6-22 View of another weld near the weld 

shown in Figure 6-21 ............................................... 6-46

Figure 6-23 Portions of this waffled precast concrete 

roof deck were blown off. Bolts had been 

installed to provide uplift resistance; 

however, anchor plates and nuts had not 

been installed. ........................................................ 6-47

Figure 6-24 Several of the precast twin-Tee roof and 

wall panels collapsed. The connection between 

the roof and wall panels provided very little 

uplift load resistance. .............................................. 6-47
TABLE OF CONTENTS xxv

Figure 6-25 Door sill pan flashing with end dams, 

rear leg, and turned-down front leg ...................... 6-50

Figure 6-26 Drip at door head and drip with hook at head..... 6-50

Figure 6-27 Door shoe with drip and vinyl seal ........................ 6-51

Figure 6-28 Neoprene door bottom sweep ............................... 6-51

Figure 6-29 Automatic door bottom.......................................... 6-51

Figure 6-30 Interlocking threshold with drain pan ................. 6-52

Figure 6-31 Threshold with stop and seal ................................. 6-52

Figure 6-32 Adjustable jamb/head weatherstripping............... 6-53

Figure 6-33 This suspended metal soffit was not designed 

for upward-acting wind pressure............................ 6-54

Figure 6-34 The interior walls of this classroom wing 

were constructed of unreinforced CMU ............... 6-55

Figure 6-35 Failure of brick veneer............................................ 6-56

Figure 6-36 EIFS blow-off near a wall corner ............................ 6-57

Figure 6-37 The metal edge flashing on this modified 

bitumen membrane roof was installed 

underneath the membrane, rather than 

on top of it and then stripped in. In this 

location, the edge flashing is unable to 

clamp the membrane down.................................... 6-61

Figure 6-38 This metal edge flashing had a continuous 

cleat, but the flashing disengaged from 

the cleat and the vertical flange lifted up.

However, the horizontal flange of the flashing 

did not lift. .............................................................. 6-62

Figure 6-39 This coping was attached with 1⁄4-inch 

diameter stainless steel concrete spikes at 

12 inches on center. When the fastener is 

placed in wood, #14 stainless steel screws 

with stainless steel washers are recommended. .... 6-63
xxvi TABLE OF CONTENTS 

Figure 6-40 Continuous bar near the edge of edge 

flashing or coping. If the edge flashing or 

coping is blown off, the bar may prevent a 

catastrophic progressive failure.............................. 6-63

Figure 6-41 On this school, the fastener rows of the 

mechanically attached single-ply membrane 

ran parallel to the top flange of the steel 

deck. Hence, essentially all of the row’s 

uplift load was transmitted to only two deck 

fasteners at each joist ............................................. 6-66

Figure 6-42 View of the underside of a steel deck. 

The mechanically attached single-ply 

membrane fastener rows ran parallel to the 

top flange of the steel deck. ................................... 6-66

Figure 6-43 The parapet on this school was sheathed

with metal wall panels. The panels were 

fastened at 2 feet on center along their 

bottom edge, which was inadequate to resist 

the wind load. .......................................................... 6-67

Figure 6-44 This air terminal (“lightning rod”) was 

dislodged and whipped around during a 

windstorm. The single-ply membrane was 

punctured by the sharp tip in several 

locations................................................................... 6-68

Figure 6-45 Two complete windows, including their 

frames, blew out. The frames were attached 

with an inadequate number of fasteners, 

which were somewhat corroded............................. 6-69

Figure 6-46 View of a typical window sill pan flashing 

with end dams and rear legs. Windows that 

do not have nailing flanges should typically 

be installed over a pan flashing.............................. 6-70

Figure 6-47 Protection of sealant with a stop. The stop 

retards weathering of the sealant and reduces 

the wind-driven rain demand on the sealant. ....... 6-71
TABLE OF CONTENTS xxvii

Figure 6-48 The rooftop mechanical equipment on 

this school was blown over. The displaced 

equipment can puncture the roof membrane 

and, as in this case, rain can enter the school 

through the large opening that is no longer 

protected by the equipment. ................................. 6-72

Figure 6-49 This HVAC equipment had two supplemental 

securement straps. Both straps are still on this 

unit, but some of the other units on the roof 

had broken straps.................................................... 6-73

Figure 6-50 The communications mast on this school 

was pulled out of the deck, resulting in a 

progressive peeling failure of the fully 

adhered single-ply membrane. There are 

several exhaust fans in the background that 

were blown off their curbs, but were retained 

on the roof by the parapet...................................... 6-74

Figure 6-51 To overcome blow-off of the fan cowling, 

which is a common problem, this cowling 

was attached to the curb with cables. The 

curb needs to be adequately attached to 

carry the wind load exerted on the fan. ................ 6-75

Figure 6-52 These wire-tied tiles were installed over a 

concrete deck. They were attached with 

stainless steel clips at the perimeter rows 

and all of the tiles had tail hooks. Adhesive 

was also used between the tail and head 

of the tiles. .............................................................. 6-83

Figure 6-53 At this school, a missile struck the fully 

adhered low-sloped roof and slid into

the steep-sloped reinforced mechanically

attached single-ply membrane. A large 

area of the mechanically attached membrane 

was blown away due to progressive membrane

 tearing. .................................................................... 6-84
xxviii TABLE OF CONTENTS

Figure 6-54 This fully adhered single-ply membrane 

was struck by a large number of missiles 

during a hurricane .................................................. 6-84

Figure 6-55 View of a metal shutter designed to 

provide missile protection for windows................. 6-85

Figure 6-56 A violent tornado passed by this high 

school and showered the roof with 

missiles ..................................................................... 6-88

Figure 6-57 View of an elementary school corridor 

after passage of a violent tornado. Although 

corridors sometimes offer protection, they can 

be death traps as illustrated in this figure 

(fortunately the school was not occupied when 

it was struck). ........................................................... 6-90

Figure 6-58 This school had a cementitious woodfiber deck (commonly referred to by the 

proprietary name “Tectum”).................................. 6-92
AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION PROCESS 1

AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION PROCESS 1-1

1.1 INTRODUCTION

T his chapter presents an overview of the school building, 

to provide a context for the chapters that follow. Every 

building is unique and there is great variety in school 

design; however, the purpose of schools, their occupancy, their 

economic basis, and their role in the social scene mean that there 

are certain common features of schools that distinguish them 

from other building types.

A summary of the national public school inventory is presented 

(i.e., how many students it houses and how many schools it contains) and projections of future needs are also outlined. School 

design of the past is discussed, because many older schools are still in 

use and must be renovated periodically to meet today’s needs. The 

present state of school design is also discussed and some trends and 

ideas that might influence future schools are identified. 

1.2 SCHOOL CONSTRUCTION: 

THE NATIONAL PICTURE 

The estimated value of the national public school inventory is well 

over $361.6 billion.1 Of the almost 15,000 local education agencies found throughout the United States (U.S.), 41.9 percent are 

in small towns and rural areas, and enroll 30.4 percent of the students; 25.9 percent are in large towns and cities, and enroll 30.7 

percent of the students; and 32.2 percent of the education agencies are in suburban areas, and enroll 39 percent of the students.2

Over half of our school facilities are at least 40 years old3 and, even 

with minor renovations, have passed their prime in terms of adapt1 Conservative estimate based upon elementary and secondary school averages developed with the 

help of Paul Abramson, President of Stanton Leggett & Associates, Education Consultants. 

2 U.S. Department of Education, National Center of Education Statistics; The Digest of Education 

Statistics, 2001.

3 U.S. Department of Education, National Center of Education Statistics, The Digest of Education 

Statistics, 2001.
1-2 AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION PROCESS 

ability to modern teaching methods and tools (e.g., computers, 

in-class electronic information displays, and group learning activities). Almost all states require new construction once replacement 

costs reach a certain level (usually 60 percent4). The most recent 

studies (completed at the close of the last decade) show a range of 

$100 to over $300 billion would be needed to bring our nation’s 

schools into good teaching condition.

In 2001, the decade-long growth in kindergarten to grade 12 (K-12) 

school construction reached a peak. A propensity for deferred maintenance and the poor construction quality of many post-World War II 

schools have resulted in a huge renovation demand, and population 

increases mean that additional space will also be necessary.

If new construction, remodeled space, and additions are included, 2001 witnessed over $29.5 billion in school construction 

throughout the United States, with primary school projects 

slightly edging out high school projects in total number, but not 

in construction dollars. The overall school construction intensity 

dropped slightly to $28.2 billion, but is forecast to rise to $29.15 

billion by mid-decade. From 2001 through 2005, it is estimated 

that almost a billion square feet of either new, renovated, or additional square feet will be added to the national school inventory.

1.3 PAST SCHOOL DESIGN

Schools are typically in use for long periods of time; as a result, 

teaching continues to be conducted in facilities that were designed and constructed at the beginning of the 20th century. Early 

20th century school design was based on late 19th century models 

and was relatively static until after World War II. Schools ranged 

from one-room rural school houses to major symbolic civic structures in large cities. Other inner city schools were more modest, 

inserted into small sites on busy streets and constrained by budget 

limits (see Figures 1-1, 1-2, and 1-3).

4 Use of this estimate as a decision tool was developed by Basil Castoldi, Education Facilities, 

Planning, Modernization and Management, fourth edition, Allyn & Bacon publishers, page 385.
AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION PROCESS 1-3

Figure 1-1 

One-room schoolhouse, 

Christiana, DE, 1923

The typical city school was one to three stories in height and consisted of rows of classrooms on either side of a wide, noisy corridor 

lined with metal lockers; asphalt play courts; and, sometimes, 

rooftop recreational areas. The larger schools sometimes had a library, special rooms for art, science, and shop, and an auditorium.

The surge to meet the school construction demands of the post 

war baby-boom was primarily a suburban development. Much 

larger sites were available, schools were one or two stories in 

height, auditoriums became multiuse buildings, and large parking 

lots appeared. However, many rural schools were located far away 

from towns and their resources, such as fire departments and 

other services. 

Figure 1-2 

High school, New York City, 

1929

SKETCH BY: CHRIS ARNOLD

SKETCH BY: CHRIS ARNOLD
1-4 AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION PROCESS 

But the fundamental school program of classrooms along doubleloaded corridors did not change very much. However, in warm 

climates, the one-story finger plan school, constructed of wood 

and a small quantity of steel, was both economical and more 

human, and the noisy tiled double-loaded corridor became a covered walk, open to the air, with the classrooms on one side and a 

grassed court on the other (see Figure 1-4). Compact versions of 

these plans appeared as schools became larger and sites smaller 

(see Figure 1-5). 

Inner-city high schools were usually large facilities, housing 2,000 

to 3,000 students (basically small towns with complex social, economic, and class systems; see Figure 1-6). In the 1960s and 1970s, 

some design experiments were tried, such as team teaching, which 

spawned large open classrooms with poor acoustics (see Figure 

1-7). Some of the new large high schools were built as air-conditioned enclosures, with many windowless classrooms, in buildings 

similar to the shopping malls that replaced the main street retail 

centers (see Figure 1-7). At the same time, many schools were 

expanded by adding prefabricated classrooms to accommodate a 

surge in enrollment. Although the prefabricated classrooms were 

originally intended as temporary space, many are now used as permanent classrooms (see Figure 1-8). 

Figure 1-3 

Elementary school, 

Washington, DC, 1930
AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION PROCESS 1-5

Schools built in the 1980s and 1990s assumed a wide variety of 

forms, often combining classrooms into clusters and focusing on 

providing an attractive learning environment (see Figure 1-9). 

However, demographic needs, shortage of affordable land, and 

limited funding has also resulted in instances of the adaptation of 

existing non-educational buildings into schools (see Figure 1-10).

Figure 1-5 

Compact courtyard plan, 

1960s

Figure 1-4 

Typical finger plan school, 1940s. In California, the 

access hallways would be open to the air. The crosssection diagram shows the simple and effective day 

lighting and ventilation. 
1-6 AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION PROCESS 

Figure 1-6 

Fountain Valley High School, Huntington Beach, CA, 1964 

(330 students)
AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION PROCESS 1-7

Figure 1-8 Typical modular classrooms, 1980s, still in use

Figure 1-7 

Open enclosure plan teaching area, with movable screens and storage, 

Rhode Island, 1970
1-8 AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION PROCESS 

Figure 1-10 

Private high school, Palo Alto, CA, located in a remodeled industrial 

building. Note the exterior cross bracing; the building required extensive 

retrofitting to meet school seismic requirements.

Figure 1-9 

Elementary school, Fairfield, PA, 1980s
AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION PROCESS 1-9

1.4 PRESENT SCHOOL DESIGN

As the U.S. begins a new century, there are indications that a new 

era of social, economic, and educational concerns is evolving that 

will impact school design. New statements of design principles are 

beginning to emerge, although some of the following represent 

perennial concerns:

❍ The building should provide for health, safety, and security.

❍ The learning environment should enhance teaching and 

learning and accommodate the needs of all learners.

❍ The learning environment should serve as the center of the 

community.

❍ The learning environment should result from a planning/

design process that involves all stakeholders.

❍ The learning environment should allow for flexibility and 

adaptability to changing needs.

❍ The learning environment should make effective use of all 

available resources.

These principles lead, in turn, to a number of current design principles, including:

❍ Design for protection against natural hazards

❍ Increased design attention to occupant security

❍ Careful lighting design and increased use of day lighting and 

comfort control

❍ Design for durability 

❍ Long life/loose fit approach: design for internal change and 

flexibility

❍ Design for sustainability, including energy efficiency and the 

use of “green” materials 
1-10 AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION PROCESS 

Some new schools already respond to these needs5 and, indeed, 

their originators, school districts, communities, and designers are 

among those defining the schools of the next decade. Some of 

the changes are the result of ideology and analysis; others are enforced by the effort to provide an improved learning environment 

and enhanced learning resources in an increasingly financially 

limited school construction economy. Some school districts will 

be hard pressed to provide a minimal learning environment with 

buildings of the utmost simplicity, while meeting the requirements 

for health, safety, and security.

1.5 FUTURE SCHOOL DESIGN

Schools will continue to vary widely in size; however, even in the 

suburbs, land has become scarce and expensive. New schools will 

be more compact and the sprawling one-story campus will become 

less common (see Figure 1-11). The desire for more supportive environments and the rejection of traditional school plans will result 

in more imaginative and often more complex layouts (see Figure 

1-12). Moreover, the move to repopulate the inner cities will result 

in the construction of even more dense and compact schools. 

However, many educational researchers believe that students improve their learning skills in smaller schools. 

Figure 1-11 West High School, Aurora, IL, 2000

5 Data provided by the National Clearinghouse for Educational Facilities, Washington, DC.

SKETCH BY: CHRIS ARNOLD
AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION PROCESS 1-11

Figure1-12 

Elementary school, Oxnard, CA, 2000

SKETCH BY: CHRIS ARNOLD

Although small schools may be economically unrealistic, methods of organization 

are being explored that provide some of the 

benefits of small size within a large physical 

complex. Some schools are organized into 

“learning academies” for each grade, with 

classrooms that can expand and contract, 

and other activity rooms of various sizes. 

Other researchers believe that the conventional 

library will disappear. The trend in many new 

schools is for the library to take the form of a 

multi-media center and material collections, 

including laptop computers, that are distributed 

from mobile units to “classroom clusters.” 

Schools are increasingly seen as community 

resources that go beyond the educational functions. Adult education and community events 

now take place on evenings, weekends, and 

throughout the traditional vacation periods; 

therefore, the school day and week have been expanded. These 

uses are seen as ways of finding affordable methods of enhancing 

community service resources by ensuring that a facility’s utilization is maximized.

Indications are that the school building will probably increase in 

importance to the community, as its roles expand beyond that of 

merely providing a K-12 education for students during a school 

year. At the same time, modern technology means that today’s 

schools, already far more complex than the relatively simple 

buildings of a few decades ago, will tend to be more fragile and 

consequently more vulnerable to nature’s and society’s threats unless special attention is paid to their design and construction.

The natural hazards will remain: earthquakes and tornadoes will 

continue to be, for some locations, a source of worry and fear. 

Besides protecting their occupants, schools in earthquake-prone 
1-12 AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION PROCESS 

regions are often used as post-earthquake shelters. In California, 

this is particularly appropriate because the State’s Field Act, enacted in 1933, following the Long Beach earthquake, requires that 

public schools be designed by a licensed architect or engineer, 

their plans checked, and the construction on site inspected by 

staff of the Department of State of Architecture. Elsewhere, floods 

and high winds are a familiar threat that also must be addressed 

by knowledgeable design and good construction practice. Schools, 

or designated areas within them, located in hurricane- and tornado-prone areas are increasingly being constructed to provide 

shelter for the occupants.

1.6 THE DESIGN AND CONSTRUCTION 

PROCESS

Regardless of the size of a school construction program, certain 

steps are necessary and certain procedures must be followed. 

These will vary greatly in scope between the design of a small elementary school and the development of a multi-school program 

of new and remedial construction. Review and regulation procedures by outside agencies will also vary. Internal district decisions 

as to the design and construction process (e.g., conventional architect design and competitive construction bid, design/build or 

construction manager) will affect the scope and timing of some of 

the activities.

However, regardless of the size and scope of the project, the following steps should be taken; for a small project, they may entail 

relatively informal meetings among a few district staff, the school 

board, and others; for a large program, formal procedures must 

be established. These steps are summarized in a flow chart (see 

Figure 1-13) that follows this listing.

❍ Conduct an in-house assessment of the educational needs, 

with the assistance of a public education committee and 

consultants. Public committees continue throughout the 

programming and design process, acquiring specialist 

members as necessary at different stages for a large program.
AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION PROCESS 1-13

❍ Determine the size and scope of the proposed program. (In 

a small district, an architect may be employed to assist the 

school district with this task, who may later become the design 

architect).

❍ Conduct an assessment of the site needs to determine the size 

and availability of sites (and lease/purchase as necessary).

❍ Develop educational specifications, both in-house and/or 

consultants.

❍ Conduct an assessment of financial needs. 

❍ Identify financial resources, including alternative sources of 

funding (e.g., state and federal programs, local taxes, bond 

issues).

❍ Ensure funding (e.g., pass bond issue).

❍ Appoint a district building program management staff 

(appointed officials or a committee). 

❍ Determine the design and construction process (i.e., 

conventional design and bid, design/build or construction 

management).

❍ Select and hire architects and other special design consultants 

or design/build team members; the timing of hiring will vary, 

depending on number of projects, whether programming is 

involved, and other variables.

❍ Develop building programs, including building size, room 

size, equipment, and environmental requirements; this may 

be done in-house and/or architects or independent program 

consultants may assist. 

❍ Appoint the district staff and public stakeholders committee 

for the design phase. 

❍ Develop designs (architects), together with cost estimates. 

Hold public meetings with architects and encourage public 

input into the design, together with district progress reviews.

❍ Design completion, district review of contract documents.
1-14 AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION PROCESS 

❍ Submit construction documents to the district and any 

permitting agencies for review and approval.

❍ Submit documents to building department and other 

required agencies.

❍ Select the contractor (bidding) or finalize design/build or 

construction management contracts.

❍ School construction.

❍ School district administration of construction contract.

❍ Observation by architect and inspection as required.

❍ School completed by contractor

❍ School inspected and accepted by architect.

❍ School inspected and accepted by school district.

❍ School commissioned and occupied. 

The sequence of the above steps may vary, depending on the 

complexity of the program; some steps may be implemented simultaneously.

Figure 1-13 shows a flow chart of this typical process. Also shown 

(in the five boxes to the right) are specific activities related to 

design for multihazards and how these fit into the general construction process.
AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION PROCESS 1-15

Figure 1-13 The design and construction process flow chart
1-16 AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION PROCESS 

1.7 SCHOOL DESIGN AND CONSTRUCTION 

1.7.1 Structure

The structure provides support for all the elements of a building 

and ensures that the building can sustain all the loads and forces 

that it will encounter during its life. Often concealed behind 

ceilings, exterior cladding, and decorative facing materials, the 

structure plays a critical role in providing a safe and secure school 

building. 

Because of the relatively small size of most school buildings and 

the simplicity of design of the traditional school, with numerous 

internal walls, structural design is relatively simple and a well designed and constructed school should not collapse unless struck 

by a severe tornado or terrorist.

Most suburban schools built in the last few decades are typically 

one or two stories in height, with light steel frames or mixed 

structures of steel and wood frames and also with some concrete 

or concrete masonry walls. Except in the western states, and 

the Atlantic and Gulf coasts, concrete masonry walls may have 

nominal or no steel reinforcing. Reinforced masonry perimeter 

and/or interior classroom separation walls sometimes are used 

as shear walls to provide lateral support. First floors are generally 

concrete slab-on-grade.

Many schools may have long-span gymnasiums or assembly 

spaces, using glued-laminated wood beams, steel trusses, or 

precast reinforced concrete tees or double tees. In these long 

span structures, large diaphragm and wind uplift forces must be 

transmitted to the perimeter walls or frames and the design and 

construction of wall/roof connections are critical. 

Typical prefabricated teaching spaces consist of classroom-sized 

wood frame boxes, are air-conditioned where necessary, and generally have minimally adequate lighting and electrical services. 

They provide an economical way of solving a problem, but rows 

of prefabricated classroom boxes do not provide an appropriate 
AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION PROCESS 1-17

long-term learning and social environment. Also, they are typically less resistant to natural hazards.

Inner city schools may be three or four stories in height and are 

often built on congested sites. Structurally, they are usually constructed of reinforced masonry, reinforced concrete, and/or steel 

frames, and sometimes are a mix of these types of systems.

Older structures (i.e., pre-World War II) often had unreinforced 

masonry walls with wood floors and roof structures. Another 

common type was a lightly reinforced concrete frame infilled 

with hollow tile or masonry for walls, together with a wood floor 

and roof structure. Small schools were often of wood frame 

construction throughout, and basements and crawl spaces were 

common in these structures. Older structures are particularly 

vulnerable to natural hazards. Unreinforced masonry structures 

have performed very poorly in earthquakes and high winds, as 

have older reinforced concrete frames with infill. Older wood 

frame structures are often deficient in their design and construction detailing and are frequently weakened by insect attack or 

dry rot. 

1.7.2 Nonstructural Systems and Components

Nonstructural components and systems comprise architectural components such as ceilings and partitions, mechanical, 

plumbing, and electrical items that provide utilities and services 

to the building and cladding and roofing that provide weather 

protection and insulation.

A wide variety of exterior cladding materials are used for schools. 

The most common materials include brick or concrete masonry, 

stucco on metal or wood stud frame walls, exterior insulation 

finish systems (EIFS), and various natural and synthetic sidings 

on wood frame structures. Metal or stucco faced insulated panels 

are also used. Metal and glass curtain walls are used infrequently, 

generally in an urban setting. 
1-18 AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION PROCESS 

Newer schools usually have suspended grid ceilings that support 

light acoustic panels and inset lighting fixtures. Pendant fixtures 

are also used, in the form of rows of linear fluorescent fixtures or 

single high intensity (HID) fixtures. The latter are often large in 

size when used in assembly spaces or gymnasiums. Incandescent 

fixtures may still be found in older school buildings, but are a 

source of high energy use and should be replaced.

Non-load bearing partitions are often of hollow tile or concrete 

masonry: however, especially in the western states, partitions are 

of gypsum board over wood or metal framing, although concrete 

masonry or tile may be used in restrooms or other service areas. 

School mechanical systems are relatively simple. Older schools 

and some new ones employ perimeter hot water heating together with natural ventilation or forced air. Very old schools 

may still employ steam heating, but most of these systems should 

have been replaced by hydronic systems. Newer schools, particularly when large, often employ forced air heating, ventilating, 

and cooling systems. Concern for energy conservation has resulted in the use of innovative systems, including a return to the 

use of natural ventilation and day lighting. 

Plumbing tends to be concentrated in restroom areas, although 

science, art spaces, and school kitchens require more complex 

plumbing services. Specialized plumbing will also be found in 

mechanical/boiler rooms, the water service and fire protection 

service entrances, and domestic water heaters.

Electrical services have become increasingly complex with the 

need for ready access to power and communications services. 

The trend in communications devices to become wireless 

may serve to slightly reduce the extent of hard wired communications. Fire alarm and security services, however, require 

increasingly extensive electrical and electronic services.

Fixed classroom desks and teachers units have been replaced 

by lighter mobile furniture. Libraries still require extensive 
AN OVERVIEW OF THE SCHOOL DESIGN AND CONSTRUCTION PROCESS 1-19

shelving, although ready access to the internet may tend to reduce the use of hard-copy materials. 

Some special spaces, such as science labs, shop, and art rooms, 

need storage for hazardous chemicals and operate heavy equipment, and are vulnerable to earthquake damage. Music spaces 

and gymnasiums all have special equipment and storage needs, 

some of which would be costly to replace in the event of damage.

DESIGNING FOR PERFORMANCE 2

DESIGNING FOR PERFORMANCE 2-1

2.1 INTRODUCTION

T his chapter introduces a performance-based design 

process that is recommended for adoption by a school 

district starting a program of school construction, 

addition, or repair. The principles of performance-based design 

can be applied to the design of a single school, of any size, or to 

a school construction plan for a large school district launching a 

major program. 

Performance-based design seeks to augment current code approaches rather than replacing them. However, there is a 

significant drive to introduce performance-based codes and, 

particularly in the field of fire safety, performance-based codes 

are now used for many applications. In the natural hazards area, 

although performance-based design is well developed for seismic 

design, prescriptive approaches are still typical for floods and 

high winds. A sound multihazard design approach should provide 

an impetus to adopt a performance-based philosophy for design 

against risk. 

2.2 DEFINITIONS OF PERFORMANCE-BASED 

DESIGN

Performance-based design is an evolving concept. The term as 

currently used has multiple definitions and three are presented 

below:

❍ A design approach that meets the life safety and building 

performance intents of the traditional code while providing 

designers and building officials with a more systematic way 

to evaluate alternative design options currently available in 

codes. In this regard, performance-based design facilitates 

innovation and makes it easier for designers to propose new 

building systems not covered by existing code provisions.
2-2 DESIGNING FOR PERFORMANCE 

❍ A design approach that identifies and selects a performance 

level from several performance level options. Some provisions 

in the current version of the International Building Code 

(IBC) are sometimes called performance-based because they 

incorporate distinctions between performance goals for different building uses. These performance options are conceived 

to achieve higher-than-code-minimum design requirements.

❍ A design approach that provides designers with tools to 

achieve specific performance objectives such that the 

performance of a structure can be reliably predicted. In 

the hazards area, this approach has been highly developed 

for seismic design although considerable research is still 

necessary to ensure the requisite reliability and predictability 

that would allow a performance-based code to be possible.

2.3 THE PRESCRIPTIVE APPROACH TO 

CODES 

The traditional approach used in building codes in the United 

States has been that of prescriptive-based codes. Prescriptivebased codes are quantitative and rely on fixed values that are 

prescribed by the codes and intended to achieve a reasonable 

level of fire and life safety as well as reasonable levels of safety 

from other hazards such as earthquakes, floods, and high winds. 

Prescriptive requirements are based on broad classifications of 

buildings and occupancies, and are typically stated in terms of 

fixed values such as travel distance, fire resistance ratings, allowable area and height, and structural design (e.g., dead loads, live 

loads, snow loads, rain loads, earthquake loads, wind loads, etc.). 

Prescriptive codes provide limited rules for addressing various 

design and construction issues (e.g., establishing limits on the allowable area and height of a building, based upon construction 

type and occupancy classification). One of the current prescriptive building codes limits the basic area of a non-combustible, 

unprotected school building to 14,500 square feet. Why are this 

building and its occupants considered reasonably safe or accept-
DESIGNING FOR PERFORMANCE 2-3

able at 14,500 square feet and unsafe or unacceptable at 15,000 

square feet? This traditional approach is assumed to provide an 

“acceptable level of risk.”

This is not to say that buildings designed and built under the prescriptive based codes are unsafe, but it is important to understand 

that the requirements in the prescriptive-based codes are judged 

to be only the minimum necessary to safeguard the public health, 

safety, and general welfare. In some instances, it may be desirable, 

appropriate, or even necessary to raise the level of safety above 

the prescribed minimums.

Under the prescriptive approach, all schools are essentially 

treated alike. Thus, the requirements for an elementary school 

with 500 students are the same as those for a high school with 500 

students, although clearly there are differences in these buildings 

due to the age of the occupants and their ability to take proper 

and appropriate action under various emergency conditions. 

Another issue involving school buildings is the use of the facility 

for purposes other than education. In many communities, school 

buildings are designated as emergency shelters to be used in the 

event of a natural or manmade disaster event. The “normal” prescriptive code approach does not address the building features 

and systems necessary for the continuity of service required for 

an emergency shelter (for security, flooding, high wind, or hazardous material release issues).

How can the issues such as these and others be addressed? An innovative procedure that is becoming increasingly adopted is the 

use of a performance-based approach to improve or supplement 

the prescriptive requirements.

2.4 THE PERFORMANCE-BASED APPROACH

Although having detailed requirements for “performance” is 

relatively new to the building and fire codes used in the United 

States, the concept is not. The various “prescriptive” building, 
2-4 DESIGNING FOR PERFORMANCE 

fire, and life safety codes have all contained provisions for what 

was known as “alternative methods and materials” or “equivalencies.” These code provisions allow for the use of methods, 

equipment, or materials not specified or prescribed in the code 

provided the alternative is approved by the code official. It is 

under these provisions of the traditional codes that the performance-based design approach can be undertaken.

Under the concept of an alternative method, material, or 

equivalency, the code official must approve the alternative 

or equivalency if it can be shown to be equivalent in quality, 

strength, effectiveness, fire resistance, durability, and safety. The 

proponent of the alternative method or equivalency is responsible for providing all necessary documentation to the code 

official. Based on the ability of the code official to permit alternate methods and materials in the existing prescriptive codes, 

performance-based codes simply offer the code official a system 

with which to accept alternative designs based on performance. 

In other words, this is nothing new to the code official, it is just a 

more formal way to review designs.

As mentioned previously, taking a “performance” approach 

is not new to building design because decisions based upon 

performance occur in all most every project. As an example, 

constructing corridor walls out of either gypsum board and steel 

studs or concrete masonry units (CMUs) will meet the prescriptive code requirements for a rated corridor in an educational 

occupancy. However, from a “performance” standpoint, the 

concrete masonry assembly is more desirable due to its ability to 

withstand the normal wear and tear of such occupancy. Another 

example would be the selection of the heating, ventilating, and 

air conditioning (HVAC) system. Although either rooftop units 

or central boilers/chillers might provide the requisite thermal 

performance, life-cycle cost analysis might support the choice of 

the central boiler/chiller. 

Performance-based design provides a structured way of making 

decisions that is particularly applicable to the issue of life safety 
DESIGNING FOR PERFORMANCE 2-5

and damage reduction from natural and manmade hazards. 

From a designer’s standpoint, the performance-based codes provide a more formalized system to develop, document, and submit 

alternative materials, methods, and equivalencies.

Unlike relying solely on a prescriptive code, performance-based 

design addresses an individual building’s unique aspects or uses, 

and specific and “stakeholder” needs. “Stakeholders” include 

everyone who has an interest in the successful completion of a 

school project (i.e., the school board members, responsible officials, members of the design team, the builders, the community 

at large, parents, and the code enforcement officials). The design 

team is a sub-group of the “stakeholders,” which includes individuals such as representatives of the architect, school district, and 

other pertinent consultants.

It is critical to the proper development, approval, and implementation of any performance-based design for all of the stakeholders 

to be actively involved in the process. Because the stakeholders 

establish the acceptable level of risk, it is crucial that all stakeholders be involved in the project from the earliest stages. It is 

also important that the stakeholders realize that an incident in a 

school facility can be measured in more ways than just monetary. 

The loss of a school facility for any reason can have organizational, legal, political, social, and psychological impacts. 

The performance-based procedure provides the basis for the development and selection of design options, based upon the needs 

of the specific project, to augment the broad occupancy classification requirements. The approach structures a comparison of 

safety levels provided by various alternative designs, and also provides a mechanism for determining what level of safety, at what 

cost, is acceptable to the stakeholders. Performance-based design 

aims at property protection and life safety strategies in which the 

systems are integrated, rather than designed in isolation.
2-6 DESIGNING FOR PERFORMANCE 

2.5 HAZARD, RISK, AND PROBABILITY

But what about “risk”? We often use the terms “hazard” and “risk” 

interchangeably. However, in the performance-based design environment, this substitution is incorrect. The definitions of these two 

words are distinctly different when assessing various challenges, 

and they must be used in the correct context when working with 

stakeholders, especially those not familiar with the terms.

No one should confuse “hazard” or “risk” with “safety.” “Safe” is 

a subjective condition that everyone views differently. Society establishes what it considers to be “safe” through a process of legal 

documents: both laws and court interpretations of them. Is a 

building that meets the prescriptive code requirements “safe?” Are 

you “safe” when you occupy a building that is entirely fire-resistant 

and protected by the latest in sprinklers and fire alarm technologies? “Hazard” and “risk” are recognized terms in the design, 

construction, engineering, architectural, and scientific worlds; 

“safe” is not.

The stakeholders must properly and thoroughly evaluate the risk 

or probability of a hazard event occurring in the performance designed facility. The basic questions they should ask are:

❍ What events are anticipated?

❍ What level of loss/damage/injury/death is acceptable?

❍ How often might this happen?

As they ask themselves these questions, and develop the variety 

of scenarios to which to apply them, the stakeholders must remember that obtaining consensus on acceptable levels of risk is 

essential to the successful outcome of the project.

Risk analysis incorporates the likelihood of a specific event 

and the severity of the outcome. This process combines both 

the severity and the probability of all relevant hazard loss scenarios. Remember that it is the intent of a performance-based 

code to establish the acceptable or tolerable level of risk. The 
DESIGNING FOR PERFORMANCE 2-7

overall analysis must consider not only the frequency of an 

events’ occurrence, but the effectiveness and reliability of the 

entire building as a system. Risk analysis provides a quantitative 

measure of the risk. It also can establish the basis for evaluating 

acceptable losses and selecting appropriate designs.

Risk managers use two different evaluative methods in risk and 

hazard analysis: deterministic and probabilistic.

Deterministic analysis relies on the laws of physics and chemistry, 

or on correlations developed through experience or testing, 

to predict the outcome of a particular hazard scenario. In the 

deterministic approach, one or more possible designs can be 

developed that represent the worst possible credible events in a 

specific building. In this approach, the frequency of possible occurrences need not be evaluated.

Probabilistic analysis evaluates the statistical likelihood that a specific event will occur and what losses and consequences will result. 

This approach may use both statistics and historical information.

History from events involving similar buildings or equipment, 

building contents, or other items can be considered. The frequency of occurrences of a particular type of event is evaluated.

Any risk analysis method must anticipate a certain level of “uncertainty.” Uncertainty describes those factors or circumstances that, 

if altered, affect the desired outcome.

Risk is the product of potential consequences and the expected 

frequency of occurrence. Consequences may include death, 

serious injury, or time lost from work, the extent of structural 

damage, monetary loss, interruption of use, or environmental impact. The occurrence frequency may be an estimate of how often 

the project loss might occur. 

Risk binning is an alternative to the more classic risk analysis, 

and is considered to be much simpler. Instead of identifying and 
2-8 DESIGNING FOR PERFORMANCE 

evaluating every possible hazard, it quantifies (measures) the consequences of the most severe events and matches them with an 

approximate event frequency. The concept is based on the idea 

that, if one prepares for the worst-case scenario, lesser damaging 

events will result in favorable outcomes.

For each type of event, the maximum consequence must be established. Consequences may include death or serious injury; or 

massive structural damage, absolute loss of production, severe 

environmental damage, or total business interruption. The consequences should represent the largest realistic event of each type.

The provisions of the International Code Council (ICC) Performance Code for Buildings and Facilities (2003 edition) describe this 

as the “magnitude of events.” These range from small, medium, 

large, and very large. Table 2-1 shows the correlation between the 

“magnitude of events” and acceptable levels of damage

For seismic, flood, and wind events, the ICC Performance Code for 

Buildings and Facilities has established criteria for the various magnitude of events as shown in Table 2-1.

Table 2-1: ICC Performance Code Criteria for Seismic, Flood, and Wind Events

 

Events

Seismic Flood Wind

Magnitude 

of Events

Very Large 2,475 years Determined on a site-specific 

basis 125 years

Large 475 years, but not to exceed 2/3 

of the intensity of very large

Determined on a site-specific 

basis 100 years

Medium 72 years 500 years 75 years

Small 25 years 100 years 50 years
DESIGNING FOR PERFORMANCE 2-9

2.6 ACCEPTABLE RISK AND PERFORMANCE 

LEVELS 

The performance-based design process begins with establishing 

the acceptable risk and appropriate performance levels for the 

building and its systems. The basic concept of acceptable risk is 

the maximum level of damage to the building that can be tolerated, related to a realistic risk event scenario or probability. For 

each hazard, there are methods of measuring the magnitude of 

events and their probability, as well as terminology to describe 

levels of damage or performance levels. There are four performance levels, each of which addresses structural damage, 

nonstructural systems, occupant hazards, overall extent of 

damage, and hazardous materials. The types of damage that are 

defined will vary according to the type of hazard that is being 

addressed. The ICC Performance Code for Buildings and Facilities formalized four design performance levels in terms of tolerable limits 

to the building, its contents, and its occupants that apply to all 

types of hazards. These levels are as follows:

Mild Impact. At the mild impact level, there is no structural 

damage and the building is safe to occupy; injuries are minimal 

in number and minor in nature; damage to the building and 

contents is minimal in extent and minor in cost; and minimal hazardous materials are released to the environment. 

Moderate Impact. At the moderate level, there is moderate, repairable structural damage, and some delay in re-occupancy can 

be expected; injuries may be locally significant, but generally 

moderate in numbers and in nature; there is a low likelihood of 

a single life loss and very low likelihood of multiple life loss; and 

some hazardous materials are released to the environment, but 

the risk to the community is minimal.

High Impact. At the high impact level, it is expected that there 

will be significant damage to structural elements, but with no 

falling debris. Significant delays in re-occupancy can be expected. 

Nonstructural systems needed for normal building use are also 
2-10 DESIGNING FOR PERFORMANCE 

significantly damaged and inoperable. Emergency systems may be 

damaged, but remain operational. Injuries to occupants may be 

locally significant with a high risk to life, but are generally moderate in numbers and nature. There is a moderate likelihood of 

a single life loss, with a low probability of multiple life loss. Hazardous materials are released to the environment with localized 

relocation required.

Severe Impact. With severe impact, there will be substantial structural damage, and repair may not be technically possible. The 

building is not safe for re-occupancy, because re-occupancy could 

cause collapse. Nonstructural systems for normal use may be completely nonfunctional, and emergency systems may be substantially 

damaged and nonfunctional. Injuries to occupants may be high in 

number and significant in nature. Significant hazards to life may 

exist. There is a high likelihood of single life loss and a moderate 

likelihood of multiple life loss. Significant hazardous materials 

may be released to the environment, with relocation needed beyond the immediate vicinity.

2.7 CORRELATION BETWEEN PERFORMANCE 

GROUPS AND TOLERATED LEVELS OF 

DAMAGE

The provisions of the ICC Performance Code for Building and Facilities correlate the performance groups and the tolerated levels of 

damage. Table 2-2 shows this relationship. Events are classified as 

small, medium, large, or very large. Each hazard will have its own 

definitions that modify these generic magnitudes.

Building groups in the ICC Performance Code include: 

❍ Group I - Buildings that represent a low hazard to human life 

in the event of failure

❍ Group II - All buildings except Groups I, III, and IV 

❍ Group III - Buildings with a substantial hazard to human life, 
DESIGNING FOR PERFORMANCE 2-11

including schools or day care centers with a capacity greater 

than 250 

❍ Group IV - Buildings designed as essential facilities, including 

designated earthquake, hurricane, or other emergency 

shelters

Table 2-2: Performance Groups and Tolerated Levels of Damage

 Building Groups

Increasing Level of Performance (Performance Groups)

Group 1 Group II Group III Group IV

Magnitude of 

Events

Very Large (very rare) Severe Severe High Moderate

Large (rare) Severe High Moderate Mild

Medium (less frequent) High Moderate Mild Mild

Small (frequent) Moderate Mild Mild Mild

Using an elementary school with an occupant load of less than 250 

as an example (Group II), it can be seen that there is a significant 

difference in the level of performance required when the building 

is to be used as a designated emergency shelter (Group IV). These 

performance levels clearly are not addressed by the prescriptive 

code requirements.

For hazards such as earthquakes and winds, it may be desirable 

to set different performance objectives for nonstructural versus 

structural design. Although the prescriptive code may provide acceptable structural safety, it may be cost effective to spend a small 

additional amount of resources to enhance the attachment and 

bracing of key nonstructural components and provide for independent inspection of their installation. Local information on the 

characteristics of flood may suggest that it is prudent to allow an 

increased factor of safety above the expected flood elevation at 

the property. Similarly, local experience may suggest that projects 

should be designed for higher wind speeds than the code values.
2-12 DESIGNING FOR PERFORMANCE 

SOURCE: BASED ON A CHART TAKEN FROM THE SFPE GUIDE TO PERFORMANCE-BASED FIRE PROTECTION, NFPA, QUINCY, MA, 2000

Figure 2-1 Performance-based design approach flow chart 

The flow chart shown in Figure 2-1 summarizes a typical performance-based design process for a major design and construction 

program. It can be used as a checklist for a single construction 

project to structure early discussion between the stakeholders and 

the designers to establish the acceptable risk, performance goals, 

and objectives for the design.
DESIGNING FOR PERFORMANCE 2-13

 2.8 ROLES OF DESIGNERS, CODE OFFICIALS, 

AND THE SCHOOL DISTRICT 

The school district is responsible for retaining the services of the 

design professionals and for the costs of any special services, including contract or third-party reviews and inspections required 

by the code official. The district must also retain all required 

documents and reports on the premises and is required to operate 

the building in accordance with the approved design throughout 

the life-cycle of the building.

The design professional is an individual who is registered or 

licensed to practice his or her respective design profession as 

defined by the statutory requirements of the professional registration laws of the state or jurisdiction in which the project is to be 

constructed. The design professional must possess the required 

knowledge and skills to perform design analysis and verification in 

accordance with the code requirements and applicable standards 

of practice. Design professionals may include architects, civil and 

structural engineers, mechanical engineers, and fire protection 

engineers, to name only a few.

The design professionals and special experts must be able to apply 

performance requirements; provide appropriate analysis, research, 

computations, and documentation; utilize authoritative documents 

and design guides; and review (inspect) the completed construction elements to verify compliance with the prescribed design.

All design documentation must be prepared by the design professional. Required documentation includes a concept report, 

a design report, and an operations and maintenance (O&M) 

manual. The design professional must coordinate all plans and 

documents for consistency, compatibility, and completeness, and 

submit them to the code official for review and approval. 

The code official is required to perform a “knowledgeable” review of the proposed design and is permitted to use a third-party 

or peer review. When such third party or peer review is used, the 

cost for such services may be passed on to the submitter. After 
2-14 DESIGNING FOR PERFORMANCE 

the plans and specifications have been reviewed and approved, 

a permit is issued for the start of construction. During the construction process, inspections and tests must be conducted in 

accordance with the design documents, code official procedures, 

and applicable codes. Upon completion, acceptance testing must 

be undertaken prior to occupancy.

After completion of the project and acceptance testing, the design 

professional must prepare and submit to the code official documentation that verifies that all performance and prescriptive code 

provisions have been met. The code official is permitted to require 

a third-party or peer review of this documentation. After completion of construction, final inspection, and testing and submission 

of all required documentation, the code official must issue the certificate of occupancy. A temporary certificate of occupancy may be 

issued for a limited timeframe with specified conditions, provided 

that all life safety items are accepted. The code official may also require that a temporary certificate be issued for a specific period of 

time and/or be “renewable” on a periodic basis.

The school district is responsible for proper maintenance and 

operation of the building, in accordance with the O&M manual, 

throughout the life of the building. 

The school district is also responsible for periodically verifying 

compliance with the approved design at a frequency approved by 

the code official. Documents verifying that the building, facilities, 

premises, processes, and contents are in compliance with the approved design documents must be filed with the code official.

2.9 CHANGES TO A BUILDING 

DESIGNED FOR PERFORMANCE

When a building that was designed and constructed using a performance-based design is remodeled or altered, or its use changed, 

a design professional must evaluate the existing building and applicable documentation. Any change that results in an increase in 

hazard or risk must undergo a full review and evaluation of the de-
DESIGNING FOR PERFORMANCE 2-15

sign. The review and evaluation must be documented in a written 

report and submitted to the code official for review and approval. 

Such written review must be submitted to the code official even 

when the proposed changes do not exceed the original conditions. 

One area of change that can occur is in one or more of the original bounding conditions. Bounding conditions by definition are 

conditions that, if exceeded, invalidate performance-based design. 

These could be maximum allowable conditions such as fuel load 

or type and arrangement of fuel load that must be maintained 

throughout the life of a building to ensure that design parameters 

are not exceeded.

Some examples of a change in bounding conditions are:

❍ The original design assumed that the gym would be used only 

for spectator sporting events. Such an arrangement would 

present a relatively low HVAC load. The desire is to now 

use the same gym for a science fair with the display of many 

project and other related materials. The new use represents 

a much higher HVAC load than originally intended and thus 

would represent a change in bounding condition. 

❍ The building was originally designed for use as a high 

school. Characteristics of these occupants to respond to an 

emergency situation are a bounding condition. The desire 

is now to change the school to one on the elementary level. 

Because the ability of these occupants to respond to an 

emergency is different, this would represent a change in 

bounding conditions.

2.10 CURRENT PERFORMANCE-BASED 

CODES

Performance-based codes are not based on broad or generic 

classifications, but are qualitative. They establish, by a consensus 

process, acceptable or tolerable levels of hazard or risk for a variety of health, safety, and public welfare issues. Three model 
2-16 DESIGNING FOR PERFORMANCE 

codes that are currently available are the ICC Performance Code for 

Buildings and Facilities, the National Fire Protection Association 

(NFPA) 101 Life Safety Code, and the NFPA 5000 Building Code. Any 

one or a combination of these documents would be appropriate 

for use in a performance-based design.

Although the ICC Performance Code for Buildings and Facilities addresses all types of building issues, the provisions of the NFPA 101 

Life Safety Code, “Performance-based Option,” address only those 

issues related to “life safety systems.” The provisions of the NFPA 

5000 Building Code apply not only to life safety issues, but to all traditional “building code” issues as well.

This design approach is based on a life safety evaluation, which is 

a written review dealing with the adequacy of life safety features 

relative to fire, storm, collapse, crowd behavior, and other related 

safety considerations. 

The performance-based design must be prepared by a person with 

qualifications acceptable to the code official. The code official is 

permitted to require an approved, independent third-party review 

of the proposed design and provide an evaluation of the design to 

the code official. All data sources are required to be identified and 

documented. The code official is empowered to make the final determination as to whether the performance objectives are met.

Design specifications and other conditions used in the performance-based design must be both clearly stated and shown to be 

realistic and sustainable. The characteristics of the building or its 

contents, equipment, or operations that are not inherent in the 

design specifications, but that can affect occupant behavior or the 

rate of hazard development, are required to be explicitly identified. The anticipated or expected performance of a fire protection 

system and building features must also be documented. 

In addition, the selection of the occupant characteristics must be 

approved by the code official and must reflect the expected population of building users. Response characteristics of the occupants 
DESIGNING FOR PERFORMANCE 2-17

should include their sensibility (sensory awareness), reactivity, mobility, and susceptibility. Sources of data for these characteristics 

must be documented. It must also be assumed that, in every normally occupied room or area, at least one person will be located at 

the most remote point from the exits. The design must also reflect 

the maximum number of people that every occupied room or 

area is expected to contain.

In those instances where the ability of trained employees (occupants) is part of the overall performance design concept, the 

number of employees, and their training and abilities should be 

identified and documented.

2.11 THE O&M MANUAL AND THE 

OCCUPANTS’ HANDBOOK

The last critical component of the performance-based design process is the O&M manual. The design professional is responsible 

for developing this important document, which can be described 

as an owners manual for the building and all of its systems. This 

document should clearly establish the requirement that the school 

official must ensure that all components of the performancebased design are in place, operational, and properly maintained 

for the entire life-cycle of the building. 

The ICC Performance Code for Buildings and Facilities, the NFPA 

101 Life Safety Code, and the NFPA 5000 Building Code all provide 

for the continued use and maintenance of a performance-based 

design facility. Each building or facility designed and constructed 

using a performance-based design relies on certain conditions remaining stable throughout the life of the building. 

The O&M manual documents agreements with stakeholders and 

clearly states that the building owner must ensure that the components of the performance-based design remain in place and in 

proper operating condition. The manual provides instructions 

that place restrictions on the building operations, and communicates to the building tenants and occupants the limits of 
2-18 DESIGNING FOR PERFORMANCE 

building use and their responsibilities. It also provides a guide to 

renovation and documents what actions are to be taken if a fire 

protection system is impaired or removed. The importance of the 

O&M manual cannot be understated. It is the glue that holds the 

on-going use of the building together.

The O&M manual must be submitted with the final design documents, and all of the stakeholders must agree on its contents. 

The manual should contain the requirements for the testing, inspection, and maintenance of all systems; outline restrictions on 

building operations; and provide guidelines on how to address 

any changes in occupancy or use. 

This manual also must be made part of the legal documents of the 

property so that they are transferred with any change in ownership. The O&M manual should include:

❍ Descriptions of the commissioning requirements of all fire 

protection systems

❍ Identification of all subsystems

❍ Descriptions of all inspections, testing, and maintenance 

procedures and schedules

❍ Information on emergency electrical power systems

❍ Details on building operations (e.g., critical fuels loads, 

sprinkler design requirements, building use and occupancy, 

reliability and maintenance of fire protection systems)

❍ Details of the maintenance plans for critical design 

components

❍ Qualifications of inspection personnel or inspectors

❍ Fee schedules for unique or third party inspections required 

by the code official and provisions of changes to the fee 

schedules 

❍ Requirements to be followed if any fire protection system is 

impaired or out of service
DESIGNING FOR PERFORMANCE 2-19

❍ Testing criteria for initial acceptance, including pass/fail 

criteria, inspection/testing schedules, periodic testing criteria, 

and recordkeeping requirements

In addition, the manual should spell out any requirements or 

restrictions, such as storage height, commodity type, or fire protection system modifications. 

The O&M manual should also contain the occupants’ handbook. In the case of school occupancies, this is the portion of the 

O&M manual that would be provided to the faculty and support 

staff. Less technical than the O&M manual and similar to the 

handbook that comes with a new automobile, this publication 

informs all occupants of the specific building about the design 

features of the building and its equipment, as well as the occupants’ responsibilities. It also serves as a guide for renovations 

and changes to workspaces. In addition, the occupants’ handbook should provide details for the development and submittal 

of modifications for review and approval by the Authority Having 

Jurisdiction (AHJ), building owner, insurance carrier, or other 

appropriate stakeholders. 

2.12 PERFORMANCE-BASED DESIGN FOR 

NATURAL HAZARDS

As noted in Section 2.4, a performance-based approach to 

building design is not new, because decisions based on performance occur frequently in almost any project. What is new is the 

attempt to formalize a decision-making process related to expected 

performance and, ultimately to develop performance-based codes 

to regulate building design and construction.

In the natural hazards area, “performance” is used to signify a 

level of damage or load. This, in itself, represents a major change 

in perception, because the building owner or occupant generally 

believes that adherence to building codes provides a safe environment and anticipated degrees of damage are not a normal source 

of conversation between an architect and owner, or even an archi-
2-20 DESIGNING FOR PERFORMANCE 

tect and his engineer. Earthquake experience in recent years has 

forced recognition that damage (sometimes severe) will occur in a 

building designed in accord with the code.

The theory and practice of performance-based design currently 

is most advanced in seismic design and virtually non-existent in 

design for floods and high winds. Advanced seismic engineering 

practitioners have, for some time, recognized several performance 

objectives in relation to owner’s needs, and have used them as a 

basis for establishing design parameters. These objectives, or performance levels, can be simply stated as follows:

❍ Level 1: The building is essentially undamaged and can be 

immediately operational.

❍ Level 2: The building is damaged, and needs some repairs, 

but can remain occupied and be functional after minor 

repairs (of a nonstructural nature) are complete.

❍ Level 3: The building is both structurally and nonstructurally 

damaged, but the threat to life is minimal and occupant 

injuries should be minor and few.

❍ Level 4: The building is severely damaged and will probably 

have to be demolished; it has not collapsed, although there is 

some likelihood of occupant injury.

In this spectrum, the code conforming building is fairly far down 

the scale (at Level 3) and many private and public owners are 

prepared to pay more to achieve a higher level of performance. A 

hospital should achieve at least Level 2, and preferably Level 1. A 

high-tech manufacturing plant might desire to achieve the same 

level, because of the high value of its contents and the business 

losses if the plant must shut down production. The owner of a 

warehouse that houses a modest and easily replaced commercial 

inventory, with very few occasional occupants, might opt for the 

economies of Level 4.

In the last decade or so, this informal pragmatic approach to 

performance-based seismic design has become formalized; the 
DESIGNING FOR PERFORMANCE 2-21

performance levels have been named and carefully defined. 

Detailed observation of damaged buildings, together with advances in materials science, experimental research, and analytical 

methods, have led to much more sophisticated understanding of 

building response and have enabled engineers predict more reliably how a structure will behave under various levels of shaking. 

This prediction is still far from a guarantee, but it has a scientific 

and engineering basis that was non-existent even 2 decades ago. 

Meanwhile, extensive studies of all aspects of performance-based 

seismic design are underway around the country, largely sponsored by FEMA and the National Science Foundation.

The same degree of research and development activity does not, 

however, apply to design for floods and high winds. One reason is 

that these fields have not had the same sophisticated (and fairly 

expensive) research support that the seismic community has 

enjoyed. Before performance-based design for floods and winds 

can become a reality, a solid research base must be established. 

The kind of research would be different from that of seismic 

engineering; the engineering problems are much simpler, but 

research into simulating the probabilities and effects of floods 

and winds could yield rich rewards. The objective is to reduce the 

uncertainties associated with these hazards, thus avoiding wasted 

money and resources. Wind design could benefit from materials 

and component research to improve exterior envelope design and 

construction: at present, many of the available protective methods 

are labor intensive in the most primitive way, often using only 

hammers, nails, and stapling guns.

If design for performance against floods and high winds is to approach the sophistication of seismic performance-based design, 

a new approach to thinking about buildings subjected to floods 

and winds is necessary, paralleling the new thinking that has 

occurred around buildings subjected to earthquakes. When engineers began to think about buildings from the owners’ viewpoint, 

and the different ways in which buildings were occupied, it became clear that a seismic code that focused only on methods and 

technical design criteria instead of results was not responding to 
2-22 DESIGNING FOR PERFORMANCE 

owners’ (and society’s) needs. Performance-based seismic design 

is still in its infancy, and much research needs to be done, but the 

essential shift in thinking has occurred. 

Performance-based design is not proposed as an immediate 

substitute for design to traditional codes. Rather, it is seen as an 

opportunity for enhancement and the tailoring of the design 

to match the objectives of the community. Design to the code 

remains as the minimum baseline to ensure safety for school occupants, but the special importance to our society of protecting 

the school population suggests that design to a generic code minimum is not sufficient.

To achieve a building code that regulates performance rather than 

easily inspected design construction methods will not be easy, but 

ultimately one can expect to see a rational mix of performance 

and prescription in the regulatory mix. That shift took place in 

advanced industries (e.g., airplane design) a few decades ago, and 

airplanes are now habitually designed to stringent performance requirements, specified by the military or the airline companies.

Designers and owners of buildings in flood or high wind-prone regions need to begin to think in terms of a few basic objectives:

❍ Can the real probabilities and frequencies of events during 

the useful life of the building be defined with a useful degree 

of accuracy?

❍ Can the extent and kinds of damage (if any) that can be 

tolerated be defined?

❍ Are there ways (if any) in which this acceptable level can be 

achieved?

❍ Are there alternative levels of performance that can be 

achieved and how much do they cost over the lifetime/

ownership of the building?

❍ Are these levels below, at, or above design to code enforced 

criteria?
DESIGNING FOR PERFORMANCE 2-23

Serious thought about these basic issues by all the stakeholders is 

the beginning of design for performance.

2.12.1 Performance-based Seismic Design

As discussed in Section 2-12, procedures for the application of 

performance-based design seismic design are well advanced. 

However the procedures are still evolving and issues such as terminology, analytical methods, and achieving reliable performance 

prediction are still subject of much research and development. 

This section outlines the general approaches that are current in 

performance-based seismic design; considerable refinement of the 

approaches and procedures that are outlined herein are expected 

to occur in the next few years.

Determining Acceptable Risk. The performance-based design 

procedure starts with the definition of acceptable risk. Prior to 

inception of design work for a new or retrofitted school building, 

discussions should be initiated between the design team, the 

school district, and community representatives to explain the level 

of seismic performance that will be achieved by conformance to 

the code, and other possible performance options that may be 

available. In these discussions, “seismic performance” refers to the 

extent of damage and loss that is likely to occur in earthquakes of 

differing magnitudes. These discussions focus on ensuring that all 

parties understand that “earthquake" or damage-free performance 

is not possible, and compromises must be made between seismic 

performance, cost, and design for learning. “Acceptable risk” 

refers to the extent and types of damage and loss that the school 

officials and community can tolerate. Clearly, avoidance of casualties is of the highest priority, but what are the priorities for issues 

such as damage to the building’s structure, nonstructural components, and systems and contents?

The discussion of acceptable risk begins with determining the answer to the following question: If the building is designed strictly 

to the minimum code requirements, are the damage and loss that 

might occur in the design level earthquake acceptable? If the an-
2-24 DESIGNING FOR PERFORMANCE 

swer to this question is positive, an implicit level of acceptable risk 

has been set and design can proceed. If the answer is negative or 

undecided, the following should be addressed:

❍ What lesser extent and types of damage can be accepted?

❍ What are the implications for long-term costs and benefits 

over the life of the school building?

❍ Is the desired performance level affordable within the firstcost resources of the district (minimum code requirements 

must always be provided)?

Issues of uncertainty must also be made clear. It should be noted 

that the degree of uncertainty in predicting performance will be 

dependent on the existing school design in addition to the application of code requirements. The design team for a new building 

has control over this issue; however, for a retrofit, some of the existing school characteristics may be less than desirable. 

A new design in which key parameters of good seismic design 

are provided (i.e., continuous load path, structural redundancy, 

symmetry in plan and section, short spans, and well designed 

nonstructural connections and bracing) will be more economical 

and more predictable in performance than a design in which 

these characteristics are not present. (The simple concept design 

shown in the How Buildings Resist Earthquakes illustration in Section 4.6.1 represents an “optima” seismic design that incorporates 

these features.)

Discussions of these issues should lead to a formal conclusion 

on performance objectives that then serve as a target for the designers, but it is the school district representatives who must make 

the final performance objective decision. The implications of this 

decision must be fully understood and it is the responsibility of the 

design team to provide necessary information, to the extent that it 

is available.
DESIGNING FOR PERFORMANCE 2-25

Traditionally, the architect has been the source of all design information for the school authorities but, due to the technical 

sophistication of performance-based design, the structural engineer will probably be consulted. On large projects, the key 

consultants may be involved in early meetings, particularly when 

the school district is represented by a facilities manager or other 

technical staff. In these instances, the district’s professional staff 

may be expected to be able to discuss the project on equal terms 

with the design team. Whether all parties are familiar with the 

language of performance-based seismic design may have significant impact on the extent to which seismic performance issues 

can be a subject for useful discussion and decision-making. 

If community representatives or committees, whose technical expertise may be more limited, are involved, the design team should 

try to ensure that the issues are understood.

For most school districts and communities, the discussion of acceptable risk will be an entirely new kind of discussion and the 

language of seismic performance may be unfamiliar. Historically, it 

has not been common practice to initiate a discussion of damage 

tolerance for a new project. The seismic expectations checklist in 

Table 2-3 provides a basis for these discussions. The checklist takes 

the form of a matrix of design expectations that can assist design 

team members, the school district, and the community to agree 

on seismic performance goals that are reasonably in line with the 

available resources. Agreement on such goals and expectations 

can help achieve a desired level of performance and limit later 

surprises due to unexpected earthquake damage. Such performance objectives statements might properly be part of a project’s 

building program and serve as the basis for a performance-based 

design procedure.

The checklist can be completed or used merely as a basis of discussion. The intent is for the school district to arrive at a seismic 

performance objective that is understood and approved, both as 

to its opportunities and its limitations. 
2-26 DESIGNING FOR PERFORMANCE 

Table 2-3: Seismic Expectations Checklist 

Earthquake Performance of Structural Systems

Damage

Earthquake Magnitude Severe: No life threat or 

collapse

High: repairable damage; 

building not usable 

Moderate: repairable 

damage; building usable

Mild: no significant 

damage

Low-Moderate

Moderate-Large

Large

Earthquake Performance of Nonstructural Components and Systems

Damage

Earthquake Magnitude Severe: No life threat or 

system failures

High: Repairable damage; 

building not usable 

Moderate: Repairable 

damage; building usable 

Mild: No significant 

damage

Low-Moderate

Moderate-Large

Large

Functional Disruption: Structural and Nonstructural

Time to Reoccupy

Earthquake Magnitude 6 months plus up to 3 months up to 2 weeks Immediate

Low-Moderate

Moderate-Large

Large

Notes: Earthquakes:

Low-Moderate: up to Magnitude 6.5 on the Richter scale

Moderate-Large: Magnitude 6.5 - 7.5 on the Richter scale

Large: Magnitude 7.5 plus on the Richter scale

SOURCE: (MODIFIED) ERIC ELSESSER: BUILDINGS AT RISK, AIA/ACSA COUNCIL ON ARCHITECTURAL RESEARCH, WASHINGTON, DC, 1992
DESIGNING FOR PERFORMANCE 2-27

The above classifications may be modified by poor soil conditions or specific seismological forecasts. Note that this table adds 

a short description to the four damage level categories identified 

in the ICC Performance Code for Buildings and Facilities outlined in 

Section 2.12.

Table 2-4 shows the expected overall and nonstructural damage 

for the four building performance levels defined in FEMA 273, 

NEHRP Guidelines for the Seismic Rehabilitation of Buildings. These 

performance levels are developed versions of the four general 

performance levels described on page 2-20. The bottom row relates the damage levels to those expected for a building designed 

to a conventional code. FEMA 273 contains six such tables that 

show expected damage to vertical and horizontal structural 

elements; architectural, mechanical, electrical, and plumbing 

components; and building contents. These expectations refer 

to a building designed using the appropriate analytical tools 

available in FEMA 273, which provides the necessary methods 

of analysis and detailing to achieve these performance levels for 

high, moderate, and low earthquake intensity regions. Some of 

the terminology in these tables may be expected to change as a 

result of studies now underway.
2-28 DESIGNING FOR PERFORMANCE 

Overall Damage Level 4 

(Severe)

Level 3 

(Moderate)

Level 2 

(Light)

Level 1 

(Very Light)

General Little residual stiffness 

and strength, but load 

bearing columns and 

walls function. Large 

permanent drifts. Some 

exits blocked. Infills and 

unbraced parapets failed 

or at incipient failure. 

Building is near collapse.

Some residual strength 

and stiffness left in all 

stories. Gravity-load 

bearing elements 

function. No out-ofplane failure of walls 

or tipping of parapets. 

Some permanent drift. 

Damage to partitions. 

Building may be beyond 

economical repair.

No permanent drift. 

Structure substantially 

retains original strength 

and stiffness. Minor 

cracking of facades, 

partitions, and ceilings 

as well as structural 

elements. Elevators 

can be restarted. Fire 

protection operable.

No permanent drift. 

Structure substantially 

retains original strength 

and stiffness. Minor 

cracking of facades, 

partitions, and ceilings 

as well as structural 

elements. All systems 

important to normal 

operation are functional.

Nonstructural 

components

Extensive damage. Falling hazards 

mitigated, but many 

architectural, mechanical, 

and electrical systems are 

damaged.

Equipment and contents 

are generally secure, but 

may not operate due to 

mechanical failure or 

lack of utilities.

Negligible damage 

occurs. Power and other 

utilities are available, 

possibly from standby 

sources.

Comparison with 

performance 

intended for 

buildings 

designed, under 

the NEHRP 

Provisions, 

for the Design 

Earthquake

Significantly more 

damage and greater risk.

Somewhat more damage 

and slightly higher risk.

Much less damage and 

lower risk.

Much less damage and 

lower risk.

Table 2-4: Damage Control and Building Performance Levels

Building Performance Levels

Collapse Prevention 

Level Life Safety Level Immediate OccupancyLevel

Operational

Level

SOURCE: NEHRP GUIDELINES FOR THE SEISMIC REHABILITATION OF BUILDINGS (FEMA 273)

Reducing Seismic Risk Through Performance-based Design. The 

general principles of performance-based design are discussed 

in earlier sections of this chapter. For seismic risk reduction, 

performance-based design starts with the recognition that some 

damage will be incurred in a severe earthquake even in a well 

designed and constructed building. Prior to the seismic design, 
DESIGNING FOR PERFORMANCE 2-29

the school districts and the design team reach agreement on the 

desired seismic performance of the building (i.e., the extent and 

type of damage that the school district can tolerate). The extent of this damage can be reduced by seismic design measures 

based on more precise analysis of the earthquake forces that the 

building will encounter, rather than relying on the simplified 

analytical methods of the current seismic code.

These more precisely estimated forces may, in some instances, 

be less than the forces determined by a simple code analysis because less allowance will need to be made for uncertainty in the 

calculations, and the seismic design and construction cost may 

be reduced. Increased protection beyond the minimum code expectations, however, will almost inevitably add to the initial cost 

of the building. The trade-off that the school district must consider is that damage reduction will probably result in design and 

construction cost increases. 

The value to the district of increased investment in seismic protective design and construction is dependent on the likelihood 

of damaging earthquakes, and some economic analysis can assist in arriving at an affordable solution with satisfactory safety 

and damage control characteristics. This implies that the cost of 

protection must be evaluated over the life of the building, rather 

than only as an item of the initial building cost. As with design 

to the current code, performance-based design starts with the 

assumption that the basic purpose of seismic design is to protect 

the building occupants from collapse and damage that may be 

life-threatening.

The performance-based design procedure uses inputs from the 

information evaluations previously described to develop designs 

that balance the desired performance levels with the available 

resources.
2-30 DESIGNING FOR PERFORMANCE 

2.12.2 Performance-based Flood Design

The performance objectives (or performance levels) for flood 

hazards can be stated as follows:

Level 1: The school building sustains no structural or nonstructural damage, emergency operations are fully functional, and the 

building can be immediately operational; the campus is not affected 

by erosion but may have minor debris and sediment deposits. 

Level 2: The school building is affected by flooding above the 

lowest floor, but damage is minimal due to shallow depths and 

short duration. Cleanup, drying, and minor repairs are required, 

especially of surface materials and affected equipment, but the 

building can be back in service in a short period of time. Site 

improvements such as bleachers and fences are damaged, and 

athletic fields are damaged by erosion and deposition of sediment and debris.

Level 3: The school building may sustain structural damage that 

requires extensive repair and partial reconstruction. If the school 

is used as a shelter, threats to occupants are minimal. Nonstructural damage to equipment and finish materials requires cleanup, 

drying, and repairs. Site improvements such as bleachers and 

fences are damaged, and athletic fields are damaged by erosion 

and deposition of sediment and debris.

Level 4: The school building is severely damaged and likely 

requires demolition or extensive structural repair. Threats to 

occupants are substantial and warning plans should prompt evacuation prior to the onset of this level of flooding. (Note: Level 4 is 

applicable to schools affected by flooding due to failure of dams, 

levees, or floodwalls.)

In addressing the question “what level of loss/damage/injury/

death is acceptable?”, an assessment of the probable magnitude 

and frequency of flood events during the life of a school is relatively straightforward. With the exception of floods caused by 
DESIGNING FOR PERFORMANCE 2-31

or exacerbated by failure of dams and levees, an examination of 

available information regarding mapped flood hazard areas, 

predicted flood elevations, and historic floods should identify 

an adequate estimation of the flooding that may affect a school 

site. It is reasonable to exceed the minimum design flood elevation and loads for essential and critical facilities, including 

schools.

Flooding of buildings rarely results in loss of life and injuries, 

although that is a likely consequence of extreme and unpredictable flooding caused by events such as dam or levee failures. 

Beyond identification of the normal design flood magnitude, 

further examination is required to identify those contributory 

hazards. State water resources agencies can identify the high 

hazard dams and significant hazard dams that are present in 

the watershed and the failure scenarios that may result in catastrophic consequences. Similarly, local agencies or authorities 

that maintain and operate levee and floodwall systems can characterize failure scenarios for protected areas. Schools located 

in areas threatened by these very low probability, high consequence events should have emergency response plans that are 

closely coordinated with the appropriate emergency management authorities.

Chapter 5 identifies a number of recommendations to exceed 

minimum flood-resistant requirements to achieve an appropriate level of protection for essential and critical facilities, 

primarily avoidance of flood hazard areas and adding a factor 

of safety to the elevation requirement. Consideration of these 

recommendations is in the spirit of performance-based design. 

To some degree, the benefits can be quantified: the National 

Flood Insurance Program’s (NFIP's) statistics on building that 

exceed the minimum requirements indicate lower damage. It is 

notable, however, that there is insufficient experience with nonresidential buildings that are exposed to extreme flooding to 

quantify the benefits.
2-32 DESIGNING FOR PERFORMANCE 

2.12.3 Performance-based High Wind and 

Tornado Design

The performance objectives (or performance levels) for the wind 

hazard can be stated as follows:

Level 1: The school building is essentially undamaged and can be 

immediately operational. 

Level 2: The school building is damaged, and needs some repairs, 

but can remain occupied and be functional after minor repairs (of 

a nonstructural nature) are complete. 

Level 3: The school building may be structurally damaged, but 

the threat to life is minimal and occupant injuries should be 

minor and few. However, nonstructural damage (i.e., the building 

envelope or rooftop equipment) is great, and the cost to repair 

the damage is significant. If rain accompanies the windstorm, 

or if rain occurs prior to execution of emergency repairs, water 

damage to the interior of the school can prohibit occupancy of all 

or a portion of the school from several weeks to several months.

Level 4: The school building is severely damaged and will probably 

have to be demolished. Significant collapsing may have occurred, 

and there is great likelihood of occupant deaths and many injuries 

unless the school has a specially designed occupant shelter. (Level 

4 is applicable to schools struck by strong or violent tornadoes. For 

other types of windstorms, Level 4 should not be reached.)

For the wind hazard, loss of life and injuries due to collapsing 

building components or wind-borne debris is quite rare. Except 

for strong and severe tornadoes, the major threat posed by high 

winds is damage to the school itself, which can be very costly to repair and may prohibit use of the school for a considerable period 

of time.

In addressing the question “what level of loss/damage/injury/

death is acceptable?”, an assessment of the probable magnitude 
DESIGNING FOR PERFORMANCE 2-33

and frequency of wind events during the life of a school is relatively straight forward. With the exception of strong and violent 

tornadoes, complying with the design procedure in ASCE 7 

should typically result in adequate estimation of the wind loads 

that a school will experience. (For strong and violent tornadoes, 

wind and wind-borne debris loads derived from FEMA 361 should 

typically provide an adequate estimation.) However, the great 

challenge with performance-based wind design is the assessment 

of the wind resistance of the building envelope and rooftop equipment and the corresponding damage susceptibility. 

Assessment of the true performance of the building envelope 

and rooftop equipment is challenging because of several unrelated factors:

❍ Analytical tools (i.e., calculations) are currently not available 

for many envelope systems and components. Because of 

the complexity of their wind load response, many envelope 

systems and components require laboratory testing, rather 

than analytical evaluation, in order to determine their loadcarrying capacity. Unfortunately, current test methods typically 

have many limitations. For example, test assemblies normally 

test unaged materials. Hence, the test may adequately indicate 

how the system will perform during the first few years of its 

life, but it may not indicate how the system will perform after 

being exposed to sunlight (which may result in heat and/or 

ultraviolet radiation induced degradation), water (which may 

degrade the system via corrosion or dry rot), or repeated 

modest wind events (which may induce fatigue failure). Also, 

tests are typically static (i.e., uniform pressure distribution), 

rather than dynamic (i.e., cyclically-induced loading). In 

addition, test assemblies are not typically subjected to winddriven water while simultaneously being subjected to designlevel wind pressures.

It is likely that finite element analysis (FEA) will eventually 

augment or replace laboratory testing, but substantial 

research is necessary before FEA becomes available for the 
2-34 DESIGNING FOR PERFORMANCE 

numerous building envelope systems from which architects 

are able to choose.

❍ Architects have traditionally given little attention to wind 

resistance of building envelopes, and mechanical engineers 

have given little attention to wind resistance of rooftop 

equipment. For those architects and engineers that try to give 

attention to envelopes and rooftop equipment, their task is 

hampered by lack of comprehensive design guides, lack of 

analytical tools and lack of realistic long-term wind resistance 

data as discussed above.

❍ Building envelopes are often constructed by several different 

trades. For example, an exterior non-load bearing wall may 

be framed by one subcontractor, another subcontractor 

may install the insulation and wall covering and another 

subcontractor may install the windows. It is challenging to 

successfully integrate these various subsystems so that winddriven water infiltration is inhibited and load-path continuity 

is maintained.

❍ Because the building envelope is exposed to weather, it is 

natural for various envelope components to lose strength over 

time. If naturally-deteriorated components are not replaced 

before they become overly weak, they can be damaged during 

storms that are well below design wind speed conditions. 

Although appropriate maintenance and repair criteria may be 

included in the O&M manual, it is often difficult to determine 

if serious corrosion, dry rot, or termite attack has occurred in 

concealed portions of the envelope. 

❍ Modifications may inadvertently weaken the resistance of the 

building envelope. For example, if a roof system incorporates 

an air retarder, and a future penetration (such as an exhaust 

fan) through the roof does not maintain the continuity of 

the air retarder at the penetration, the roof system could 

receive a sufficiently high unexpected load to result in roof 

covering damage. In this example, even though maintaining 
DESIGNING FOR PERFORMANCE 2-35

air retarder continuity should be included in the O&M 

manual, compliance with this O&M requirement could easily 

be overlooked.

Because of the great uncertainty of the true resistances of the 

building envelope and rooftop equipment on a given school, the 

level of wind and subsequent water infiltration damage that could be 

reasonably expected to result from a design-level windstorm at some 

future time is difficult to quantify at this time. With development of 

comprehensive wind design guidelines for building envelope systems 

and rooftop equipment, development of greatly enhanced test and 

analytical methods, and greater awareness on the part of designers 

and construction trades on basic design and installation techniques 

to inhibit water infiltration and practices necessary to achieve loadpath continuity, the magnitude of the uncertainty can be decreased. 

However, significant research funding is needed in order to reduce 

the uncertainties associated with the wind and water resistance of 

building envelopes and rooftop equipment.

Except for strong and violent tornadoes, schools designed and 

constructed with one of the current model building codes (and 

adequately maintained and repaired), typically present a low risk 

of casualties and injuries. However, some existing schools may 

present higher risk. For example, a glass curtain wall at a cafeteria, 

or tall unreinforced and inadequately braced CMU wall at a gym 

may be blown in or out during a strong thunderstorm. If students 

or faculty are nearby, they could be injured or killed. Or, a roof 

could blow off and injure students that are on their way to the 

buses. There is also increased risk of casualties and injuries to 

people seeking refuge in a school during a hurricane if the school 

was not originally designed for this purpose.

By considering the recommendations provided in Chapter 6, and 

implementing those that are appropriate for a given school, the 

spirit of performance-based design can be achieved, with respect 

to both casualties/injuries and building damage/interrupted use, 

for new construction, as well as existing schools. However, because 

of the limitations discussed above, it is not possible at this time to 
2-36 DESIGNING FOR PERFORMANCE

quantify the actual performance that the various enhancement 

recommendations will offer. In some cases, the recommendations may be overly conservative and, in others, they may be 

non-conservative. The recommendations will result in enhanced 

performance, but additional research is needed to quantify the 

magnitude of the enhancement.
MULTIHAZARD DESIGN 3

MULTIHAZARD DESIGN 3-1

3.1 INTRODUCTION

T his chapter compares the effects of three natural hazards 

that are the subject of this publication, in terms of their 

geographical locations, relative warning times, frequency, 

risk, and potential for damage and loss. Comparative losses are 

discussed and fire and safety considerations are presented. The 

design methods used to protect against the hazards by looking at 

the ways in which these methods reinforce or are in conflict with 

one another are compared. This is a key aspect of multihazard design because the similarities and differences in the ways in which 

hazards affect buildings and how to guard against them demand 

an integrated approach to natural hazards design. This must 

be pursued as part of a larger integrated approach to the whole 

building design problem. 

3.2 THE HAZARDS COMPARED

Natural hazards are not aberrations; they are part of the natural 

environment in which we live and in which our buildings should 

be designed to function. Therefore, it is necessary for designers to 

become knowledgeable about all natural hazards in order to gain 

an understanding of how they act and how they can be accommodated within the design process, rather than treating them as 

adversaries that the designer must reluctantly accommodate at the 

expense of more traditional design aspirations. 

This section presents a comparative sketch of the three natural 

hazards covered in this publication together with some issues 

relating to the common hazard of fire. The threat of physical attack is covered in a companion publication, FEMA 428, Primer 

to Design Safe School Projects in Case of Terrorist Attacks. A general 

understanding of all hazards is necessary in order to develop an 

integrated multihazard approach to design. It has been a tenet of 

multihazard design that design for two or more hazards may rein-
3-2 MULTIHAZARD DESIGN 

force one another, thus reducing cost and improving protection, 

but it has also been recognized that at times there may be conflicts between designs for different hazards. This section presents, 

for the first time, a systematic analysis of the reinforcements and 

conflicts between hazard protection methods. This takes the form 

of the matrices shown in Section 3.5. This section is presented to 

stimulate discussion and analysis at the outset of project design 

and to provide a format for further development and discussion of 

the issues involved. 

3.2.1 Location: Where are They?

The public perception of natural hazards is that earthquakes 

occur in California, floods in many riverine and coastal locations, 

tornadoes in the Midwest, and hurricanes along the Atlantic 

and Gulf coasts. Although there is some truth to this perception 

as it relates to the highest probabilities for each hazard, hazard 

maps show that the entire United States is vulnerable to one or 

more of the three main natural hazards: earthquakes, floods, or 

high winds. Earthquakes are predominant in the West, but also 

threaten specific regions in the Midwest, Northeast, and Southeast. The great earthquakes centered on the little town of New 

Madrid, Missouri, in 1811 and 1812 caused little damage and 

only a few casualties; a recurrence of these earthquakes would 

impact some of the most populous cities of the Midwest. The 

worst earthquake in the eastern states occurred in Charleston, 

South Carolina, in 1886; 60 people were killed and the modest 

sized city suffered the equivalent of about $25 million damage 

in today’s dollars. Riverine floods occur along rivers, largely but 

not exclusively in the Midwest, and coastal flooding is associated 

with storm surges caused by high winds. Flash floods caused by 

sudden, intense rainstorms may occur anywhere. Some of the 

worst floods in U.S. history have been caused by dam failures, 

often when rivers are swollen by flood waters. Extreme winds 

are regional (e.g., hurricanes along the Atlantic and Gulf coasts, 

the Caribbean, and the South Pacific; tornadoes typically in the 

Midwest; and downslope winds adjoining mountain ranges), but 

high winds can also occur anywhere. 
MULTIHAZARD DESIGN 3-3

Floods are fairly specific and predictable in their location, and 

effective design against floods is less a matter of design concept than of siting. A building can be located in such a way 

that floods will never be a problem; however, flood-free locations are relatively rare and our floodplains are full of existing 

buildings. Other than use of elevation, which can be reasonably 

effective, design against floods consists of a number of detailed 

measures (e.g., dry and wet floodproofing, which is discussed in 

Chapter 5 of this publication), all of which can be overwhelmed 

by flooding that exceeds the design flood. In some regions of 

the country, the designer must consider two or three natural 

hazards. In parts of California (in certain coastal and river delta 

regions), buildings are vulnerable to both floods and earthquakes, although the probability of simultaneous occurrence is 

remote. The Hawaiian Islands, Guam, the Virgin Islands, Puerto 

Rico, and parts of the East coast may all be impacted by earthquakes, floods, and high winds; although all three are lateral 

forces, they have many different characteristics that must be 

taken into design consideration.

Figures 3-1, 3-2, 3-3, and 3-4 provide four maps that show an 

overview of the incidence of earthquakes, floods, hurricanes, and 

tornadoes in the United States. Figure 3-1 shows the earthquake 

hazard for the United States; the contour lines on the map indicate the 10 percent probability of exceedance of ground motion 

accelerations within each contour area (or the “odds” that there 

is a 10 percent chance that the accelerations will be exceeded in 

a 50-year period). Maps such as this are used for seismic design 

to estimate the forces for which structures must be designed. Figures 3-2, 3-3, and 3-4 show the Presidential Disaster Declarations 

between January 1965 and November 2000 for floods, hurricanes, and tornadoes, respectively. These maps show only major 

events, and do not show all the regions where there are hazards. 

Chapters 4, 5, and 6 provide information to enable the reader to 

establish the risk for each of these hazards (earthquakes, floods, 

and high winds) in a local region, respectively.
3-4 MULTIHAZARD DESIGN 

Figure 3-2 

Presidential Disaster 

Declarations for 

floods, January 1965 

to November 2000. 

The incidence of 

declarations is shown 

by counties.

SOURCE: FEMA 386-2

Figure 3-1 

Peak accelerations (%g) with 10 percent probability of exceedance in 50 years. Color code shows %g 

for areas between contour lines. These values are used for seismic design.

SOURCE: USGS
MULTIHAZARD DESIGN 3-5

Figure 3-3 

Presidential Disaster 

Declarations for 

hurricanes, January 

1965 to November 

2000. The 

incidence of 

declarations is 

shown by counties.

SOURCE: FEMA 386-2

Figure 3-4 

Presidential Disaster 

Declarations for 

tornadoes, January 

1965 to November 

2000. The incidence 

of declarations is 

shown by counties.

SOURCE: FEMA 386-2
3-6 MULTIHAZARD DESIGN 

3.2.2 Warning: How Much Time is There?

The warning times for these hazards vary. Earthquakes are unique 

among the natural hazards because there is no warning at all, although new sensing devices can now give a few seconds warning to 

locations far from the epicenter. Floods (except flash floods) can 

be predicted so as to give hours or days of warning; hurricanes can 

be tracked for days and give several hours of warning before hitting a specific location. Tornadoes are more localized and, though 

visible, may hit a specific location almost without notice. 

Although the tornado gives warning and its approach is visible during daylight, its winds are often so strong that damage 

or destruction in its immediate vicinity is common. Hurricanes 

are tracked by the national hurricane tracking system and their 

movement is carefully and thoroughly reported. The hurricane’s 

movement along its path is slower and its size is much larger than 

a tornado, yet even then its precise route and timing cannot be 

predicted until a few hours before making landfall. 

In earthquake-prone areas that experience frequent events, such 

as California and Alaska, there is a continuous generalized prediction, but the earthquake always strikes totally without warning. 

Although much work has been done throughout the world to 

develop a scientific prediction methodology (based on characteristics such as changes in the dimensional or physical nature of 

the ground prior to an earthquake; detailed investigation of the 

geologic strata; or statistical data on the incidence of previous 

earthquakes), earthquakes must still be regarded as random 

events within a general envelope of probability.

3.2.3 Frequency: How Likely are They to 

Occur?

For all hazards, the regional probabilities are much higher 

than the local ones, and the extreme events are relatively rare 

for a given site. Inundation of floodplains in riverine areas and 

flooding of poorly protected or sited coastal locations may be 
MULTIHAZARD DESIGN 3-7

relatively frequent; the general threat along rivers occurs each 

winter and spring, and a succession of hurricanes roam the Atlantic seaboard every year, bringing the risk of extreme winds 

and storm surge. Traditionally, residents in tornado-prone areas 

retreated to their basements, but engineered safe rooms are 

now being constructed in homes, schools, and other buildings. 

Earthquakes are perhaps the most difficult to deal with, because 

of their complete lack of warning, their rarity, and their possible 

extreme consequences. Although an earthquake of a given magnitude is still, in practical terms, unpredictable, its probability of 

occurrence can safely be predicted as far higher in California or 

Alaska than in, for example, Massachusetts or Tennessee. Even 

in California, the rarity of a large earthquake is such that many 

people will not experience one in their lifetime. In less seismic 

parts of the country, one must go back several generations, or to 

folklore, for earthquake stories, but even then there is a probability of an event.

Because natural hazards are only broadly predictable, the incidence of future events can only be expressed as probabilities. This 

presents a problem because what may be perfectly rational and 

useful to a mathematician may be confusing or even counterproductive to the public and their decision-makers. The probability of 

occurrence of earthquakes, floods, and high winds is commonly 

expressed by use of the term “return period” or “mean recurrence 

interval.” This is defined as the average or mean time in years between 

the expected occurrence of an event of specified intensity.

For example, until recently, earthquake codes used as a basis 

of severity a level of shaking (an acceleration value) that corresponded to a 10 percent probability of exceedance in 50 years 

(or a probability that it would be exceeded one time in approximately 500 years, a 500-year return period). More recently, it 

has become apparent that certain areas, such as the Mississippi 

embayment area, may, in fact, be vulnerable to much larger but 

more infrequent quakes. Therefore, a new set of hazard maps 

has been produced by the United States Geological Survey 

(USGS) that shows acceleration values for a 2 percent probability 
3-8 MULTIHAZARD DESIGN 

of exceedance in 50 years (approximately 2/3 of design value). 

Designing to this level would provide real protection against a 

large earthquake. 

Values for high winds are commonly expressed in codes as a 

50-year return period, much shorter than earthquakes because 

their incidence is much more frequent. Floods are expressed 

as a 100-year return period (i.e., the “100-year flood”). To the 

public, these return periods seem very long (i.e., why would a 

business owner confronting small crises every day and large ones 

every month be worried about an event that might not occur for 

500 years - let alone 2,500 years? ). And if the return period for 

California is 500 years, would it not be another 400 years before 

something of the magnitude of the 1906 San Francisco earthquake occurs?

The problem is that these figures represent mean or average 

return periods over a very long period of time, with the result 

that the return period is often quite inaccurate in relation to the 

shorter time periods in which most of us are interested (i.e., the 

next year or the next 10 years). Because floods and high winds are 

relatively frequent, the discrepancy between the actual return period and the mean return period used in the codes is much more 

noticeable than the corresponding probabilities for earthquakes. 

Currently, these statements of probability are the best we can do. 

Because they express mean values over long periods of time, they 

tell little about what will really happen this year or next year, but 

they may give a hint as to what will happen in our lifetime. Professional disaster planners must assume that disastrous hazards may 

occur at any time. 

3.2.4 Risk: How Dangerous are They?

Deaths and injuries from natural hazards are serious, but are not 

statistically large on an annual basis (e.g., compared to deaths 

from automobile accidents); nor have we recently encountered 

the number of deaths caused by the Johnstown, Pennsylvania, dam 
MULTIHAZARD DESIGN 3-9

failure and flood of 1889 (3,000 killed) or the Galveston, Texas, 

hurricane of 1900 (6,000 killed). 

Deaths from earthquakes in the United States have been quite 

small (e.g., less than 200 people have been killed since 1971, including the San Fernando, California, earthquake that killed 65 

people in that year and the later Loma Prieta and Northridge, 

California, earthquakes). However, the experience of Kobe, 

Japan, in 1995, when over 6,000 people were killed, shows that we 

cannot be complacent as to the ability of a modern city to withstand a direct hit. 

A major concern for those working on reducing earthquake risks 

is that the United States has yet to experience a large earthquake 

in an urban location (such as the 1906 San Francisco earthquake 

or the New Madrid, Missouri, earthquakes of 1811 and 1812) that 

seismologists believe to be inevitable. The Northridge earthquake 

of 1994 caused approximately 60 deaths, with economic losses 

estimated to be over $30 billion. In January 1995, on the anniversary of the Northridge earthquake, an earthquake in Kobe, Japan, 

caused more than 6,000 deaths and economic losses estimated to 

be over $85 billion. 

Since the Loma Prieta, Northridge, and Kobe earthquakes occurred, several analyses have been conducted on the potential 

effects of large earthquakes in California. It is estimated that a 

repeat of the 1906 earthquake on the San Andreas Fault near San 

Francisco would result in 3,000 to 8,000 deaths (depending on 

the time of day) with economic losses from $170 billion to $225 

billion in today’s dollars. It is also estimated that a magnitude 7 

earthquake (a moderate to large shock) on the Newport-Inglewood Fault in Southern California would kill between 3,000 and 

8,000 people and the economic losses would range from $175 billion to $220 billion.1

1 Bendimerad, F., Earthquake Scenarios in Three Cities: San Francisco, Los Angeles and Tokyo, 

 Proceedings, 11th World Conference on Earthquake Engineering, Acapulco, 

Mexico, 1996.
3-10 MULTIHAZARD DESIGN 

Earthquake-caused fires have historically been a major cause of 

casualties, most notably in the Tokyo earthquake of 1923. Approximately 30,000 people were killed in a single fire storm in a park 

along the Sunida River. Severe damage and casualties were caused 

by fires in the San Francisco earthquake of 1906 and the Kobe, 

Japan, earthquake of 1995.2

In the period between 1987 and 1997, floods caused 407 deaths: 

187 were caused by the 1996 blizzard and flood in the Northeast. 

Hurricanes caused 599 deaths, 270 of which occurred in the 1993 

blizzard and storm in the eastern United States. Although these 

numbers for hurricanes are substantial, relative to the size of the 

impacted area, the number of casualties is much less than in tornadoes. Between 1985 and 1997, the National Weather Service 

Storm Prediction Center reported 15 deaths in schools alone, of 

which 9 occurred in 1989.

Statistics for deaths from natural hazards over a recent 20-year period, on a mean annual basis, are as follows:3

❍ Earthquakes .......................................... 6

❍ Flash floods ....................................... 160

❍ Hurricanes .......................................... 30

❍ Tornadoes ......................................... 100

3.2.5 Cost: How Much Damage Will They 

Cause?

In the last two decades, losses from natural hazards have escalated. 

During the period from 1987 to 1997, floods caused $30 billion 

to $37 billion in damage, of which $15 billion was due to the Midwest floods of 1993. In the same 10-year period, hurricanes caused 

losses of between $60 billion to $66 billion, of which $27 billion 

was due to Hurricane Andrew in Florida and Louisiana. 

2 Arnold, C., Reconstruction After Earthquakes: Chapter Vb Toyko, Japan 1923 and 1945, Building 

 Systems Development, Inc., Palo Alto, CA, 1990.
MULTIHAZARD DESIGN 3-11

The three major California earthquakes that occurred in the period (Whittier Narrows, 1987, Loma Prieta, 1989, and Northridge 

1994) caused some $36.5 billion in damages.

A statistical comparison of percentage of occurrence of property 

and economic losses between January 1986 and December 1992 is 

as follows:4

❍ Earthquakes .......................................... 3

❍ Hurricanes/Tropical storms ...............48

❍ Tornadoes/Other winds .....................40

❍ Fire/Explosion .......................................5

❍ Miscellaneous.........................................4

Although these statistics relate to events prior to the Northridge 

earthquake of 1994 and also predate a number of significant 

floods and hurricanes, the relative importance of each hazard has 

not changed significantly, even though the overall dollar values 

involved have increased sharply.

One cause of this serious increase in the social and economic impacts of natural hazards is the rapid pace and intensity of urban 

and suburban development since World War II, particularly in 

states such as California, the Carolinas, and Florida, all of which 

have their own high hazard probability. Another is the high cost 

of construction, now soaring to levels inconceivable only a few 

decades ago. A third problem is that our political, economic, and 

social mechanisms for decision-making are still ill equipped to 

deal with the multi-faceted problems of reducing the risks and 

consequences of natural disasters. 

3.3 COMPARATIVE LOSSES

The HAZUS-MH (Hazards U.S.-Multihazards) program was developed by the Federal Emergency Management Agency (FEMA) 

4 Perry, D., Buildings at Risk, Multi-Hazard Design for Earthquakes, Winds and Floods, American 

 Institute of Architects, Washington, DC, not dated.
3-12 MULTIHAZARD DESIGN 

to produce loss estimates for use by federal, state, regional, and 

local governments to plan for damage, prepare emergency response and recovery programs, and to help examine options to 

reduce future damage. HAZUS-MH is a Geographic Information 

System (GIS)-based program designed to help communities estimate future losses. The methodology covers nearly all aspects 

of the built environment and a wide range of losses. Originally 

developed to assess risks from earthquakes, the methodology has 

been expanded to address floods throughout the U.S. and hurricanes in the Atlantic and Gulf coast regions.

In order to obtain an indication of the magnitude of losses and 

their relative significance for the three hazards considered in 

this manual, a “Level 1” HAZUS-MH analysis was conducted for 

educational facilities in six areas of the United 

States. A Level 1 analysis uses the building 

inventory in the HAZUS-MH program and is 

intended to give a broad picture of damage and 

loss on a regional basis.

The analysis was a regional loss analysis and was 

based on the building information for the EDU 

1 occupancy class in the general building stock 

module from the upcoming release of HAZUSMH. (This occupancy class is the HAZUS-MH 

designation for the school building inventory.) 

The regions chosen were those prone to two or 

more of the hazards addressed in HAZUS-MH, 

and deemed to provide a useful range geographic range. For each region and applicable 

hazard, probabilistic losses for a 100-and 500-

year return period event (earthquake, flood, or 

high wind) were computed. The column “EDU 

1 Exposure” in Table 3-1 refers to the total 

school inventory in each region.

Due to the developmental status of 

HAZUS-MH Build 27E at the time of 

publication of this manual, it was not 

possible to use the program for the 

flood values. Instead the following 

procedure was used: Q3 flood data 

were used for each of the counties 

listed below in defining the extent of 

the 100-year and 500-year flood areas 

(this is similar to a Level 2 approach in 

HAZUS-MH). The Q3 flood data are 

developed by electronically scanning 

the current effective map panels of 

existing paper Flood Insurance Rate 

Maps (FIRMs). Q3 flood data capture 

certain key features from the existing 

paper FIRMs. 30-meter resolution USGS 

digital elevation data and the Q3 

flood data were used to obtain flood 

elevation depths at different locations 

(using ArcGIS 3-D Analyst).
MULTIHAZARD DESIGN 3-13

The following regions were evaluated:

❍ Charleston County, South Carolina (Charleston) (earthquake, 

flood, and hurricane)

❍ Shelby County, Tennessee (Memphis) (earthquake and flood)

❍ Bexar County, Texas (San Antonio) (hurricane and flood)

❍ Salt Lake County, Utah (Salt Lake) (earthquake and flood)

❍ Suffolk County, Massachusetts (Boston) (earthquake, flood, 

and hurricane)

❍ Hillsborough County, Florida (Tampa) (hurricane and flood)

Table 3-1 is a summary of the results for the earthquake, wind, and 

flood scenarios as outlined above. 

Table 3-2 shows another comparison of these losses in the form of 

the percentage loss of school inventory for each event. It is instructive to note, in some cases, the wide disparity in losses between the 

100-year and 500-year events.

 Charleston, SC Earthquake Hurricane Flood EDU 1 Exposure

100-yr 500-yr 100-yr 500-yr 100-yr 500-yr

Building Damage 31 3,449 5,802 22,290 1,378 1,554 63,787 Building

Contents and Inventory 4 1,365 3,690 16,897 392 557 63,787 Contents

Business Interruption 5 320 2,052 6,558 NE NE

TOTAL 40 5,134 11,544 45,745 1,770 2,111

Table 3-1: HAZUS-MH Earthquake, Hurricane, and Flood Losses (All values are in $1,000s (2002 valuation))

Shelby, TN Earthquake Hurricane Flood EDU 1 Exposure

100-yr 500-yr 100-yr 500-yr 100-yr 500-yr

Building Damage 243 10,464 4,184 6,784 137,927 Building 

Contents and Inventory 53 3,723 1,203 2,002 137,927 Contents

Business Interruption 29 916 NE NE

TOTAL 325 15,103 5,387 8,786
3-14 MULTIHAZARD DESIGN 

Bexar, TX Earthquake Hurricane Flood EDU 1 Exposure

100-yr 500-yr 100-yr 500-yr 100-yr 500-yr

Building Damage 94 2,753 1,502 2,384 238,608 Building

Contents and Inventory 5 1,259 487 727 238,608 Contents

Business Interruption 7 2,078 NE NE

TOTAL 106 6,090 1,989 3,111

Salt Lake, UT Earthquake Hurricane Flood EDU 1 Exposure

100-yr 500-yr 100-yr 500-yr 100-yr 500-yr

Building Damage 2,175 30,313 15 204 177,728 Building

Contents and Inventory 881 9,016 4 57 177,728 Contents

Business Interruption 259 2,488 NE NE

TOTAL 3,315 41,817 19 261

Suffolk, MA Earthquake Hurricane Flood EDU 1 Exposure

100-yr 500-yr 100-yr 500-yr 100-yr 500-yr

Building Damage 0 1,544 4,837 58,640 254 907 268,311 Building

Contents and Inventory 0 484 2,258 40,665 70 305 268,311 Contents

Business Interruption 0 172 2,871 18,316 NE NE

TOTAL 0 2,200 9,966 117,621 324 1,212

Hillsborough, FL Earthquake Hurricane Flood EDU 1 Exposure

100-yr 500-yr 100-yr 500-yr 100-yr 500-yr

Building Damage 10,257 47,213 10,727 11,776 175,981 Building

Contents and Inventory 6,045 39,016 4,329 4,624 175,981 Contents

Business Interruption 4,291 13,004 NE NE

TOTAL 20,593 99,233 15,056 16,400

Notes:

EDU 1 Exposure: total school and contents inventory in each region (2003).

NE: HAZUS did not estimate these losses.

0: Evaluated, but no losses.

Boxes left blank have little or no activity for the referenced hazard.

Table 3-1: HAZUS-MH Earthquake, Hurricane, and Flood Losses (All values are in $1,000s (2002 valuation)) (continued)
MULTIHAZARD DESIGN 3-15

Table 3-2: HAZUS-MH Estimated Losses by Percentage of School Building and Contents Inventory

Earthquake Hurricane Flood

County 100-year 500-year 100-year 500-year 100-year 500-year

Charleston, SC 0.2 17.3 4.54 17.50 1.38 1.65

Shelby, TN 0.12 5.47 1.95 2.46

Bexar, TX 0.02 1.27 0.40 0.65

Salt Lake, UT 1.1 11.76 0.01 0.07

Suffolk, MA 0 0.8

Hillsborough, FL 5.85 28.20 4.27 4.65

Notes:

Boxes left blank have little or no activity for the referenced hazard.

This HAZUS-MH study, though limited in scope and relying on 

built inventory information, reveals some useful information:

❍ Generally, the 100-year earthquake causes insignificant 

damage, except in Salt Lake City, UT ($3 million).

❍ The 500-year earthquake causes the most damage in Salt 

Lake City, UT ($42 million), followed by Shelby, TX ($15 

million) and Charleston, SC ($5 million).

❍ The 100-year flood causes by far the most damage in Hillsborough, FL ($15 million; however, the 500-year flood causes 

only another $1 million in damage). In Shelby, TN, the 100-

year flood causes $5 million in damage and the 500-year flood 

causes $9 million. Elsewhere, flood damage is insignificant. 

❍ The 100-year hurricane causes the most damage in 

Hillsborough, FL ($20.5 million), followed by Charleston, SC 

($11.5 million) and Suffolk, MA ($10 million).

❍ The 500-year flood causes $118 million in damage in Suffolk, 

MA, $99 million in damage in Hillsborough, FL, and $46 

million in damage in Charleston, SC.
3-16 MULTIHAZARD DESIGN 

Charleston, SC, has the greatest combined threat from earthquakes and hurricanes; Hillsborough, FL, has the greatest 

combined threat from hurricanes and floods. 

The relatively modest damage figures shown in this study could 

be changed dramatically by a single large event, whether an earthquake, flood, or hurricane. It should also be noted that none of 

these locations were on the west coast and, thus, the damage figures for earthquakes are low. 

 3.4 FIRE AND LIFE SAFETY

Of the many hazards that can endanger a school facility and its 

service to the community, the most prevalent is fire. This is more 

pervasive than any of the hazards noted above. However, design 

against fire has long been built into our building codes, in the 

form of approved materials, fire-resistant assemblies, exiting 

requirements, the width and design of stairs, the dimensions 

of corridors, fire suppression systems, and many other issues. 

In fact, fire considerations are now so embedded in our design 

culture and regulation that there is a real danger that some designers may not fully realize that fire hazard is a specific design 

issue that must be considered.

According to the Special Report on Educational Property Structure 

Fires in the United States published by the NFPA in 1989, an average of 11,100 structural fires occur annually in educational 

properties. These fires resulted in a direct property loss of nearly 

$100 million, with 236 injuries and 3 fatalities. According to both 

NFPA and the United States Fire Administration (USFA), a substantial number of fires in schools are the result of arson.

Fires in older school buildings often result in a total loss of the 

building. This is due to a variety of factors, which include: delay 

of discovery and alarm, remote locations, lack of fire walls and/or 

compartmentation, lack of draft stopping in combustible attics, 

lack of automatic fire sprinkler systems, and inadequate water 

supplies for manual fire suppression activities. Losses in build-
MULTIHAZARD DESIGN 3-17

ings without automatic fire alarm and detection systems are twice 

those in buildings with such systems. Additionally, fire losses in 

buildings without automatic fire sprinkler protection are five 

times higher than those in buildings protected by sprinklers.

Often there appears to be a concern that there is not enough 

water for automatic fire sprinklers. The reality is that the water 

supply necessary for the proper operation of an automatic fire 

sprinkler system is far less than the amount of water necessary 

for manual fire suppression by the fire department. As an example, the water supply for a fire sprinkler system protecting a 

typical school building would be in the 350 gallons per minute 

(gpm) range, although 2,500 gpm or more would be required by 

a typical school building without sprinklers.

Since the 1970s, the provisions of the various building codes 

have continued to improve the level of fire and life safety of 

new school facilities. The level of fire and life safety in existing 

buildings is, however, another matter because the provisions 

of the various building codes are generally not applied to existing facilities except when renovations or additions are made 

and then only to the new work. Given that the average age of 

a school facility in the United States is currently 42 years, it is 

highly likely that older buildings do not provide the same level 

of protection as newer buildings. In order to protect these 

older facilities, their levels of fire and life safety must be evaluated. After an evaluation has been conducted, solutions using 

prescriptive and/or performance approaches can be developed 

and undertaken.

One system of evaluation is that contained in the existing 

structures chapter of the International Building Code. The “compliance alternatives” section provides a way of evaluating the 

overall level of fire and life safety in an existing building. Although the provisions of this section are generally intended to 

be applied to an existing building during changes in occupancy 

or renovation, it can provide the basis for the evaluation of any 

existing building. 
3-18 MULTIHAZARD DESIGN 

The evaluation comprises three categories: fire safety, means of 

egress, and general safety. The fire safety evaluation includes structural fire resistance, automatic fire detection, and fire alarm and 

fire suppression systems. Included within the means of egress portion are the configuration, characteristics, and support features 

for the means of egress. The general safety section evaluates various fire safety and means of egress parameters. The evaluation 

method generates a numerical score in the various areas, which 

can then be compared to mandatory safety scores. Deficiencies in 

one area may be offset by other safety features.

Another method of evaluating and upgrading an existing facility 

is the application of the provisions of the NFPA 101 Life Safety 

Code. Unlike the provisions of the various building codes, this 

document is intended to be applied retroactively to existing 

facilities and has a chapter specifically for existing educational 

occupancies. Even if this code is not adopted by the local jurisdiction, it can be used as the basis for an evaluation of any 

existing facility.

There is no question that upgrading an existing school facility can 

be costly. However, the cost of upgrades is far less than the direct 

and indirect losses of the facility to fire. The most effective method 

of providing fire protection is through automatic fire sprinklers, 

but other lower cost methods can be utilized, including:

❍ Automatic fire alarm and detection

❍ Draft stopping in combustible attic spaces

❍ Smoke and fire compartmentation walls in occupied spaces

Upgrades in fire and life safety can often be coordinated with 

other building renovations or upgrades to help reduce costs. For 

instance, draft stopping could be installed in a wood framed attic 

during roof deck replacement. Fire sprinklers could be installed 

during asbestos abatement or ceiling replacement/upgrades for 

seismic concerns. 
MULTIHAZARD DESIGN 3-19

3.5 HAZARD PROTECTION METHODS 

COMPARISONS: REINFORCEMENTS AND 

CONFLICTS

An important aspect of designing against all hazards in an integrated approach is that the methods used for design may 

reinforce one another or may conflict with one another; in the 

former case, the costs of multihazard design can be reduced, 

but, in the latter, they may be increased. Table 3-3 summarizes 

the effects that design for more than one hazard may have on 

the performance and cost of the building, addition, or repair. 

The horizontal rows show the five primary hazards. The vertical 

rows show methods of protection for the building systems and 

components that have significant interaction, either reinforcement or conflict. These methods are taken from the extended 

descriptions of risk reduction methods for the three main 

natural hazards discussed herein, together with the methods for 

security/blast protection presented in FEMA 428, Primer to Design Safe School Projects in Case of Terrorist Attacks. In addition, the 

interactions of these four categories of risk protection with fire 

safety, where they occur, are also shown. 

The designations are intended to provoke thought and design 

integration; they are not absolute restrictions or recommendations. In general, reinforcement between hazards may be gained 

and undesirable conditions and conflicts can be resolved by 

coordinated design between the consultants, starting at the inception of design. The reader is encouraged to use the list as a 

basis for discussion relative to specific projects and to structure 

the benefits and conflicts of multihazard design depending on 

local hazards.

Table 3-3 also provides information to help the reader to develop a list of reinforcements and conflicts for the particular 

combination of hazards that may be faced. Development of lists 

such as these can be used to structure initial discussions on the 

impact of multihazard design on the building performance and 
3-20 MULTIHAZARD DESIGN 

Building System Protection Methods: Reinforcements and Conflicts

System 

ID

Existing Conditions or 

Proposed Protection 

Methods

The Hazards

Earthquake Flood Wind Security/Blast

(FEMA 428) Fire Discussion Issues

1 Site

1-1 Building elevated 

on fill

     Excellent solution for flood. 

1-2 Two means of site 

access

    

1-3 In close proximity to 

other facilities that are high 

risk targets for attack 

    

Table 3-3: Multihazard Design System Interactions 

cost that, in turn, guide an integrated design strategy for multihazard protection. The system and component heading list is 

similar to that used for the building security assessment checklist in FEMA 426, Reference Manual to Mitigate Potential Terrorist 

Attacks Against Buildings. 

Key

 Indicates desirable condition or method for designatedcomponent/system 

 Indicates undesirable condition or method for designated component/system 

 Indicates little or no significance for designated component/system

Split box indicates significance may vary, see discussion issues
MULTIHAZARD DESIGN 3-21

Table 3-3: Multihazard Design System Interactions (continued)

Building System Protection Methods: Reinforcements and Conflicts

System 

ID

Existing Conditions or 

Proposed Protection 

Methods

The Hazards

Earthquake Flood Wind Security/Blast

(FEMA 428) Fire Discussion Issues

2 Architectural

2A Configuration

2A-1 Large roof overhangs      Possibly vulnerable to vertical forces 

in earthquake, uplift wind forces. The 

wall to roof intersection will tend to 

contain and concentrate blast forces 

if the point of detonation is below the 

eaves.

2A-2 Re-entrant corner 

(L-, U-shape, etc.) building 

forms

     May concentrate wind or blast forces; 

may cause stress concentrations and 

torsion in earthquakes.

2A-3 Enclosed courtyard 

building forms

      May cause stress concentrations and 

torsion in earthquake; courtyard 

provides protected area against 

high winds. Depending on individual 

design, they may offer protection or 

be undesirable during a blast event. 

If they are not enclosed on all four 

sides, the “U” shape or re-entrant 

corners create blast vulnerability. If 

enclosed on all sides, they might experience significant blast pressures, 

depending on building and roof design. Because most courtyards have 

significant glazed areas, this could be 

problematic.

2A-4 Very complex 

building forms

     May cause stress concentrations and 

torsion in highly stressed structures, 

and confusing evacuation paths and 

access for firefighting. Complicates 

flood resistance by means other than 

fill.

2B Planning and Function (No significant impact)
3-22 MULTIHAZARD DESIGN 

2C Ceilings (No significant impact)

2D Partitions

2D-1 Block, hollow clay 

tile partitions

     Wind and seismic force reactions 

would be similar for heavy 

unreinforced wall sections, with risk of 

overturning. Tile may become flying 

debris during a blast. It is possible, 

but difficult, to protect structures with 

blast walls, but a weak nonstructural 

wall has more chance of hurting 

people as debris. Desirable against 

fire and not seriously damaged by 

flood.

2D-2 Use of non-rigid 

connections for attaching 

interior non-load bearing 

walls to structure

     Non-rigid connections are necessary 

to avoid partitions influencing 

structural response. However, gaps 

provided for this threaten the fire 

resistance integrity and special 

detailing is necessary to close gaps, 

but retain ability for independent 

movement. 

2D-3 Gypsum wallboard 

partitions

     Although gypsum wallboard 

partitions can be constructed to 

have a fire resistance rating, they 

can be easily damaged during fire 

operations. Such partitions can be 

more easily damaged or penetrated 

during normal building use.

2D-4 Concrete block, 

hollow clay tile around exit 

ways and exit stairs

      May create torsional structural 

response and/or stress concentration 

in earthquakes in frame structures 

unless separated and, if unreinforced, 

wall is prone to damage. Properly 

reinforced walls preserve evacuation 

routes in case of fire or blast.

Table 3-3: Multihazard Design System Interactions (continued)

Building System Protection Methods: Reinforcements and Conflicts

System 

ID

Existing Conditions or 

Proposed Protection 

Methods

The Hazards

Earthquake Flood Wind Security/Blast

(FEMA 428) Fire Discussion Issues
MULTIHAZARD DESIGN 3-23

2E Other Elements

2E-1 Heavy roof

(e.g. slate, tile)

      Heavy roofs are undesirable in 

earthquakes; slates and tiles may 

detach. Heavy roofs provide good 

protection from fire spread, but can 

also cause collapse of a fire-weakened 

structure. Almost always used on steepsloped roofs; if wind-blown debris or 

a blast wave hits them, they become 

flying debris and dangerous to people 

outside the building.

2E-2 Parapet       Properly engineered parapet is OK 

for seismic; unbraced unreinforced 

masonry (URM) is dangerous. May 

assist in reducing the fire spread.

3 Structural Systems

3-1 Heavy structure: 

reinforced concrete (RC) 

masonry, RC or masonry 

fireproofing of steel

     Increases seismic forces, but generally 

beneficial against other hazards.

3-2 Light structure: steel/

wood 

     Decreases seismic forces, but generally 

less effective against other hazards. 

3-3 URM exterior load 

bearing walls

    

3-4 Concrete or reinforced 

CMU exterior structural walls 

    

3-5 Soft/weak first story       Very poor earthquake performance, 

and vulnerable to blast. Generally 

undesirable for flood and wind. 

Elevated first floor is beneficial for 

flood if well constructed, but should 

not be achieved by a weak structure 

that is vulnerable to wind or flood 

loads.

Table 3-3: Multihazard Design System Interactions (continued)

Building System Protection Methods: Reinforcements and Conflicts

System 

ID

Existing Conditions or 

Proposed Protection 

Methods

The Hazards

Earthquake Flood Wind Security/Blast

(FEMA 428) Fire Discussion Issues
3-24 MULTIHAZARD DESIGN 

3-6 Indirect load path      Undesirable for highly stressed 

structures, and fire weakened structure 

is more prone to collapse. Not critical 

for floods.

3-7 Discontinuities in 

vertical structure

     Undesirable for highly stressed 

structures causes stress concentrations, 

and fire-weakened structure is more 

prone to collapse. Not critical for 

floods.

3-8 Seismic separation 

joints

     Possible path for toxic gases to 

migrate to other floors. 

3-9 Ductile detailing and 

connections/steel

     Provides a tougher structure that is 

more resistant to collapse.

3-10 Ductile detailing/RC      Provides a tougher structure that is 

more resistant to collapse.

3-11 Design for uplift 

(wind)

     Necessary for wind; may assist in 

resisting seismic or blast forces.

3-12 Concrete block, 

hollow clay tile around exit 

ways and exit stairs

     May create torsional structural 

response and/or stress concentration 

in earthquakes in frame structures 

unless separated, and if unreinforced 

wall is prone to damage. Properly 

reinforced walls preserve evacuation 

routes in the event of fire or blast.

4 Building Envelope

4A Wall Cladding

4A-1 Masonry veneer on 

exterior walls

     In earthquakes, material may detach 

and cause injury. In winds and attacks, 

may detach and become flying debris 

hazard. Flood forces can separate 

veneer from walls.

Table 3-3: Multihazard Design System Interactions (continued)

Building System Protection Methods: Reinforcements and Conflicts

System 

ID

Existing Conditions or 

Proposed Protection 

Methods

The Hazards

Earthquake Flood Wind Security/Blast

(FEMA 428) Fire Discussion Issues
MULTIHAZARD DESIGN 3-25

Notes: 

The table refers to typical school structures: steel frame, concrete block or RC walls, wood frame, 1-2 stories suburban, 2-4 stories urban.

Table 3-3: Multihazard Design System Interactions (continued)

Building System Protection Methods: Reinforcements and Conflicts

System 

ID

Existing Conditions or 

Proposed Protection 

Methods

The Hazards

Earthquake Flood Wind Security/Blast

(FEMA 428) Fire Discussion Issues

4B Glazing

4B-1 Metal/glass curtain 

wall

     Fire can spread upward behind the 

curtain wall if not properly firestopped. Not blast-resistant without 

special glass and detailing. Light 

weight reduces earthquake forces. 

4B-2 Impact-resistant 

glazing

     Can cause problems during fire 

suppression operations, limiting access 

and smoke ventilation.

5 Utilities (No significant impact)

6 Mechanical

6-1 Heating, ventilation, 

and air conditioning (HVAC) 

system designed for purging 

in the event of fire

     Can be effective in reducing chemical, 

biological, or radiological (CBR) threat 

if it has rapid shut-down and efficient 

dampers, and is located in an airtight 

building.

6-2 Large rooftopmounted equipment 

     Vulnerable to earthquake and wind 

forces. Raises equipment above floor 

level.

7 Plumbing and Gas (No significant impact)

8 Electrical (No significant impact)

9 Fire Alarm (No significant impact)

10 Communications and IT (No significant impact)

11 Equipment O&M (No significant impact)

12 Security (No significant impact)

12A Perimeter Systems (No significant impact)

12B Interior Security (No significant impact)

12C Security System Documents (No significant impact)

13 Security Master Plan (No significant impact)
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4

MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-1

4.1 INTRODUCTION

T his chapter outlines the earthquake risk to schools and the 

processes and methods that can be used to reduce it. An 

explanation of the nature and probability of earthquakes is 

provided, together with procedures for determining the earthquake 

threat to specific locations. An assessment of the scope and effectiveness of seismic building codes is followed by an explanation of how 

to evaluate the vulnerability of a school building. Current methods 

of designing for seismic resistance in new buildings and upgrading 

existing buildings lead to a discussion on determining acceptable 

risk and the use of performance-based design to achieve community 

objectives in providing for seismic safety. 

4.2 THE NATURE AND PROBABILITY OF 

EARTHQUAKES 

Although earthquakes cannot be prevented, modern science and 

engineering provide tools that can be used to reduce their effects. 

Science can now identify, with considerable accuracy, where earthquakes are likely to occur and what forces they will generate. This 

information is readily available and can be obtained for local geographic regions (see Section 4.2.3). 

4.2.1 Earthquakes and Other Geologic 

Hazards

Earthquakes have long been feared as one of nature’s most terrifying phenomena. Early in human history, the sudden shaking 

of the earth and the death and destruction that resulted were 

seen as mysterious and uncontrollable. We now understand the 

origin of earthquakes and know that they must be accepted as a 

natural environmental process. Scientific explanations, however, 

have not lessened the terrifying nature of the earthquake experience. Earthquakes continue to remind us that nature can, without 
4-2 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

warning, in a few seconds create a level of death and destruction 

that can only be equaled by the most extreme weapons of war.

This uncertainty, together with the terrifying sensation of earth movement, creates our fundamental fear of earthquakes. Beyond the 

threat to life is the possibility of the destruction of public and private 

property. Jobs, services, and business revenues can disappear instantly 

and, for many, homelessness can suddenly be very real. The aftermath of a great earthquake can endure for years or even decades. 

Other types of phenomena sometimes accompany earthquake-caused 

ground shaking and are generally identified as geologic hazards:

❍ Liquefaction occurs when loose granular soils and sand in 

the presence of water change temporarily from a solid to a 

liquid state when subjected to ground shaking. This condition 

occurs mainly at sites located near rivers, lakes, and bays. 

❍ Landslides, which involve the slipping of soil and rock on 

sloping ground, can be triggered by earthquake ground 

motion (see Figure 4-1).

❍ Tsunamis are earthquake-caused wave movements in the 

ocean that travel at high speed and may result in large coastal 

waves of 30 feet or more. They are sometimes, and incorrectly, 

called tidal waves.

❍ Seiches are similar to tsunamis, but take the form of sloshing 

in closed lakes or bays; they have the potential to cause serious 

damage, although such occurrences have been very rare. 

For all of the above geologic hazards, the only truly effective 

defense is the application of good land-use practices that limit 

development in hazard-prone locations. Seismic design and 

construction is aimed at reducing the consequences of earthquake-caused ground shaking, which is by far the main cause of 

damage and casualties. 
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-3

4.2.2 Earthquakes: A National 

Problem

Earthquakes in the United States are a national 

problem. This was recognized by the U.S. Congress 

in 1977 when it passed legislation authorizing the 

National Earthquake Hazards Reduction Program (NEHRP), 

which has supported considerable research and hazard mitigation 

implementation since that time. 

Most people now know that earthquakes are not restricted to just a 

few areas in the United States, most notably California and Alaska, 

and that two of the greatest earthquakes known occurred not in 

California, but near New Madrid, Missouri, in 1811 and 1812. As 

shown on a map of earthquake probability in the U.S., more than 

40 of the 50 states are at risk from earthquake-caused damage, life 

loss, injuries, and economic impacts (see Figure 4-2). Certainly the 

likelihood of a damaging earthquake occurring west of the Rocky 

Mountains, and particularly in California, the states of Oregon 

and Washington, and Salt Lake City, is much greater than it is in 

the East, Midwest, or South. However, the New Madrid, Missouri, 

and Charleston, South Carolina, regions are subject to the possibility of severe earthquakes, although with a lesser probability than 

the western U.S.

Figure 4-1 

School, Anchorage, AK, 

1964, severely damaged 

by earthquake-induced 

landslide

SOURCE: NATIONAL INFORMATION 

SERVICE FOR EARTHQUAKE 

ENGINEERING, UNIVERSITY OF 

CALIFORNIA, BERKELEY
4-4 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

There are several common measures of earthquakes. Perhaps 

the most familiar is the Richter Magnitude, devised by Professor 

Charles Richter of the California Institute of Technology in 1935. 

Richter’s scale is based on the maximum amplitude of certain 

seismic waves recorded on a standard seismograph at a distance 

of 100 kilometers (km) from the earthquake epicenter. Because 

the instruments are unlikely to be exactly 100 km from the 

source, Richter devised a method to allow for the diminishing 

of wave amplitude with increased distance. The Richter scale 

is logarithmic, and each unit of magnitude indicates a ten-fold 

increase in wave amplitude. The energy increase represented 

by each unit of scale is approximately 31 times. The scale is 

open-ended, but a magnitude of about 9.5 represents the largest 

possible earthquake. 

Table 4-1 shows significant earthquakes (Magnitude 6 or over) 

that occurred in 47 of the 50 U.S. states between 1568 and 1989.

Figure 4-2 Map of the continental United States that shows counties and probabilities of 

earthquakes of varying magnitude

 SOURCE: USGS
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-5

Table 4-1: Known Historic (1568-1989) Earthquakes in 47 U.S. States

Number of Quakes with Reported Maximum 

Modified Mercali Intensity (MMI) of:

State VI VII VII+

Alabama 5 7 —

Alaska 41 21 13

Arizona 11 3 1

Arkansas 8 3 2

California 329 131 66

Colorado 19 1 —

Connecticut 2 1 —

Delaware — 1 —

Florida 2 — —

Georgia 5 — —

Hawaii 30 13 10

Idaho 12 4 2

Illinois 18 12 —

Indiana 5 2 —

Kansas 4 2 —

Kentucky 8 1 —

Louisiana 1 — —

Maine 7 2 —

Massachusetts 8 7 3

Michigan 1 1 1

Minnesota 3 — —

Mississippi 2 — —

Missouri 14 2 3

Montana 35 4 5

Nebraska 4 2 —

Nevada 28 10 8

New Hamshire 7 2 —

New Jersey 5 1 —

New Mexico 29 10 8

New York 16 6 2

North Carolina 5 2 —

North Dakota 1 — —

Ohio 9 5 1
4-6 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

Number of Quakes with Reported Maximum 

Modified Mercali Intensity (MMI) of:

State VI VII VII+

Oklahima 9 2 —

Oregon 10 1 —

Pennsylvania 7 1 —

Rhode Island 1 — —

South Carolina 17 2 1

South Dakaota 6 — —

Tennessee 12 2 —

Texas 7 1 —

Utah 31 8 5

Vermont 1 — —

Virginia 12 1 1

Washington 37 6 3

West Virgina 1 — —

Wyoming 8 1 —

SOURCE: U.S. GEOLOGICAL SURVEY, PROFESSIONAL PAPER 1527, 1993

NOTE: This list includes only earthquakes that affected human settlements.

Table 4-1: Known Historic (1568-1989) Earthquakes in 47 U.S. States (continued)

Records show that some seismic zones in the United States experience moderate to major earthquakes approximately every 50 to 70 

years, while other areas have “recurrence intervals” for the same 

size earthquake of about 200 to 400 years. These frequencies of 

occurrence are simply statistical probabilities and one or several 

earthquakes could occur in a much shorter than average period. 

With current knowledge, there is no practical alternative for those 

responsible for schools located in earthquake-prone regions but 

for them to assume that a large earthquake is likely to occur at any 

time and that appropriate action should be taken. 

Moderate and even very large earthquakes are inevitable, 

although very infrequent, in areas of normally low seismicity. Consequently, in these regions, buildings are very seldom designed 
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-7

to deal with an earthquake threat; therefore, they are extremely 

vulnerable. In other places, however, the earthquake threat is 

quite familiar. Schools in many areas of California and Alaska will 

be shaken by an earthquake perhaps two or three times a year and 

some level of “earthquake-resistant” design has been accepted as a 

way of life since the early 20th century. 

Although, on a national basis, the areas where earthquakes are 

likely to occur and the potential size or “magnitude” of these 

earthquakes are well identified and scientists have a broad statistical knowledge of the likelihood of their occurrence, it is not 

yet possible to predict the near-term occurrence of a damaging 

earthquake. Therefore, lacking useful predictions, it makes sense 

in any seismic region to take at least the minimum affordable prudent actions directed at saving lives. Because most lives are lost in 

earthquakes when buildings collapse, U.S. seismic building code 

provisions focus on requiring that the minimum measures necessary to prevent building collapse are taken.

In California, schools are further protected by the Field Act of 

1933, which mandated additional requirements relating to design 

qualifications, plan checking, and site inspection. (The Field Act is 

discussed in more detail in Section 4.3.2.)

The following graphics explain some earthquake terminology and 

characteristics of ground motion.
4-8 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

WHAT EARTHQUAKES DO

The Origin of Earthquakes

This diagram explains some of the common 

terms used in talking about earthquakes. 

Waves of vibration radiate out from the 

fault break.

Types of Seismic Waves

Four main types of waves radiate from a 

fault break. The P or Primary wave, a backand-forth motion, arrives first, followed by 

the S wave (secondary or shear) that is 

more of a rolling motion. These are deep 

waves that travel through the earth to the 

surface. The Love and Rayleigh waves, 

named after their discoverers, travel along 

the earth’s surface.

Motion at Site

Scratch left on a floor by a kitchen range 

in the 1933 Long Beach earthquake that 

shows the random nature of earthquake 

motion.
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-9

ACCELERATION FORCES

Forces and Gravity

Because ground motion waves produce 

inertial forces within structures, these 

forces obey Newton’s Second Law of 

Motion. This fundamental equation 

establishes the forces for which buildings 

must be designed to resist earthquakes.

Acceleration

The acceleration, or the rate of change 

of the velocity of the waves that set 

the building in motion, is used in an 

equation, derived from Newton’s Second 

Law of Motion to estimate the percentage 

of the building mass or weight that must 

be dealt with as a horizontal force.

Acceleration

Some common examples of acceleration. 

The skydivers are falling under the action 

of gravity, 1g.
4-10 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

SOURCE: BSSC: PRESENTATIONS TO THE ARCHITECTURAL COMMUNITY, 2001, CHRIS ARNOLD AND TONY ALEXANDER

PERIOD AND RESONANCE

Fundamental Period and Resonance

Every object has a fundamental period 

at which it vibrates if it is set in motion. It 

cannot vibrate at another period unless 

it is dragged back and forth. The ground 

also has a fundamental period. If an 

object is set in motion by an external force 

such as ground shaking, which is at the 

fundamental period of the object, the result 

will be “resonance” and the motion of the 

object will tend to increase. When you 

push a child on a swing, you instinctively 

give it a push at its fundamental period, 

which results in an enjoyable increase in 

the motion with very little force applied.

Similarly, if the ground pushes a building 

with the same period as the motion, the 

accelerations in the building will increase, 

perhaps four or five times.

Fundamental Period in Seconds

This shows typical periods for structures. 

The main determinant of period is building 

height and proportion; thus, a tall slender 

object will have a long period and sway 

back and forth quite slowly. So the 40-story 

building will sway gently back and forth 

once every 7 seconds.
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-11

4.2.3 Determination of Local Earthquake 

Hazards

Until quite recently, the United States was divided into a number 

of seismic zones, which were shown on the maps in the model 

codes. Zones ranged from Zone 0 (indicating no seismicity) to 

Zones 1, 2A, 2B, 3, and 4. Zone 4 indicates the highest level of 

seismicity (see Figure 4-3; only Zones 0, 1, 2A, and 3 are shown). 

Each zone was allocated a factor, or coefficient, from 0.075 to 

0.40; this value was a multiplier representing the acceleration 

value for which the building was to be designed. These values 

indicate a four-fold range in acceleration values between Zones 1 

and 4. Within a zone, all buildings must be designed to the same 

acceleration value (or greater); contour lines show the boundaries between zones.

Current codes, such as the International Building Code, define 

site seismicity in a different way. The United States is still divided 

into zones by contour lines, but their areas are much smaller. 

Numerical values are also shown on the maps and also represent 

the acceleration value to be used for design, but they are calculated in a different way, and many more values are shown that 

reflect greater precision of knowledge. Also, acceleration values 

for both long and short period buildings are shown in a separate 

series of maps. Figure 4-4 shows a portion of the earthquake 

ground motion map in the International Building Code 2003 

corresponding to the region shown in Figure 4-3. The simplicity 

of the old seismic zones is lost, but the design information is 

much more detailed.

If the school district or community desires to obtain more detailed information on the seismic hazard than is shown on the 

code maps, or if the location does not enforce a seismic code, 

but there is concern about seismicity, the U.S. Geological Survey 

(USGS) web page at www.USGS.gov, Earthquake Hazards Program, is an excellent resource. The USGS provides more detailed 

earthquake hazard maps for general regions such as the Western, 

Central, and Eastern U.S. 
4-12 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

Figure 4-3 

Map showing older 

seismic zones in part of 

the United States, from the 

1997 Uniform Building 

Code. The area in the 

box corresponds to the 

area in Figure 4-4.

SOURCE: INTERNATIONAL 

CONFERENCE OF BUILDING 

OFFICIALS, WHITTIER, CA

Figure 4-5 shows a comparison between the 

Southeast U.S. and 

California. The larger 

acceleration values for the 

latter are symbolized by the 

darker colors. These maps 

are used as the basis for the 

maps shown in the IBC. Figure 

4-6 shows a comparison, for the 

Southeast U.S., between acceleration values for a 1.0-second period 

building and a 0.2- second building. 

Note the larger acceleration values 

for the shorter period building. 

Figures 4-5 and 4-6 show values for 

a hypothetical earthquake with a 2-

percent probability of exceedance 

in 50 years. This can be visualized 

as the odds of occurrence. The 

seismic code section of the IBC 

also shows values for earthquakes 

with a 10-percent probability of 

occurrence in 50 years (i.e., much 

shorter odds).

For even more localized information, the USGS 

provides seismicity information for any location 

in the United States on the basis of latitude and longitude, or Zip 

Code. This information can be obtained by opening the Seismic 

Hazard listings on the USGS web page, and opening Hazards by 

Latitude and Longitude, or Hazards by Zip Code. These listings 

show information on the expected maximum shaking that is estimated for the location. The information and terminology are 

quite technical and may need to be interpreted by qualified staff 

at the responsible local code office, a structural engineer, or perhaps a knowledgeable seismic professional. 
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-13

Figure 4-4 

Portion of an earthquake 

ground motion map used 

in the International Building 

Code 2003 that shows 

contours that identify 

regions of similar spectral 

response accelerations 

to be used for seismic 

design. Spectral response 

acceleration includes both 

ground acceleration and 

effect of building period. 

This area corresponds 

to the area in the box in 

Figure 4-3. Many more 

acceleration values are 

shown in the newer map.

SOURCE: USGS/BSSC PROJECT 

97 BY BUILDING SEISMIC SAFETY 

COUNCIL, FEDERAL EMERGENCY 

MANAGEMENT AGENCY
4-14 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

Figure 4-5 

These maps compare the seismicity of the Southeast U.S. and California. The larger acceleration values 

for the latter are symbolized by the darker colors.

SOURCE: USGS

Figure 4-6 

These maps show a comparison for the Southeast U.S. between the acceleration values for a 1-second 

(long) and a 0.2-second (short) building period.

SOURCE: USGS
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-15

4.3 VULNERABILITY: WHAT EARTHQUAKES 

CAN DO TO SCHOOLS

This section reviews the experience of schools in earthquakes. 

Much of the information presented comes from California, because of the prevalence of earthquakes in that state. In general, 

the seismic performance of newer buildings has been good, although considerable costly and dangerous nonstructural damage 

still occurs. California public school design and construction has 

been subject to strict regulation since 1933 which undoubtedly 

contributes to good performance. Many of the damage examples shown in this section are of older buildings: this is relevant 

because schools are long-lived buildings and many schools constructed in the early decades of the 20th century are still in use.

4.3.1 Vulnerability of Schools 

Older unreinforced masonry school buildings present a very high 

risk, and this type of structure has been prohibited by law in California since the mid-1930s, following severe damage to schools 

of this type in the 1933 

Long Beach earthquake. 

A structural type that 

poses perhaps an even 

greater risk than unreinforced masonry 

is that of the mid-rise 

nonductile reinforced 

concrete frame. “Nonductile” refers to the 

frame’s lack of ductility 

(flexibility), or ability 

to deform considerably 

before breaking (see 

Figure 4-7). 

Figure 4-7 Ductility 

SOURCE: BSSC: PRESENTATIONS TO THE ARCHITECTURAL COMMUNITY, 2001, CHRIS ARNOLD 

AND TONY ALEXANDER
4-16 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

Reinforced concrete frames are made ductile by introducing an 

appropriate, code-specified amount of specifically designed steel 

reinforcing; unfortunately, the need for this was not recognized 

in seismic codes until the mid-1970s and so a large inventory of 

these types of structure exists (see Figure 4-8).

Figure 4-8 

Collapse of portion of 

nonductile concrete frame 

school structure, Helena, 

MT, 1935

SOURCE: NATIONAL INFORMATION 

SERVICE FOR EARTHQUAKE 

ENGINEERING, UNIVERSITY OF 

CALIFORNIA, BERKELEY

Wood frame structures perform effectively, provided that they 

are well constructed, particularly with respect to correct nailing 

of shear walls as specified in the code and properly detailed roofto-wall connections. Good maintenance, ensuring continued 

protection against moisture and wood attacking insects, is also 

critical for wood frames.

Newer structures, employing frames and fewer walls, also perform effectively if well designed and constructed; however, their 

response differs from that of shear wall structures, which are stiff 

and resistant to lateral forces. Frame structures are more flexible, 

which reduces the forces on the structural members and enables a 

light and safe structure to be designed. 

Modular classrooms are liable to topple off their foundations 

unless securely attached and braced. This damage is not lifethreatening, but makes the building unusable; fractured power, 

gas, and waste lines may be a hazard (see Figure 4-9).
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-17

Figure 4-9 

Modular classrooms 

pushed off their 

foundations; note stairs 

at left, Northridge, CA, 

1994.

SOURCE: GARY MCGAVIN,

REDLANDS, CA

If long-span roof and floor members are employed, however, there may be excessive drift, 

or sway, which causes damage to nonstructural components such as hung ceilings, 

light fixtures, light partitions, and contents. 

Piping, ductwork, electrical conduits, and 

communication pathways (cable trays) 

may also be damaged. Storage units, filing 

cabinets, and library shelving in any type of 

structure may be hazardous if not properly 

braced (see Figure 4-10). Broken pipes can 

create an additional hazard in the form of 

flooding, lack of fire protection water, and, 

with heating piping or domestic hot water 

piping, this could result in a flood of hot 

water.

School occupants are particularly vulnerable 

to nonstructural damage. Although students 

and staff may duck under desks and be safe 

from falling objects such as lighting fixtures 

and ceiling tiles, ceiling components that fall 

in hallways and stairs can make movement 

difficult, particularly if combined with power 

failure and loss of lights. Additional falling 

Figure 4-10 

Fallen filing cabinets and shelves, Northridge, 

CA, 1994

SOURCE: GARY MCGAVIN, REDLANDS, CA
4-18 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

hazards that are common in schools are large wall-mounted 

televisions (TVs) or ceiling mounted liquid crystal display (LCD) 

projectors. Heavy equipment can be hazardous and falling debris 

can also cause panic (see Figure 4-11).

Figure 4-11 

Fallen shop equipment, 

Coalinga, CA, 1983

SOURCE: GARY MCGAVIN, 

REDLANDS, CA

Pendant light fixtures have sometimes fallen if they are insecurely attached and not designed to swing freely (see Figure 

4-12). Sudden breakage of large glass areas is a specific hazard 

because of the dense occupancy in many school rooms; design 

of glazing to resist wind-borne debris and physical attack may 

also assist in protecting it from earthquake motion. This kind of 

damage has been significant in California schools that have suffered recent earthquakes.

Heavy hung lath and plaster ceilings in older auditoriums (and 

assembly buildings) can be dangerous and need careful inspection of their attachment and materials. If deficient in safety, 

replacement is the only acceptable solution (see Figure 4-13).
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-19

Figure 4-12 

Fallen light fixtures, library, Coalinga, CA, 1983

SOURCE: GARY MCGAVIN, REDLANDS, CA

Figure 4-13 

Fallen heavy lath and 

plaster ceiling across 

auditorium seating, 

Northridge, CA, 1994

SOURCE: GARY MCGAVIN, 

REDLANDS, CA
4-20 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

Figure 4-14 

Damage to the John Muir 

School, Long Beach, CA, 

1933

SOURCE: NATIONAL INFORMATION 

SERVICE FOR EARTHQUAKE 

ENGINEERING, UNIVERSITY OF 

CALIFORNIA, BERKELEY

 4.3.2 Earthquake Damage to Schools 

Most information on earthquake damage to schools comes from 

California. Its high incidence of earthquake activity has also resulted in sophisticated seismic building codes for all buildings and 

special plan checking and inspection requirements, enforced by 

the state, for school buildings. 

Considering the number of significant earthquakes in California 

since the early years of the 20th century, there has been remarkably little severe structural damage to schools, except in the Long 

Beach earthquake of 1933, and there have been very few casualties. In California, no school child has been killed or seriously 

injured since 1933. This good fortune has been primarily because 

all major California earthquakes since 1925 have occurred outside 

school hours (see Figure 4-14).

In the Long Beach earthquake that occurred at 5:55 p.m. on 

March 10, 1933, damage to unreinforced masonry school buildings was so severe that there would have been many casualties 

had they been occupied. As a result, the state passed the Field Act 

within a month of the earthquake (see Figures 4-15 and 4-16).
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-21

Figure 4-15 

Damage to shop building, 

Compton Junior High 

School, Long Beach, CA, 

1933

SOURCE: NATIONAL INFORMATION 

SERVICE FOR EARTHQUAKE 

ENGINEERING, UNIVERSITY OF 

CALIFORNIA, BERKELEY 

Figure 4-16 

A dangerous passage way between two 

buildings, Polytechnic High School, Long 

Beach, CA, 1933

SOURCE: NATIONAL INFORMATION SERVICE FOR 

EARTHQUAKE ENGINEERING, UNIVERSITY OF 

CALIFORNIA, BERKELEY
4-22 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

The Field Act required that all public school buildings be designed by a California licensed architect or structural engineer; 

all plans were to be checked by the then Department of General 

Services and construction was to be continuously inspected by 

qualified independent inspectors retained by the local school 

board. The Department of General Services set up a special division, staffed by structural engineers, to administer the provisions 

of the Act. The Field Act, which is still enforced today, has greatly 

reduced structural damage to California schools.

The earthquake also resulted in the passage of the Riley Act, 

which governed all buildings, with a few exceptions. The Riley 

Act required all buildings in the state to be designed to a specified lateral force, and effectively outlawed unreinforced masonry 

construction.

In 1952, a series of earthquakes occurred in Kern County, in the 

Bakersfield region, some 70 miles north of Los Angeles. Two 

groups of earthquakes occurred; the first, in the last week of July, 

included one with a magnitude of 7.6 on the Richter scale. The 

second group occurred in late August, and one earthquake, near 

the city of Bakersfield, had a magnitude of 5.9 on the Richter 

scale. There were 10 deaths in the July earthquake and 2 in the 

August earthquake.

This earthquake was of particular interest because the incidence 

of school damage might represent that of comparable earthquakes striking in regions today where seismic codes have not 

been adopted and enforced due to the rarity of seismic events (see 

Figures 4-17, 4-18, and 4-19).

There were no casualties in schools in 1952, because these earthquakes also occurred outside school hours. At that time, the Field 

Act had been in force for nearly 20 years, and the newer schools 

had been constructed to conform to its requirements. Of the 58 

masonry schools in the region, 18 had been constructed after the 

Field Act. Of these, one suffered moderate damage; this school 

was constructed of grouted reinforced brick masonry and in-
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-23

Figure 4-17 

A heavy corridor lintel 

ready to fall, Emerson 

School, Bakersfield, Kern 

County, CA, 1952

SOURCE: NATIONAL INFORMATION 

SERVICE FOR EARTHQUAKE 

ENGINEERING, UNIVERSITY OF 

CALIFORNIA, BERKELEY

Figure 4-18 

Overturned shop equipment and failed 

light fixtures, Kern County, CA, 1952

SOURCE: NATIONAL INFORMATION SERVICE FOR 

EARTHQUAKE ENGINEERING, UNIVERSITY OF 

CALIFORNIA, BERKELEY
4-24 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

Figure 4-19 

Destroyed exit corridor, 

Bakersfield, Kern County, 

CA, 1952

SOURCE: NATIONAL INFORMATION 

SERVICE FOR EARTHQUAKE 

ENGINEERING, UNIVERSITY OF 

CALIFORNIA, BERKELEY

curred approximately 1 percent damage. Of the 40 non-Field Act 

schools, 1 collapsed, 15 suffered severe damage, and 14 suffered 

moderate damage. In the Bakersfield City School District, 175 

classrooms and 6,500 students were displaced and only about 10 

classrooms could quickly be put back in service. There was considerable nonstructural damage to ceilings and light fixtures. 

In other states, similar damage to unreinforced masonry (URM) 

and early reinforced concrete structures occurred. Considerable 

damage to schools occurred in Helena, Montana, in 1935 (see 

Figure 4-20). In 1949, severe damage was inflicted on several 

URM schools, resulting in one fatality, in Seattle (see Figures 4-21 

and 4-22). At Puyallup High School, three boys on the stage just 

managed to escape when the roof collapsed (see Figure 4-23). 

Widespread damage to furniture and contents also occurred (see 

Figure 4-24). 
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-25

Figure 4-20 

Typical school damage, 

Helena, MT, 1935

SOURCE: NATIONAL INFORMATION 

SERVICE FOR EARTHQUAKE 

ENGINEERING, UNIVERSITY OF 

CALIFORNIA, BERKELEY

Figure 4-21 

The student body president was killed here by 

falling brickwork, Seattle, WA, 1949.

SOURCE: EARTHQUAKE ENGINEERING RESEARCH INSTITUTE, 

OAKLAND, CA. PHOTO FROM A.E. MILLER COLLECTION, 

UNIVERSITY OF WASHINGTON ARCHIVES
4-26 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

Figure 4-22 

Another dangerous entry 

collapse, Seattle, WA, 

1949

SOURCE: EARTHQUAKE 

ENGINEERING RESEARCH 

INSTITUTE, OAKLAND, CA. PHOTO 

FROM SEATTLE SCHOOL ARCHIVES

Figure 4-23 

Collapse of roof over stage, Seattle, WA, 

1949

SOURCE: NATIONAL INFORMATION SERVICE FOR 

EARTHQUAKE ENGINEERING, UNIVERSITY OF CALIFORNIA, 

BERKELEY
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-27

Figure 4-24 

Damage to library shelving, 

Seattle, WA, 1949

SOURCE: NATIONAL INFORMATION 

SERVICE FOR EARTHQUAKE 

ENGINEERING, UNIVERSITY OF 

CALIFORNIA, BERKELEY

4.3.3 Significant School Damage in Recent U.S. 

Earthquakes

In the Anchorage, Alaska, earthquake of 1964, which registered 

8.4 on the Richter scale, a number of public schools were damaged, but there were no collapses. The earthquake occurred on 

Good Friday at 5:36 p.m., when the schools were unoccupied. 

The most seriously damaged school was that shown previously in 

Figure 4-1; the school was subsequently demolished. At the West 

Anchorage High School (see Figures 4-25 and 4-26), a two-story 

nonductile concrete frame and shear wall classroom wing suffered 

severe structural damage and near total failure in a number of columns. Structural distortion also created a number of severe glass 

breakages. The second floor was removed during reconstruction 

and the first floor was repaired and retained.

In the San Fernando, CA, earthquake of 1971, there were no injuries and no schools collapsed; however, the earthquake caused 

$13.2 million in damages (in 1971 dollars), and 100 pre-Field Act 

schools were demolished within 11⁄2 years after the earthquake. 
4-28 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

Figure 4-25 

Severe structural damage to 

the West Anchorage High 

School, Anchorage, AK, 

1964

SOURCE: NATIONAL INFORMATION 

SERVICE FOR EARTHQUAKE 

ENGINEERING, UNIVERSITY OF 

CALIFORNIA, BERKELEY

Figure 4-26 

Brittle failure at nonductile concrete column, 

West Anchorage High School, 1964

SOURCE: NATIONAL INFORMATION SERVICE FOR 

EARTHQUAKE ENGINEERING, UNIVERSITY OF CALIFORNIA, 

BERKELEY
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-29

A survey of 1,544 public school buildings showed that only 

three schools sustained severe damage as a result of the Loma 

Prieta (San Francisco Bay area) earthquake of 1989. A portable 

classroom near Santa Cruz was rocked off its unbraced and 

unanchored supports. An elementary school in Los Gatos was 

subjected to severe shaking, but damage was limited to nonstructural and contents shifting, except in one classroom wing, 

where ground heaving raised and cracked the floor slab, jamming a door and window shut. 

A San Francisco High School suffered severe structural cracking. 

This school was constructed in 1920 as an automobile manufacturing building and was structurally 

upgraded in 1947. Restoration costs 

were estimated at $10 million. Total 

restorations for the San Francisco 

school district were estimated to be 

$30 million; for Oakland, the district 

losses were $1.5 million. Though 

undamaged, an elementary school 

in San Francisco was closed because 

of the potential collapse of a nearby 

elevated freeway structure, which 

was considered a hazard to the 

building and its occupants. Hazards 

from unbraced and unanchored 

nonstructural items were evident in 

many buildings, including pendantmounted light fixtures, suspended 

acoustical ceilings, and unanchored 

furniture and contents such as filing 

cabinets and shelving.

In the Northridge, California, earthquake of 1994, state inspectors 

red-tagged 24 school buildings and 

yellow-tagged 82 school buildings, 

although this was later considered 

TAGGING

A post-earthquake evaluation procedure has been 

developed in California that employs colored 

placards, or “tags,” affixed to buildings, that show 

that the building has been inspected and indicate 

the level of safety. The colors of the tags and their 

safety level classification follow:

A red tag indicates UNSAFE: Extreme 

hazard, may collapse. Imminent danger 

of collapse from an aftershock. Unsafe 

for occupancy or entry, except by 

authorities.

A yellow tag indicates LIMITED 

ENTRY: Dangerous condition believed 

to be present. Entry by owner permitted 

only for emergency purposes and only 

at own risk. No usage on continuous 

basis. Entry by public not permitted. 

Possible major aftershock hazard.

A green tag indicates INSPECTED: 

No apparent hazard found, although 

repairs may be required. Original 

lateral load capacity not significantly 

decreased. No restriction on use or 

occupancy.
4-30 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

Figure 4-27 

Ceiling damage, 

Northridge, CA, 1994

SOURCE: GARY MCGAVIN, 

REDLANDS, CA

over-conservative. No structural elements collapsed. There was, 

however, considerable nonstructural damage that was costly to 

repair, resulting in the closure of a number of schools and, if the 

schools had been in session, would have caused casualties. The 

Field Act focused on structural design and construction, and 

only recently were nonstructural elements included in the scope 

of the Act (see Figures 4-27, 4-28, and 4-29).
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-31

Figure 4-29 

Line of suspended light 

fixtures fallen on teacher’s 

station, Northridge, CA, 

1994

SOURCE: EARTHQUAKE 

ENGINEERING RESEARCH INSTITUTE, 

OAKLAND, CA, AND GARY 

MCGAVIN, REDLANDS, CA

Figure 4-28 

Damage to ceramic kiln, including fractured gas 

line, Northridge, CA, 1994

SOURCE: GARY MCGAVIN, REDLANDS, CA
4-32 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

4.3.4 Consequences: Casualties, Financial Loss, 

and Operational Disruption

Casualties in California schools have been few and minor, 

primarily due to regulation by the Field Act and by chance. Significant Alaskan and California earthquakes, from Santa Barbara 

(1925) to Northridge (1984) have all occurred outside of school 

hours: therefore, the effects of a major earthquake when schools 

are fully occupied have not been experienced. In other regions, 

casualties have been few; in the Seattle earthquake of 1949, two 

school children died in Tacoma when bricks cascaded onto 

exit ways. The closure of Seattle schools for spring vacation had 

averted fatalities and serious injuries in similar building failures at 

a number of sites in the city.

The impact of school closure as a result of damage is the loss of 

public service and severe disruption for students, faculty, and staff. 

Ultimately, the taxpayer will pay the costs, but this is spread over 

the whole community, the state, and the Federal Government. 

Typically, schools are self-insured and do not purchase insurance on the private market. For a private school, closure means 

a serious loss of revenue; in addition to the costs of repair, the 

students may not return if the school is closed for a long period of 

time. Therefore, obtaining insurance may be a prudent measure. 

As with any of the natural hazards reviewed in this manual, an earthquake can close a school, keeping the school district from doing 

its main job (i.e., teaching students). The length of the closure will 

depend on the severity and types of damage. It may also depend on 

whether the building was fully insured or whether disaster assistance 

will be available quickly enough to allow speedy repairs and reconstruction. Sometimes repairs are put on hold, pending a decision on 

whether the building should be repaired or condemned.

There are also social and psychological factors, such as difficulties 

imposed on students, parents, faculty, staff, and the administration 

during the time the school is not usable. This is illustrated by the 

following quotation that, although it refers directly to hurricanes, 

also applies to earthquakes and other disasters. 
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-33

❍ “From the standpoint of children and families, after an impact is a particularly bad time for 

schools to be closed. Damaged homes and neighborhoods are dangerous and depressing 

places. Children are often left with no safe place to play when yards, playgrounds and 

recreational programs are lost, no one to play with when playmates and friends are forced to 

dislocate and parents are too busy dealing with survival and rebuilding issues to have much 

time for them.”

❍ “The closing of a local school is highly disruptive to social networks and, if it becomes 

permanent, can rob a neighborhood of its identity and cohesion. One of the most dramatic 

effects that can occur to a severely impacted community is when a school is closed for a long 

time, maybe even permanently, due to regional depopulation after homes are destroyed.”

❍ “Getting schools reopened quickly has been found to be an important step toward rebuilding 

the community as a whole.”

❍ “An understudied area is the long-term effect of major disasters on the education and 

development of children.”

❍ “The shock of being uprooted and moved to a new school, even temporarily, can be very 

difficult for children. The effects can be particularly traumatic if they occur at a critical 

developmental time, such as the senior year with its preparation for college and graduation 

festivities.”

SOURCE: THE HEINZ CENTER, HUMAN LINKS TO COASTAL DISASTERS, H. JOHN HEINZ III CENTER FOR SCIENCE, ECONOMICS 

AND THE ENVIRONMENT, WASHINGTON, DC, 2002

4.4 SCOPE, EFFECTIVENESS, AND 

LIMITATIONS OF CODES

Building design in the United States has typically been regulated by the provisions of one of three model building codes: 

the National Building Code (NBC), published by Building 

Officials and Code Administrators International (BOCA); the 

Standard Building Code (SBC), published by Southern Building 

Code Congress International (SBCCI); and the Uniform 

Building Code (UBC), published by International Conference 

of Building Officials (ICBO). The UBC tended to be most 

commonly adopted in the Western U.S., the NBC was used 

predominantly in the Northeast and Midwest, and the SBC was 

most commonly used in the South and Southeast. 
4-34 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

4.4.1 The Background of Seismic Codes

Seismic codes currently in use in the United States have been 

very highly developed since the initial regulations for the protection of buildings against earthquakes first appeared in the 

UBC in California in 1927. Beginning in the 1950s, the earthquake-resistant design provisions of the three model codes used 

as the basis for building regulation in the U.S. were based on 

recommendations developed by the seismology committee of 

the Structural Engineers Association of California (SEAOC) and 

contained in their publication known as the “Blue Book.” 

FEMA, one of the lead agencies in NEHRP, provided support for 

updating and continued development of a seminal document, 

ATC-3-06, produced by the Applied Technology Council (ATC), 

a non-profit research foundation set up after the San Fernando 

earthquake of 1978 to work on recommended improvements in 

the seismic building code. The ATC-3-06 document, now titled 

the NEHRP Recommended Provisions for Seismic Regulations for New 

Buildings and Other Structures, has been updated every 3 years 

since 1985. These provisions were adopted by the SBC in 1992 

and, in 1997, the seismic provisions of the UBC and NEHRP 

were combined. 

Depending on which code regulated the structural design, 

seismic design was conducted in accordance with one of two 

significantly different sets of provisions. Seismic design of structures under the UBC is governed by provisions developed by 

the SEAOC and structures designed under the NBC and the 

SBC are governed by somewhat different provisions developed 

by the Building Seismic Safety Council (BSSC) of the National 

Institute of Building Sciences (NIBS). Following a major effort 

by both groups, the 1997 editions of both the UBC and NEHRP 

Provisions resulted in a unification of these design approaches.

Meanwhile, after years of negotiation, all three model code 

entities have now consolidated their services, products, and operations into one member service operation, the International 
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-35

Code Council. The ICC first published a unified model building 

code, the International Building Code (IBC) in 2000, with revisions planned on a 3-year basis. The seismic provisions of the 

IBC are based primarily on the unified UBC/NEHRP provisions. 

Subsequently, however, the National Fire Protection Association has also developed a model building code, the NFPA 5000, 

Building Construction and Safety Code, first issued in 2002. The 

American Society of Civil Engineers (ASCE) published ASCE 

7 Minimum Design Loads for Buildings and Other Structures, which 

gives requirements for dead, live, soil, flood, wind, snow, rain, 

ice, and earthquake loads. ASCE 7 is referenced in the UBC, 

IBC, and NFPA model codes.

Thus the seismic codes are in a state of transition, and the intent of developing a single, nationally applicable model code 

has not yet been realized. Currently, jurisdictions are faced with 

continuing with one of the three original model codes, which 

will become increasingly out of date because they will no longer 

be revised and published, or adopting the IBC or NFPA 5000 

model codes. Some large municipal jurisdictions will continue 

to produce their own codes, which will be derived from some 

combination of the model codes. 

As noted above, seismic codes have the primary purpose of 

establishing the minimum lateral forces for which buildings 

must be designed. To do this, the code provides an equation, in 

which the vibrating seismic forces are represented by a single 

static force, called the “base shear,” applied at the base of a 

building. Variables in the equation enable the designer to adjust the design force for varying site seismicity, alternative soil 

conditions, different structural and nonstructural systems and 

materials, different building heights, and occupancies of varying 

importance. 

In addition, the codes have a number of provisions that deal 

with the detailed design of some building components, such 

as reinforcing steel in concrete structures and welding in 

steel structures. Because the actual forces on the building are 
4-36 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

estimated in a very simplified manner, a large safety factor is introduced, so that the design forces tend to be over-estimated.

4.4.2 Seismic Codes and Schools

Seismic codes are concerned primarily with types of structures and there are a few provisions that relate to specific 

occupancies. The IBC categorizes school buildings as Type II: 

“...buildings and other structures that represent a substantial 

hazard to human life in the event of failure...” Type II buildings are assigned an Importance Factor of 1.25. This means that 

the seismic force calculated by use of the Equivalent Lateral 

Force procedure would be multiplied by 1.25 so that schools are 

designed to a higher standard than ordinary buildings. 

As previously mentioned, in California, K-12 schools are regulated by the Field Act, which is the only significant legislation 

that singles out the design and construction of schools to resist 

earthquakes and is an important model. However, the Field Act 

is not a code; it requires that schools be designed by a licensed 

architect or structural engineer, that plans and specifications be 

checked by a special office of the Department of the State Architect, and that independent testing and inspection be conducted 

during construction. The Greene/Garrison Act of 1976 made 

the Field Act provisions retroactive and required that all nonconforming schools be brought up to the current code level. 

Implementing the nonstructural provisions of the seismic code 

will significantly reduce damage to the nonstructural components and reduce the possibility of closing the school because of 

ceiling and lighting damage, partition failures, and loss of essential utilities. In this instance, the code goes somewhat beyond 

the structural objective of only reducing the risk of casualties. 

However, this is an important issue for schools, for recent experience in earthquakes has shown that nonstructural damage to 

schools is dangerous to the occupants, costly to repair, and operationally disruptive.
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-37

4.4.3 The Effectiveness of Seismic Codes 

Building codes originated in the effort to reduce risk to 

health and safety, rather than reducing property loss, but, as 

they evolved, they indirectly and directly assisted in reducing 

building damage. They establish the minimum standards for 

safety commensurate with affordability and other impacts such 

as measures that might create extreme inconvenience to occupants or seriously reduce the building’s functional efficiency.

Among engineers, there is general agreement that, based on 

California’s earthquake experience, regulation through a properly enforced seismic code has largely fulfilled the intent of 

ensuring an acceptable level of safety against death and injury. 

The performance of school buildings in recent California earthquakes substantiates this; structural damage has been minimal 

in the more recently designed schools. Application of the Field 

Act ensures that schools are designed and constructed to more 

rigorous standards than most other buildings. 

Some qualifications, however, follow:

❍ Even in California, the standards of code enforcement vary 

considerably, and smaller jurisdictions may not have trained 

engineering staff to conduct effective plan checks and 

inspections. 

❍ The nonstructural provisions of the seismic codes are 

often not adopted at the local level. Even in California, 

nonstructural components have not been regulated to the 

same level of care as structural components, and have been 

the cause of considerable economic loss and disruption of 

operation. 

❍ In regions of moderate earthquake risk that have recently 

introduced seismic design regulation, the code may be 

misinterpreted and design errors made due to inexperience 

of both designers and building officials.
4-38 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

4.5 EVALUATING EXISTING SCHOOLS FOR 

SEISMIC RISK AND SPECIFIC RISK 

REDUCTION METHODS

A set of well developed procedures exists for the seismic 

evaluation of buildings, and a number of FEMA-sponsored publications are available to assist in the evaluation process. These 

guides have been developed since the 1980s and have been used 

extensively. However, this section also provides a simple seismic 

evaluation checklist that focuses specifically on schools.

The procedures are listed below in the order in which they 

would be used, starting with a simple screening process. 

4.5.1 Rapid Visual Screening

The Rapid Screening Procedure (RSP) was published in FEMA 

154, Rapid Visual Screening of Buildings for Potential Seismic Hazards: a Handbook. The procedure is intended as an initial step in 

identifying hazardous buildings and their deficiencies. Buildings identified by this procedure to be potentially hazardous 

must be examined in more detail by a professional engineer experienced in seismic design. Because this screening is aimed at 

providing a low cost method of identifying large inventories of 

potentially hazardous buildings for public and private owners, 

and thus reducing the number of buildings that should be 

subject to a more detailed evaluation, it is designed to be performed from the street without benefit of entry into a building. 

The screening process can be completed in 20-30 minutes for 

each building. In some cases, hazardous details may not be visible, and seismically hazardous structures will not be identified 

as such. Nonstructural interior components are not evaluated. 

Conversely, buildings identified as potentially hazardous may 

prove to be adequate.

Typically, a school district will not be faced with the problem of 

lack of building access and the RSP procedure is most useful for 
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-39

large school districts, municipalities, or even states that wish to 

get an economical preliminary evaluation of the seismic risks 

faced by their school inventory. The procedure is not intended 

to provide a definitive evaluation of the individual buildings. 

The methodology is based on a visual survey of the building 

and a data collection form used to provide critical information. 

The collection form includes space for sketches and a photo of 

the building as well as pertinent earthquake-safety related data. 

The FEMA handbook for the procedure provides the inspector 

with background information and data required to complete 

the form (see Figure 4-30). The procedure is designed to be 

usable by people with some knowledge of buildings who are 

not necessarily professional architects or engineers or familiar 

with seismic design. It has been successfully applied by architectural and engineering students. The methodology enables 

the inspector to identify significant seismic-related defects and 

to arrive at a numerical score, with a hazard ranking of 1-6 (see 

Figure 4-30).

The ranking of surveyed buildings can be divided into two categories: those acceptable as to risk to life safety or those that 

may be seismically hazardous and should be studied further. A 

score of 2 is suggested as a “cut-off” based on current seismic 

knowledge (i.e., if a building has a structural “score” of 2 or less, 

it should be investigated by a structural engineer experienced in 

seismic design).
4-40 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

Figure 4-30 Example of rapid visual screening information form

SOURCE: JORDAN SCHOOL DISTRICT, SANDY, UT, RANDY HASLAM
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-41

4.5.2 Systems Checklist for School Seismic 

Safety Evaluation

Table 4-2 represents a simplified version of the FEMA 178/310 

Evaluation Procedure; also see Section 4.5.3. This version focuses on structural and nonstructural systems and components 

that will be found in schools. The data are organized on a systems basis and are designed to establish whether the building is 

a potential seismic hazard and, if so, what its specific vulnerabilities are. Use of the checklist requires some seismic engineering 

knowledge, but the information can be obtained by inspection 

and no engineering calculations are necessary. The checklist 

can be used in conjunction with the RSP procedure, and will 

augment the RSP analysis because it assumes that the building 

will be accessible and design drawings are available. Both of 

these conditions are likely to be met in evaluating a public 

school building.

The checklist can also be useful in interdisciplinary discussions 

between consultants and school district personnel, and can assist in fee negotiation with the client. 
4-42 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

Table 4-2: School Seismic Safety Evaluation Checklist

 Configuration

Is the architectural/structural 

configuration regular?

Irregular vertical and horizontal 

configurations, such as re-entrant 

corners and soft first stories, may lead to 

significant stress concentrations.

FEMA 178, Section 3.7

FEMA 273, Section 2.7.1

System

Identifier Evaluation Question

Evaluation

Y or N or 

comment

Guidance Data References

1 Site

Is there is an active fault on 

or adjacent to the site? 

If suspected, site-specific geologic 

investigations should be performed.

Local building department, state 

geologist, local university, or local 

geotechnical consultant

Does the site consist of stiff 

or dense soil or rock?

If softer soils that can lead to force 

amplification are suspected, site-specific 

geologic investigations should be 

performed.

Local building department, state 

geologist, local university, or local 

geotechnical consultant 

Are post-earthquake site 

egress and access secured? 

Alternative routes, unlikely to be blocked 

by falling buildings, power lines, etc., are 

desirable.

Inspection by district personnel/architect

Are utility and 

communications lifelines 

vulnerable to disruption and 

failure?

Security of the entire utility and 

communications network is the issue: 

the school may be impacted by off-site 

failures.

Inspection on site by district personnel 

and Mechanical/Electrical/Plumbing 

(M/E/P) consultants. For off site, 

contact local power and communications 

providers.

Are there alternate or 

backup sources for vital 

utilities?

Increase the probability of the school 

remaining functional after an event, 

particularly if the school is used for postearthquake shelter.

Inspection and district personnel, M/E/P 

consultants, and local utility suppliers

Are building setbacks 

adequate to prevent 

battering from adjacent 

buildings?

Inadequate spaces between building 

walls may occur in dense urban settings.

FEMA 178, Section 3.4

FEMA 273, Section 2.11.10

Is there adequate space 

on the site for a safe and 

“defensible” area of refuge 

from hazards for building 

occupants?

Outside spaces can be used as safe postearthquake assembly areas for school 

occupants and possibly the community. 

Inspection district personnel/architect/

local emergency staff

2 Architectural
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-43

 Planning and Function 

Are exit routes, including 

stairs, protected from 

damage and clear from 

nonstructural elements or 

contents that might fall and 

block exit ways? 

Schools sometimes have large unbraced 

lockers in hallways, or store other 

materials, such as tall filing cabinets or 

bookcases, that may block exits.

Inspection by district personnel

FEMA 274, Section C11.94.4

 Ceilings

Are light suspended grid 

ceilings braced and correctly 

attached at walls?

Grid ceilings easily distort (particularly in 

light and flexible frame structures), thus 

causing ceiling panels to fall.

FEMA 274, Section C11.9.4

Are heavy plaster suspended 

ceilings securely supported 

and braced?

Heavy lath and plaster ceilings in older 

schools are very dangerous if poorly 

supported. 

FEMA 274, Section C11.9.4.4

 Partitions and Space Division

Are partitions that terminate 

at a hung ceiling braced to 

the structure above? 

Partitions need support for out-of-plane 

forces and attachment to a suspended 

ceiling grid is inadequate. 

FEMA 178, Section 10.5.2

FEMA 273, Section 11.9.2.4

Are masonry or hollow 

tile partitions reinforced, 

particularly those 

surrounding exit stairs?

Heavy partitions attract strong 

earthquake forces because of their 

stiffness and mass, and are prone to 

damage. They are particularly dangerous 

around stairs and exit ways.

FEMA 273, Section 11.9.2.4

 Other Elements

Are exterior entrance 

canopies and walkways 

engineered to ensure no 

collapse?

Post-earthquake safety of these 

structures is critical to ensure safe exiting 

after an event. Also, at certain times 

they may be used as gathering places 

and be densely occupied. 

FEMA 273, Section 11.9.6

Are parapets, appendages, 

etc., securely attached 

and braced to the building 

structure?

Unreinforced masonry parapets are 

especially vulnerable. Also include items 

such as cornices, signs, large satellite 

communication “dishes.”

FEMA 273, Section 1.9.5

Are heavy lockers, library 

shelves, and vertical filing 

cabinets that could fall 

on people braced to the 

structure?

These can topple and injure occupants, 

and also block exit ways.

FEMA 178, Section 10.9.5

Table 4-2: School Seismic Safety Evaluation Checklist (continued)

System

Identifier Evaluation Question

Evaluation

Y or N or 

comment

Guidance Data References
4-44 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

Table 4-2: School Seismic Safety Evaluation Checklist (continued)

3 Structural System

Is there a continuous load 

path from the foundation to 

the roof?

This is an important characteristic to 

ensure good seismic performance. This 

also sometimes relates to irregularity in 

configuration.

Engineer to check design of school 

structure

Does the structure provide 

adequate redundancy in the 

event of the loss of some 

structural supports?

Short spans with many vertical supports 

are desirable, but long spans are 

sometimes necessary and require special 

care in design. 

FEMA 178, Section 3.1

Is all load-bearing structural 

masonry reinforced 

according to code?

Unreinforced masonry has limited 

ductility and therefore cannot withstand 

large earthquake-induced repetitive 

displacements.

Engineer to check against local code 

requirements

Is the structure’s reinforced 

concrete designed to seismic 

code later than 1976?

The reinforced concrete codes changed 

in 1976, and structures designed before 

these codes were adopted may be 

inadequate.

Check date of design, and edition of code 

used

Is the structure’s wood 

frame well maintained, with 

little or no deterioration?

Wood framing is subject to attack by 

termites and water damage, which may 

seriously weaken the structure.

School district personnel to inspect

Are horizontal structural 

members securely connected 

to walls and columns?

Good connections between all structural 

members are very important for 

structural integrity.

Structural engineer to check

FEMA 178, Chapter 8

Are horizontal diaphragms 

correctly designed and 

constructed with necessary 

chords and collectors?

Large diaphragm openings and the 

edges of diaphragms need careful design 

to ensure forces are properly transmitted 

to walls and frames.

Structural engineer to check

FEMA 178, Chapter 7

System

Identifier Evaluation Question

Evaluation

Y or N or 

comment

Guidance Data References

4 Building Envelope

 Wall Cladding

Is the building cladding 

attached to structural 

frames so that it can 

accommodate drift?

Frames are flexible and cladding must be 

detailed to accommodate calculated drifts 

and deformations.

FEMA 273, Section 11.1.9.4
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-45

Are heavy veneer facing 

materials such as brick or 

stone securely attached to 

the structural walls?

Shear wall structures are very stiff and 

carry large earthquake forces; heavy 

attachments must be securely attached. 

Structural engineer to check design and 

field condition

Are heavy roofing materials 

such as tile and slate 

securely attached to the 

structure?

Installation of these materials over points 

of egress may be dangerous.

IBC Table 1507.3.7

Glazing

Are glazing and other 

panels attached so that they 

can accommodate drift? 

Glazing must be installed with sufficient 

bite, and adequate space between glass 

and metal. 

FEMA 274, Section C11.9.1.5

Is the glazing material 

inserted into a surrounding 

structure that limits drift 

and racking?

Glazing is dependent on the surrounding 

structure to limit racking.

Structural engineer to inspect framing 

and structural conditions

Table 4-2: School Seismic Safety Evaluation Checklist (continued)

System

Identifier Evaluation Question

Evaluation

Y or N or 

comment

Guidance Data References

5 Utilities

Are building utility 

distribution systems well 

supported and adequately 

braced?

Flexible connections may be necessary 

where utilities enter the building.

FEMA 273, Section 11.10.8

6 Mechanical

Is heavy mechanical 

equipment adequately 

secured and isolators 

provided with snubbers? 

Spring isolated equipment must be 

restrained from jumping off isolators. 

FEMA 174, Section 11.10.1

Is the heating piping properly braced and provided 

with expansion joints? 

Increase likelihood of continued postevent function.Inspection by school district personnel 

and M/E/P consultants

Is ductwork properly 

supported and braced? 

Increase likelihood of continued postevent function.Inspection by school district personnel 

and M/E/P consultants

Are water heaters and other 

tanks securely braced?

Gas heaters or tanks with flammable or 

hazardous materials must be secured 

against toppling.

FEMA 174
4-46 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

7 Plumbing

Are plumbing lines 

adequately supported and 

braced?

Protection of joints is especially 

important.

FEMA 174, Section 11.10.3

Is fire protection piping 

correctly installed and 

braced?

Increase likelihood of continued postevent function.Inspection by school district personnel and 

M/E/P consultants

Are ducts and piping that 

pass through seismic joints 

minimized and provided 

with flexible connections?

Differential movement between sections 

of the building can cause breakage and 

leaks in pipes and ducts if no provision 

is made for movement. If walls at joint 

are firewalls, penetrations should be 

fireproofed.

FEMA 174

Table 4-2: School Seismic Safety Evaluation Checklist (continued)

System

Identifier Evaluation Question

Evaluation

Y or N or 

comment

Guidance Data References

8 Electrical

Are suspended lighting 

fixtures securely attached, 

braced, or designed to sway 

safely?

Older suspended lighting fixtures have 

performed badly in earthquakes and are 

an injury hazard.

FEMA 174

FEMA 273, Section 11.10.9.1

Are light fixtures supported 

in an integrated ceiling, 

braced, and provided with 

safety wires?

Light fixtures within a grid often fall 

when the grid is distorted, unless the 

fixtures are secured with safety wires.

FEMA 174

FEMA 273, Section 11.10.4.1

Is heavy electrical 

equipment adequately 

secured? 

Switch gear and transformers are heavy 

and failure can shut down the electrical 

system. 

FEMA 273, Section 11.10.7

9 Fire Alarm

Is the fire alarm system 

connected to a secondary 

power supply? 

This is also necessary to support daily 

operational needs, including lighting, 

heating, communications, etc., and also if 

the building is used as a post-earthquake 

shelter.

Inspection by district maintenance 

personnel and M/E/P consultants 

Is the fire alarm system 

provided with a battery 

backup system capable of 

operating the system for 24 

hours after power loss?

Required by code even if the building will 

not be used after an event, so that the 

school can be evacuated.

Inspection by district maintenance 

personnel and M/E/P consultants
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-47

Table 4-2: School Seismic Safety Evaluation Checklist (continued)

System

Identifier Evaluation Question

Evaluation

Y or N or 

comment

Guidance Data References

10 Communications and IT Systems

Are communications 

components adequately 

braced and supported?

Post-event communications are vital 

for issuing instructions to school 

administrators, students, faculty, and 

staff. Some components, such as large 

satellite dish antennas, are easily 

damaged if not properly supported.

FEMA 273, Section 11.10.8

Are building intercom 

systems connected to a 

standby generator? 

Necessary to enable continued use of 

utility power, whether earthquake-caused 

or not.

Inspection by maintenance personnel and 

M/E/P consultants

11 Equipment Operations and Maintenance

12 Security Systems

13 Security Master Plan

4.5.3 The NEHRP Handbook for the Seismic 

Evaluation of Existing Buildings 

(FEMA 178/310) 

For those buildings that, as the result of a preliminary screening, 

are candidates for a more detailed investigation, the BSSC developed a procedure for the systematic evaluation of any type of 

building (FEMA 178 and 310, The NEHRP Handbook for the Seismic 

Evaluation of Existing Buildings). This procedure can be used to 

evaluate the structural and nonstructural systems and components 

for any type or size of individual school building. However, the 

procedure focuses on evaluating whether the building is a potential earthquake-related risk to human life posed by the building 
4-48 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

or a building component. The procedure does not address code 

compliance, damage control, or other aspects of seismic performance not related to life safety.

The handbook methodology involves the use of two sets of 

questions: one set addresses the characteristics of 15 common 

structural types and the other, instead of addressing complete 

structural systems, deals with structural elements, foundations, 

geologic site hazards, and nonstructural components and systems. These questions are designed to uncover the flaws and 

weaknesses of a building, and are in the form of positive evaluation statements describing building characteristics that are 

essential if the failures observed in past earthquakes are to be 

avoided. The evaluating architect or engineer should address 

each statement and determine whether it is true or false. True 

statements identify conditions that are acceptable and false statements identify conditions in need of further investigation. The 

handbook also specifies a process for dealing with statements 

that are found to be false. 

The evaluation requires some basic structural calculations and a 

site visit and follow-up field work will be necessary. The primary 

product of the evaluation is the identification of weak links in 

the building that could precipitate structural or component 

failure. Although the procedure will provide guidance on structural deficiencies, it is not intended to identify appropriate 

seismic retrofit options. The design engineer needs to understand the overall deficiencies of the building before attempting 

to identify retrofit design approaches. The overall deficiencies 

may be due to a combination of component deficiencies, inherent adverse design, construction failures, deterioration, or a 

serious weak link. 

4.6 EARTHQUAKE RISK REDUCTION 

METHODS

Although the general principles of design are similar for new or 

existing schools, there are differences in code requirements and 
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-49

overall project delivery processes that reflect the design freedoms 

of new buildings and the constraints of existing ones. 

Engineering of structural and nonstructural risk reduction 

methods is similar for new and existing schools. New school 

design offers the possibility of construction on a site subject to 

less ground motion because of better soil conditions or further 

proximity to a fault. It can be designed with the most appropriate 

structural system, using known and tested materials and a good 

building configuration. These possibilities are not available when 

retrofitting an existing school; the building may have been designed to an obsolete seismic code or no code at all, its materials 

may be questionable, and the building configuration and structural system may be inappropriate. Therefore, the protection of 

an existing school must start with a careful evaluation of its vulnerability. Seismic retrofitting is expensive and time-consuming; 

however, the adoption of an incremental retrofit procedure, as 

described in Section 4.6.2, can help to keep time and cost within 

reasonable limits. 

4.6.1 Risk Reduction for New Schools

Methods of design for earthquake protection involve three main 

aspects of the school: its site, its structure, and its nonstructural 

components. 

In terms of risk reduction, the first priority is the implementation 

of measures that will reduce the risk of casualties to students, staff, 

and visitors. The second priority is the reduction of damage that 

leads to downtime and disruption. The third priority is the reduction of damage and repair costs.

Alternative measures to achieve these objectives are as follows, in 

ascending order of cost:

❍ New Schools Regulated by Seismic Codes

• Provide personal protection training.
4-50 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

• Evaluate code provisions against risk priorities. Evaluate 

whether design to current code will meet acceptable risk 

objectives for damage costs and reduction of downtime.

• Consider adopting California’s Field Act model for quality 

control of design and construction; can be administered 

by a single district with specification provisions for 

inspection in contract documents. 

• Use performance-based design procedures if code-based 

design does not meet acceptable risk objectives.

❍ New Schools Not Regulated by Seismic Codes

• Provide personal protection training.

• Design to appropriate code standards on a voluntary basis.

• Use performance-based design procedures to meet 

acceptable risk objectives.

• Consider adoption of seismic code; requires communitywide cooperation.

Damage reduction is common to all the objectives. The following 

sections give an overview of the design strategies that are used to 

achieve acceptable levels of protection in new schools.

School Sites. Protection of schools and their occupants from 

earthquakes depends on correct seismic design and construction 

to resist the estimated earthquake forces that the building could 

encounter at its site. Because ground motion from a single earthquake may vary considerably, depending on the nature of the soil 

and the distance of the building from known earthquake faults, 

careful site selection is a critical first step in reducing the forces 

on the building, although a single school site or a small district 

will rarely have this option. School sites are generally selected 

based on factors such as availability, served student population, 

cost, convenience of access for the school students and staff, and 

general demographic concerns rather than seismicity. However, a 

large district that is developing a multi-school plan of new facilities 
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-51

In the late 1960s, the small school 

district of Portola Valley, California, 

was faced with declining enrollment for 

its intermediate school, which was also 

outdated. In addition, the school was 

located very close to the San Andreas 

Fault. Concerned about seismic risk, 

the district deemed the site unsuitable 

for school purposes and sold the site to 

the city for 1 dollar, which used it for 

recreational purposes.

should include recognition of any natural hazard vulnerabilities as 

a factor in the evaluation of alternative sites. A school district can 

reduce its seismic vulnerability by reducing the intensity of earthquake shaking to be expected at a site over the life of the building. 

There are several ways in which this can be accomplished:

❍ Locate the building in an area of lower seismicity, where 

earthquakes occur less frequently or with typically smaller 

intensities. Although it would be very rare for a school district 

to make a site selection decision based solely on seismic risk, 

moving a school even a few miles in some cases can make a big 

difference to its seismic hazard, such as locating a school within 

1 mile of a major fault versus being 5 to 10 miles away from it.

❍ Locate the building on a soil type that reduces 

the hazard. Local soil profiles can be highly 

variable, especially near water, on sloped 

surfaces, or close to faults. In an extreme case, 

siting on poor soils can lead to liquefaction, 

land sliding, or lateral spreading of the soil. 

Frequently, similar buildings located less than 

1 mile apart have performed in dramatically 

different ways because of differing soil 

conditions in earthquakes. Even when soilrelated geologic hazards are not present, 

earthquake motions that have to travel through 

softer soils will be amplified more than those 

traveling through firm soils or rock. If general knowledge of 

site conditions is a concern, the effects of soil hazard on risk 

should be determined by the use of geotechnical and structural 

engineers to assess the potential vulnerabilities associated with 

differing site conditions. Variables in vulnerabilities should be 

weighed against the costs, both direct and indirect, of locating 

the facility on soils that will result in better performance.

❍ Engineer the building site to increase building performance 

and reduce vulnerability. If building relocation to an area of 

lower seismicity or to an area with a better natural soil profile 
4-52 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

The ELF equation in the IBC is V=Cs

W, where V= the shear, or pushing, 

force at the base of the building, 

which represents the total earthquake 

force on the building, Cs is a 

coefficient representing the estimated 

site acceleration (derived from maps 

provided in the code), modified by 

factors related to the characteristics 

of the structure, the importance of 

the building, and the nature of the 

soil. W is the weight of the building. 

This equation is the same as Sir Isaac 

Newton’s equation in his second 

law of motion, F=MA (Force = Mass 

times Acceleration), with some added 

modifiers. 

is not a cost-effective option, the soil at the designated site can 

sometimes be treated to reduce the hazard. For example, on a 

liquefiable site, the soil can be grouted or otherwise treated to 

reduce the likelihood of liquefaction occurring. Soft soils can 

be excavated and replaced, or combined with foreign materials 

to make them stiffer. Alternatively, the building foundation 

itself can be modified to account for the potential effects of 

the soil, reducing the building’s susceptibility to damage even 

if liquefaction or limited land sliding does occur. The school 

board should weigh the additional costs of modifying the soil 

characteristics or the building foundation with the expected 

reduction in damage and loss. However, because most schools 

are one or two stories in height, site area usage is considerable, 

and site treatment is likely to be costly.

In most cases, it is probable that a designated school site will be accepted. Proposed construction directly over a fault is probably the 

only location characteristic that would lead to rejection of an otherwise suitable site. The forces for which the school must be designed 

are also increased if it is in close proximity of a 

fault, which will increase the structural cost. Sites 

are assigned to one of six categories, from A, which 

represents hard rock, to F, which represents soils 

vulnerable to potential failure or collapse such as 

liquefiable soils, sensitive clays, and weak soils and 

clays. Variations in soil type are covered by increasing 

or decreasing the design forces by application of 

a coefficient within the calculation of the Equivalent Lateral Force (ELF) equation, which is used to 

establish the design lateral forces on the building. 

The ELF procedure assumes a soil type B. For 

categories A through E, design forces must be 

modified by application of a coefficient, or multiplier. For Category A soils, the multiplier is 0.8 (i.e., 

the values are reduced). For Category E soils, the 

multiplier can be as high as 2.5 for short-period 

buildings such as schools. For buildings located on 
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-53

type F soils, a site-specific geotechnical investigation must be performed to establish design values.

Reducing Damage to School Structures. Minimum standards and 

criteria for structural design are defined in the seismic codes. 

The codes provide maps that show whether the location is subject to earthquakes and, if so, the probability of occurrence, 

expressed by varying levels of seismic forces for which a building 

must be designed. Seismic codes are adopted by state or local 

authorities, so it is possible for a seismically-prone region to be 

exempt from seismic code regulations if the local community 

feels that the adoption of a seismic building code is not desired. Based on historic and scientific data, although the seismic 

hazard exists, some communities may choose to ignore the risk, 

because no one has experienced an earthquake in their lifetime. 

Such a policy should be of serious concern to school district officials, the local school board, and parents. 

This is a difficult issue because, although the risk may appear to 

be minimal, the effects could be catastrophic if a significant event 

were to occur. The very fact that such an event is rare means that 

the community may have no history of design for earthquakes 

and the building stock will be especially vulnerable. School buildings are an important community resource (along with other 

essential buildings such as hospitals, and fire and police stations) 

that should not gamble on the avoidance of a rare event. 

Because of systematic observation of earthquake damage to buildings 

and extensive analytical and experimental research, seismic design in 

the 20th century has become a highly developed technology. 

Reducing structural damage in earthquakes depends on:

❍ The correct application of code criteria and analytical 

methods. Seismic codes have become increasingly complex 

and a high standard of care and engineering judgment is 

necessary to ensure correct application. 
4-54 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

❍ The correct selection and application of structural systems 

and materials. Different structural systems have varied 

characteristics that must be matched to the nature and 

purpose of the school. Flexible planning, for example, implies 

the use of a frame structure rather than relying on shear walls 

that may impact planning freedom. 

The following two graphics show the basic types of structural 

lateral force resisting systems.

SOURCE: BSSC: PRESENTATIONS TO THE ARCHITECTURAL COMMUNITY, 2001, CHRIS ARNOLD AND TONY ALEXANDER

HOW BUILDINGS RESIST EARTHQUAKES

Lateral Force Resisting Systems – 

Basic Types

This figure shows the basic types of lateral 

force resisting structural systems. They tend 

to be mutually exclusive (i.e., it is desirable 

not to mix the systems in a single building 

because of the different strength and stiffness 

characteristics of the systems). Shear walls are 

very stiff while moment-resistant frames are 

flexible. Braced systems are in between.

The systems have major architectural 

implications. Shear walls, which should run 

uninterrupted from foundation to roof, may 

impose major planning constraints on a 

building. Moment frames create unobstructed 

floors, but, because of their special 

connection requirements, are expensive. 

They are subject to more deformation that 

may result in costly damage to nonstructural 

components and systems. Braced frames are 

a common compromise.

Diaphragms

Together with the lateral force resisting 

system, diaphragms form a horizontal 

system that connects the vertical 

elements and carries their loads down 

to the foundation. Large openings in 

the diaphragm may limit its ability to be 

effective in transferring forces.
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-55

❍ The correct design of critical elements such as frames, 

shear walls, and diaphragms and their connections to 

one another: earthquake forces search out the weak links 

between structural members. Serious damage and collapse 

is often initiated by connection failure. These are the critical 

elements that provide seismic resistance; they must be 

correctly sized, located, and detailed. 

❍ Careful attention to key structural design principles such as 

provision of a direct load path and structural redundancy. 

❍ The correct design of the connections between structural 

elements and nonstructural components. 

❍ Configuration of the building (its size and shape) to be as 

simple and regular as planning and aesthetic requirements 

permit. Experience has shown that certain building shapes 

and architectural design elements contribute to bad seismic 

performance and need expensive structural design methods 

to make them achievable. 

❍ A high level of quality control to ensure that the building is 

properly constructed. Careful seismic design is valueless if 

not properly executed.

❍ A high level of maintenance to ensure that the building 

retains its integrity over time. Corrosion of steel and termite 

infestation or dry rot in wood can seriously affect structural 

integrity.

The following graphics show some problems caused by irregular 

building configurations.
4-56 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

SOME TYPICAL DESIGN PROBLEMS

Torsional Forces

This figure shows how torsion occurs. 

If the center of mass and center of 

resistance do not coincide, the building 

tends to rotate around the center of 

resistance.

Stress Concentrations

Stress concentration means that an 

undue proportion of the overall forces 

is concentrated at one or a few points 

of the building such as a particular set 

of beams, columns, or walls. These 

few members may fail and, by a chain 

reaction, bring down the whole building.

Soft Stories

This figure shows the failure mechanism 

of a soft or weak story. A regular 

building with equal floor heights will 

distribute its drift equally to each floor 

so that each is subjected to manageable 

drift. In the soft story building, the overall 

drift is the same, but the second floor 

connections are subject to all, or almost 

all, the drift and a failure mechanism is 

created.

SOURCE: BSSC: PRESENTATIONS TO THE ARCHITECTURAL COMMUNITY, 2001, CHRIS ARNOLD AND TONY ALEXANDER
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-57

TORSIONAL FORCES AND STRESS CONCENTRATION

Re-entrant Corners

Buildings with re-entrant corners (L-shape, 

U-shape, etc.) are subject to torsion and 

stress concentrations. Special design 

measures are necessary to counteract 

these tendencies. 

Soft Stories

Typical examples of soft story-induced 

damage. 

SOURCE: BSSC: PRESENTATIONS TO THE ARCHITECTURAL COMMUNITY, 2001, CHRIS ARNOLD AND TONY ALEXANDER

Reducing Damage to Nonstructural Components and Systems. 

Nonstructural components and systems are defined as those 

elements that do not contribute to the seismic resistance of the 

building (see Figure 4-31). They typically comprise from 75 to 

80 percent of the total school building by value, and they transform the structure into a working environment that provides 

weather protection, heating, cooling, lighting, and acoustic 

control. Damage to these components can be costly and render 

the building functionally useless even if the building structure 
4-58 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

performs in accordance with the intent of the seismic code. Nonstructural components are generally broadly classified as:

❍ Architectural

• Exterior envelope - opaque or glazed, roof and wall coverings

• Veneers

• Interior partitions

• Ceilings

• Parapets and appendages (e.g., signs and decorative 

elements) 

• Canopies and marquees

• Chimneys and stacks

❍ Mechanical 

• Boilers and furnaces

• HVAC source equipment and distribution components

❍ Electrical and Electronic

• Source power equipment and distribution components

• Source communications equipment and distribution 

components

• Light fixtures 

❍ Plumbing

• Storage vessels and tanks

• Piping systems 

• Hazardous materials distribution

❍ Furnishings and Interior Equipment 

• Bookcases, filing cabinets, and other storage 

• Shop and art equipment 

• Hazardous materials (HazMat) storage
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-59

Reduction of damage to nonstructural components depends on 

using methods of supporting and bracing the components to 

prevent failure (see examples in Figures 4-32, 4-33, 4-34, and 4-35). 

Seismic codes provide the design force for which the above components must be designed, together with a number of specific 

design requirements that must be followed. 

Figure 4-31 

The structural and nonstructural components. The upper graphic shows the building structure. 

The lower graphic shows the addition of the main nonstructural components.
4-60 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

Figure 4-33 

Bracing tall shelving to the 

structure

Figure 4-34 

Connection of nonstructural 

masonry wall to structure 

to permit independent 

movement

Figure 4-32 Suspended ceiling and light fixture bracing and support
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-61

Figure 4-35 

Bracing for existing 

unreinforced masonry 

parapet wall

4.6.2 Risk Reduction for Existing Schools

Procedures and Design Strategies. Additions to an existing 

school must meet all of the code requirements for a new 

building. There is currently no seismic code that applies to the 

retrofit of existing schools. Typically, the standards to be applied 

are derived from the code for new buildings and negotiated 

with the applicable building department. It is generally recognized that it is difficult or almost impossible to bring an existing 

structure up to full compliance with a current code and so some 

compromises have to be made; there is, however, no general 

agreement as to how the code for new buildings is applied to the 

retrofit design of existing ones. 

Reducing the seismic risk for an existing building requires the 

same general design principles as those necessary for a new 

building, but the architect and engineer are faced with existing 

structural and nonstructural systems and materials that may be far 

from ideal and, as previously stated, to bring them up to the standard of a new building could be difficult or almost impossible. 

The process should begin with an evaluation procedure similar 

to those outlined in Section 4.5. If the result of these evaluations 

is the need to retrofit an existing school or schools, the NEHRP 
4-62 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

Guidelines for the Seismic Rehabilitation of Buildings (FEMA 273) is 

the authoritative source document and can be used to help a 

school district select seismic protection criteria. The architect 

and engineer can also use the document for the design and 

analysis of seismic retrofit projects. 

FEMA 273 adopted the approach of providing methods and 

design criteria to achieve several different levels and ranges of 

seismic performance (unlike a conventional code that implies, 

but does not define, a single performance level). In doing 

this, the document shows that there is always the possibility of 

damage in a seismic event and the term “seismic performance” 

refers to the nature and extent of damage that the building exhibits. FEMA 273 provides a thorough and systematic procedure 

for performance-based seismic design, intended to result in the 

development of a design that targets achieving the owner’s level 

of acceptable risk within the owner’s available resources. 

The performance-based design approach outlined in FEMA 273 

provides uniform criteria by which existing buildings may be 

retrofitted to attain a wide range of performance levels, when 

subjected to earthquakes of varying severities and probabilities 

of occurrence. The process starts by requiring that the user select specific performance goals as a basis for design. In this way, 

users can directly determine the effect of different performance 

goals on the design requirements, including their complexity 

and cost. 

Typical design strategies for improving the protection of an existing school include (see Figure 4-36):

❍ Modifying and improving local components or materials, 

such as beam/column connections. This involves retrofitting 

connections and strengthening structural members by such 

methods as adding reinforcing or replacing them with new 

components.
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-63

Figure 4-36 

Design strategies for 

seismic retrofit of existing 

buildings

SOURCE: BUILDINGS AT RISK: 

SEISMIC DESIGN BASICS FOR 

PRACTICING ARCHITECTS, 

AIA/ACSA COUNCIL ON 

ARCHITECTURAL RESEARCH, 

WASHNIGTON, DC, 1994, ERIC 

ELSESSER
4-64 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

❍ Removing or reducing configuration irregularities. This involves 

providing seismic separations in irregular configurations or 

adding shear walls or bracing to reduce torsional effects, thereby 

strengthening and/or stiffening the entire structural system. This 

is a major retrofit that involves adding bracing or shear walls, 

replacing many structural members. 

❍ Reducing the mass of the building (to reduce forces). 

This involves changing the location of heavy items (e.g., 

bookcases) within the building, but would not apply to a onestory building, except where a tile or slate roof covering might 

be replaced with a lightweight material. 

Retrofit Methods. Seismic (base) isolation (to reduce force on 

the building superstructure) is a new technique that has been 

successfully used in the retrofit of large buildings, but it is not 

appropriate to the scale and nature of school buildings unless 

the school building is considered a historical building. A newer 

technique is passive energy dissipation, the insertion of supplemental energy devices (to reduce movement), which might be 

applicable to certain types of school structures (e.g., large gymnasiums, multiuse buildings, or auditoriums). 

Seismic retrofit at any large scale is expensive, both in design 

and construction, because of the more complex analyses that 

must be conducted and the construction constraints that must 

be overcome. In addition, closure of a school for an extended 

period (beyond that of the normal summer break) is usually 

unacceptable. Major seismic retrofit is rare, although some successful projects have been done, primarily with the goal of saving 

a building that is not only a place of learning, but a historic community resource as well. The retrofitting of the B.F. Day School in 

Seattle was one such project (see Figures 4-37 and 4-38). 
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-65

Figure 4-37 

Retrofit of B.F. Day 

Elementary School, Seattle, 

WA

SOURCE: EARTHQUAKE 

ENGINEERING RESEARCH 

INSTITUTE, OAKLAND, CA; B.F. DAY 

ELEMENTARY SCHOOL , SEATTLE, 

TODD W. PERBIX AND LINDA L. 

NOSON, 1996

Figure 4-38 

Sections and plans of the B.F. Day School: existing at bottom, retrofitted at top. Note that the retrofit has 

also opened up the basement and first floor to provide large spaces suitable for today’s educational needs.

SOURCE: EARTHQUAKE ENGINEERING RESEARCH INSTITUTE, OAKLAND, CA; B.F. DAY ELEMENTARY SCHOOL , SEATTLE, TODD W. PERBIX 

AND LINDA L. NOSON, 1996

 
4-66 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

Incremental Seismic Rehabilitation. An approach that greatly improves the feasibility of retrofitting a school is that of “Incremental 

Seismic Rehabilitation.” A full description of this procedure is presented in Incremental Seismic Rehabilitation of School Buildings (K-12)

(FEMA 395). The principles of this process follow.

Whereas extensive single-stage seismic retrofitting of an existing 

school represents a significant cost, retrofit actions can be divided 

into increments and integrated into normal repairs and capital 

improvement projects. Implementation of incremental seismic 

retrofit requires assessing the buildings, establishing retrofit priorities, and planning integration with other projects. Integration 

will reduce the cost of the seismic work by sharing engineering 

design costs and some aspects of construction costs. An “integration opportunity” occurs when a seismic retrofit measure can be 

paired with other repair or replacement tasks or categories. Integration opportunities are a key consideration in determining the 

sequence of operations that will be conducted.

School districts often categorize maintenance and capital improvement projects in the following eight categories;

❍ Re-roofing

❍ Exterior wall and window replacement

❍ Fire and life safety improvements

❍ Modernization/remodeling/new technology accommodation

❍ Under floor and basement maintenance and repair

❍ Energy conservation/weatherizing/air conditioning

❍ Hazardous materials abatement

❍ Accessibility improvements
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-67

Rank*

Level of 

Seismicity

Building 

Structural 

Element

Structural 

Subsystem

Seismic 

Performance 

Improvement

Wood Masonry1 Concrete Steel

L M H

Unreinforced MasonryReinforced MasonryWood DiaphragmConcrete DiaphragmWood DiaphragmConcrete Diaphragm

Nonstructural

1    n/a n/a Bracing of 

Parapets, Gables, 

Ornamentation, and 

Appendages

    

2    n/a n/a Anchorage of 

Canopies at Exits

      

3   n/a n/a Bracing or Removal of 

Chimneys

      

10   n/a n/a Anchorage and 

Detailing of Rooftop 

Equipment

      

Structural

n/a   All 

Elements

Load Path and 

Collectors

      

n/a   Horizontal 

Elements

Diaphragms Attachment and 

Strengthening at 

Boundaries

      

n/a   Horizontal 

Elements

Diaphragms Strength/Stiffness       

n/a   Horizontal 

Elements

Diaphragms Strengthening at 

Openings

    

n/a   Horizontal 

Elements

Diaphragms Strengthening at 

Re-entrant Corners

      

Table 4-3: Roofing Maintenance and Repair/Re-roofing

Vertical Load Carrying Structure

FEMA 395 provides five matrices that show possible combinations of 

seismic improvement measures with typical work categories. A typical matrix from FEMA 395, showing possible seismic improvements 

relating to roof maintenance and repair is shown in Table 4-3.
4-68 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

*Nonstructural improvements are ranked on the basis of engineering judgment of their relative impact on improving life safety in schools.

Structural improvements are not ranked, but are organized by structural element and subsystem.

Work that may be included in the building rehabilitation/maintenance/repair project using little or no engineering.

Work requiring detailed engineering design to be included in the project.

Work requiring detailed engineering design and evaluation of sequencing requirements. The “x” designates work that could 

redistribute loads, overstressing some elements.

Note 1: Masonry buildings with a concrete roof should use the concrete building, concrete diaphragm for integration opportunities.

n/a = Not Applicable.

n/a   Horizontal 

Elements

Diaphragms Topping Slab for 

Precast Concrete

   

n/a    Vertical 

Elements

Load Path Lateral Resisting 

System to Diaphragm 

Connection

     

n/a    Vertical 

Elements

Out-of-Plane 

Anchorage of 

Concrete or Masonry 

Wall

     

Table 4-3: Roofing Maintenance and Repair/Re-roofing (continued)

Vertical Load Carrying Structure

Rank*

Level of 

Seismicity

Building 

Structural 

Element

Structural 

Subsystem

Seismic 

Performance 

Improvement

Wood Masonry1 Concrete Steel

L M H

Unreinforced MasonryReinforced MasonryWood DiaphragmConcrete DiaphragmWood DiaphragmConcrete Diaphragm







Incremental seismic retrofit is an effective, affordable, and nondisruptive strategy to achieve responsible seismic risk mitigation.

At the lower levels of protection, some effective construction measures (e.g., bracing nonstructural bookcases and filing cabinets, 

and anchoring key desktop equipment such as computers) can be 
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-69

implemented by school district maintenance personnel. As a last 

resort in cases of extreme risk and badly antiquated school buildings, demolition is the only solution. 

4.7 THE SCHOOL AS A POST-EARTHQUAKE 

SHELTER

In the aftermath of any damaging earthquake, there is an immediate need of shelter for people who have been displaced from 

their homes. There are three kinds of shelters:

❍ First is the immediate need for shelter on the day or night of 

the earthquake. The American Red Cross has a congressional 

mandate to provide this after any disaster, with the intent that 

this will be available only for a few weeks.

❍ Following the immediate need, there is a need for longerterm housing, while homes and apartments are being 

repaired. This is generally accomplished by governmental 

subsidies that enable people to move into vacant hotel rooms 

or apartments. This kind of shelter depends, to some extent, 

on the availability of these forms of housing on the market 

in the local area. This is sometimes augmented by temporary 

housing; where the season and climate allow, this can be 

provided by tents and FEMA has, in the past, maintained a 

stock of modular housing that can be moved to a local site 

within a month or two, depending on the availability of land. 

This housing may be occupied for a year or so, depending on 

the scale of the disaster. 

❍ Finally, there is permanent replacement housing that is 

typically provided by the home building industry and nonprofit housing organizations, with possible financial aid 

programs from the Federal Government. 

It is common in earthquake-prone regions for school sites to provide the first kind of immediate shelter. There are several good 

reasons for this. First, schools are conveniently located in every 

community, with easy and known access to the local population 
4-70 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

that they serve. Second, schools have suitable space (e.g., gymnasiums or multiuse rooms) where large numbers of people can be 

accommodated for a few days. Food services are often available 

and there is ample space for assembly, processing, and delivery 

of goods and equipment. Third, because schools are public 

property, the financial costs of making use of the facilities for 

a few weeks are minimal, and arrangements can be worked out 

in advance. Finally, particularly in California, where schools are 

subject to the Field Act, schools are well constructed and probably among the most likely of all the community’s buildings to 

survive intact and in a usable condition.

The only problem that has been encountered is that of ensuring 

that the time of use is limited; no school district wishes for its 

schools to be used as shelters for weeks, unless it is during the 

summer break. However, improvisation can generally ensure that 

some semblance of a normal school teaching program can be reinstated within a day or so of a moderate event. 

No specific design decisions are necessary for this use, nor is it 

necessary to stockpile emergency supplies, because they could 

use up valuable storage space for years and then be useless if 

needed. The exact circumstances of the event and the number 

and types of people to be accommodated will determine the 

supplies that are necessary. Experience has shown that local and 

even regional manufacturers and suppliers are very effective in 

providing services after an event. Following the Coalinga 1983 

earthquake, temporary shelter was provided in the high school 

gymnasium. A regional beer canning plant substituted drinking 

water for beer for a few shifts and rapidly delivered the chilled 

cans to the site.

However, pre-event planning should be undertaken between the 

school district and the local emergency services agency to anticipate key issues that will need quick solutions if an event occurs. 

This includes determining what spaces will be available and how 

many people can be accommodated, signing a pre-contract with 

a local engineer or architect for immediate post-earthquake in-
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-71

spection to determine safety, looking at strategies for continued 

operation in the event some spaces are occupied by refugees, and 

the possible provision of food and sanitary supplies by the district. 

Possible use of school buildings as a safe haven for the community in the event of chemical, biological, radiological, or 

explosive attack involves complex design and construction issues. 

This use of school property is discussed in FEMA 428, Chapter 6, 

and FEMA 453. 

4.8 REFERENCES AND SOURCES OF 

ADDITIONAL INFORMATION

ASCE, 2000, Prestandard and Commentary for the Seismic Rehabilitation 

of Buildings, American Society of Civil Engineers, FEMA Publication 

356, Washington, DC (FEMA 273 published as a standard). 

Building Construction and Safety Code NFPA 5000, National Fire 

Protection Association, Quincy, MA, 2002 .

Incremental Seismic Rehabilitation of School Buildings (K-12) (FEMA 

395), Virginia Polytechnic Institute/Building Technology 

Incorporated, Silver Spring, MD/Melvyn Green & Associates, 

Inc., Torrance, CA, Federal Emergency Management Agency, 

Washington, DC, 2002.

International Building Code 2003, International Code Council, 

Birmingham, AL, 2003.

Minimum Design Loads for Buildings and Other Structures, ASCE 7-02, 

American Society of Civil Engineers, Reston, VA, 2002.

NEHRP Commentary on the Guidelines for the Seismic Rehabilitation 

of Buildings (FEMA 274), Building Seismic Safety Council, 

Washington, DC, 1997.

NEHRP Guidelines for the Seismic Rehabilitation of Buildings (FEMA 

273), Building Seismic Safety Council, Washington, DC, 1997. 
4-72 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

NEHRP Handbook for the Seismic Evaluation of Existing Buildings

(FEMA 178), Building Seismic Safety Council, Washington, DC, 

1992.

The NEHRP Recommended Provisions for Seismic Regulation for New 

Buildings, 2000 Edition, 2 volumes and maps (FEMA 368) and 

Commentary (FEMA 369).

Primer to Design Safe School Projects in Case of Terrorist Attacks (FEMA 

428), Federal Emergency Management Agency, U.S Department 

of Homeland Security, Washington, DC, 2003.

Rapid Visual Screening of Buildings for Potential Seismic Hazards

(FEMA 154), Applied Technology Council, FEMA, Washington, 

DC, 1988.

Reducing the Risks of Nonstructural Earthquake Damage: a Practical 

Guide (FEMA 74), Wiss, Janney, Elstner Associates, Inc., 

Washington, DC, 1994.

Seismic Design Criteria of Nonstructural Systems for New School Facilities, 

EQE International/Salt Lake City School District, Salt Lake City, 

UT, 2001.

4.9 GLOSSARY OF EARTHQUAKE TERMS

Acceleration. Rate of change of velocity with time.

Amplification. A relative increase in ground motion between one 

type of soil and another or an increase in building response as a 

result of resonance. 

Amplitude. Maximum deviation from mean of the center line of 

a wave.

Architectural Components. Components such as exterior cladding, ceilings, partitions, and finishes.
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-73

Building. Any structure whose use could include shelter of 

human occupants.

Component (also Element). Part of an architectural, structural, 

electrical, or mechanical system.

Configuration. The size, shape, and geometrical proportions of 

a building.

Connection. A method by which different materials or components are joined to each other.

Damage. Any physical destruction caused by earthquakes.

Deflection. The state of being turned aside from a straight line, 

generally used in the horizontal sense; see also “Drift.”

Design Earthquake. In the IBC, the earthquake that produces 

ground motions at the site under consideration that are two/

thirds those of the “Maximum Considered Earthquake.”

Design Ground Motion. See “Design Earthquake.”

Diaphragm. A horizontal or nearly horizontal structural element 

designed to transmit lateral forces to the vertical elements of 

the seismic force resisting system.

Drift. Vertical deflection of a building or structure caused by lateral forces; see also “Story Drift.”

Ductility. Property of some materials, such as steel, to distort 

when subjected to forces while still retaining considerable 

strength.

Earthquake. A sudden motion or vibration in the earth caused 

by the abrupt release of energy in the earth’s lithosphere. 
4-74 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

Effective Peak Acceleration and Effective Peak Velocity-Related 

Acceleration. Coefficients shown on maps in the IBC for determining prescribed seismic forces.

Elastic. Capable of recovering size and shape after deformation.

Epicenter. A point on the earth’s surface that is directly above the 

focus of an earthquake.

Exceedance Probability. The probability that a specified level of 

ground motion or specified social or economic consequences 

of earthquakes will be exceeded at a site or in a region during a 

specified exposure time.

Exposure. The potential economic loss to all or certain subsets of 

the built environment as a result of one or more earthquakes in 

an area; this term usually refers to the insured value of structures 

carried by one or more insurers.

Fault. A fracture in the earth’s crust accompanied by displacement 

of one side of the fracture with respect to the other in a direction 

parallel to the fracture.

Focus. The location of a fault break where an earthquake originates; also termed “Hypocenter.” 

Force. Agency or influence that tries to deform an object or overcome its resistance to motion.

Frame, Braced. Diagonal members connecting together components of a structural frame in such a way as to resist lateral forces.

Frame, Space. A structural system composed of interconnected 

members, other than bearing walls, that is capable of supporting 

vertical loads and that also may provide resistance to seismic 

forces.
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-75

Frame System, Building. A structural system with an essentially 

complete space frame providing support for vertical loads; 

seismic forces are resisted by shear walls or braced frames. 

Frame System, Moment. A space frame in which members and 

joints are capable of resisting lateral forces by bending as well 

as along the axis of the members; varying levels of resistance 

are provided by ordinary, intermediate, and special moment 

frames as defined in the IBC with special frames providing the 

most resistance.

“g”. The acceleration due to gravity or 32 feet per second.

Ground Failure. Physical changes to the ground surface produced by an earthquake such as lateral spreading, landslides, or 

liquefaction. 

Hypocenter. See “Focus.”

Intensity. The apparent effect that an earthquake produces at a 

given location; in the United States, intensity generally is measured by the modified Mercalli intensity (MMI) scale.

Irregular. Deviation of a building configuration from a simple 

symmetrical shape.

Joint. Location of connections between structural or nonstructural members and components.

Liquefaction. The conversion of a solid into a liquid by heat, 

pressure, or violent motion; sometimes occurs to the ground in 

earthquakes.

Load, Dead. The gravity load created by the weight of all permanent structural and nonstructural building components such as 

walls, floors, roofs, and fixed service equipment.
4-76 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

Load, Live. Moving or movable external loading on a structure; it 

includes the weight of people, furnishings, equipment, and other 

items not permanently attached to the structure.

Loss. Any adverse economic or social consequences caused by 

earthquakes.

Mass. A constant quantity or aggregate of matter; the inertia or 

sluggishness that an object, when frictionlessly mounted, exhibits 

in response to any effort made to start it or stop it or to change in 

any way its state of motion.

Maximum Considered Earthquake Ground Motion. The most 

severe earthquakes effects considered in the IBC. These are represented by the mapped spectral response accelerations at short 

and long periods, obtained from maps reproduced in the IBC, 

adjusted for Site Class effects using site coefficients.

Mercalli Scale (or Index). A measure of earthquake intensity 

named after Giuseppe Mercalli, an Italian priest and geologist.

Nonbuilding Structure. A structure, other than a building, constructed of a type included in Chapter 14 of the IBC.

Occupancy Importance Factor. A factor, between 1.0 - 1.5, assigned 

to each structure according to its Seismic Use Group (SUG).

Partition. See “Wall, Nonbearing.”

Period. The elapsed time (generally in seconds) of a single cycle 

of a vibratory motion or oscillation; the inverse of frequency.

P-Wave. The primary or fastest waves traveling away from a fault 

rupture through the earth’s crust and consisting of a series of 

compressions and dilations of the ground material.
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-77

Quality Assurance Plan. A detailed written procedure that establishes the systems and components subject to special inspection 

and testing.

Recurrence Interval. See “Return Period.”

Resonance. The amplification of a vibratory motion occurring 

when the period of an impulse or periodic stimulus coincides with 

the period of the oscillating body.

Return Period. The time period in years in which the probability 

is 63 percent that an earthquake of a certain magnitude will recur.

Richter Magnitude (or Scale). A logarithmic scale expressing the 

magnitude of a seismic (earthquake) disturbance in terms of the 

maximum amplitude of the seismic waves at a standard distance 

from their focus named after its creator, the American seismologist Charles R. Richter.

Rigidity. Relative stiffness of a structure or element; in numerical 

terms, equal to the reciprocal of displacement caused by unit force.

Seismic. Of, subject to, or caused by an earthquake or an earth 

vibration.

Seismic Event. The abrupt release of energy in the earth’s lithosphere causing an earth vibration; an earthquake.

Seismic Force Resisting System. The part of the structural system 

that is designed to provide required resistance to prescribed 

seismic forces. 

Seismic Forces. The actual forces created by earthquake motion; 

assumed forces prescribed in the IBC that are used in the seismic 

design of a building and its components. 

Seismic Hazard. Any physical phenomenon such as ground 

shaking or ground failure associated with an earthquake that may 
4-78 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 

produce adverse effects on the built environment and human activities; also the probability of earthquakes of defined magnitude 

or intensity affecting a given location.

Seismic Risk. The probability that the social or economic consequences of an earthquake will equal or exceed specified values at 

a site during a specified exposure time; in general, seismic risk is 

vulnerability multiplied by the seismic hazard.

Seismic Use Group. A classification assigned in the Provisions to a 

structure based on its occupancy and use as defined in the IBC.

Seismic Waves. See “Waves, Seismic.”

Seismic Zone. Generally, areas defined on a map within which 

seismic design requirements are constant; in the IBC, seismic 

zones are defined both by contour lines and county boundaries.

Shear. A force that acts by attempting to cause the fibers or planes 

of an object to slide over one another.

Shear Panel. See “Wall, Shear.”

Shear Wall. See “Wall, Shear.”

Speed. Rate of change of distance traveled with time irrespective 

of direction.

Stiffness. Resistance to deflection or drift of a structural component or system.

Story Drift. Vertical deflection of a single story of a building 

caused by lateral forces.

Strain. Deformation of a material per unit of the original 

dimension.
MAKING SCHOOLS SAFE AGAINST EARTHQUAKES 4-79

Strength. The capability of a material or structural member to resist or withstand applied forces.

Stress. Applied load per unit area or internal resistance within a 

material that opposes a force’s attempts to deform it.

S-Wave. Shear or secondary wave produced essentially by the 

shearing or tearing motions of earthquakes at right angles to the 

direction of wave propagation.

System. An assembly of components or elements designed to perform a specific function such as a structural system.

Torque. The action of force that tends to produce torsion; the 

product of a force and lever arm as in the action of using a wrench 

to tighten a nut.

Torsion. The twisting of a structural member about its longitudinal axis. 

Velocity. Rate of change of distance traveled with time in a given 

direction; in earthquakes, it usually refers to seismic waves and is 

expressed in inches or centimeters per second.

Vulnerability. The degree of loss to a given element at risk, or set 

of such elements, resulting from an earthquake of a given intensity or magnitude; expressed in a scale ranging from no damage to 

total loss; a measure of the probability of damage to a structure or 

a number of structures.

Wall, Bearing. An interior or exterior wall providing support for 

vertical loads.

Wall, Cripple. A framed stud wall, less than 8 feet in height, extending from the top of the foundation to the underside of the 

lowest floor framing.
4-80 MAKING SCHOOLS SAFE AGAINST EARTHQUAKES

Wall, Nonbearing. An interior or exterior wall that does not 

provide support for vertical loads other than its own weight as permitted by the building code; see also “Partition.”

Wall, Shear. A wall, bearing or nonbearing, designed to resist lateral forces parallel to the plane of the wall. 

Wall System, Bearing. A structural system with bearing walls 

providing support for all or major portions of the vertical loads; 

seismic resistance may be provided by shear walls or braced 

frames.

Waves, Seismic. Vibrations in the form of waves created in the 

earth by an earthquake.

Weight. Name given to the mutual gravitational force between the 

earth and an object under consideration; varies depending on location of the object at the surface of the earth.
MAKING SCHOOLS SAFE AGAINST FLOODS 5

MAKING SCHOOLS SAFE AGAINST FLOODS 5-1

5.1 INTRODUCTION

T his chapter introduces the nature and probability of 

floods and the types of flood damage that result when 

school facilities are located in flood hazard areas. 

Avoidance of such areas is the most effective way to minimize 

risks to occupants, including health hazards and damage to property. When a school must be built in a flood 

hazard area, site layout and facility design 

measures can minimize damage and risks. The 

chapter also provides an overview of measures 

that designers should consider in order to reduce risks at existing schools that are already 

located in areas prone to flooding. 

5.2 NATURE AND 

PROBABILITY OF FLOODS

Flooding is the most common natural hazard 

in the United States, affecting over 20,000 

local jurisdictions and representing more 

than 70 percent of Presidential Disaster Declarations. Several evaluations have estimated 

that 10 percent of the Nation’s land area is 

subject to flooding. Some communities have 

very little land that is identified as exposed to 

flooding, although others lie entirely within 

the floodplain.

Flooding is a natural process that may 

manifest in a variety of forms: long-duration 

flooding along rivers that drain large watersheds; flash floods that send a devastating wall 

of water down a mountain canyon; and coastal 

flooding that accompanies high tides and 

on-shore winds, hurricanes, and Nor’easters. 

Four Examples of Schools Vulnerable to 

Flood Hazards

Two schools in Gurnee, Illinois, were 

damaged by floods in 1986. The school 

district’s actual costs were over $1.6 

million to repair and replace the facilities, 

supplies, and materials. Not included in 

these figures are the costs for transportation 

and rental, and disruption of the school 

year for children who, for several months, 

attended school in a vacant department 

store 4 miles away. For an additional 

2 years of renovation and reconstruction, 

the children attended school in another 

community, 8 miles away. One school was 

later rebuilt as a flood protected facility 

for a cost of $17 million, all of which was 

paid by local taxpayers. 

In April 2003, a dry floodproofed private 

school in Jackson, Mississippi, experienced 

a soaking when a sudden downpour 

dumped 9 inches of rain on the area. 

Because the event occurred in the pre-dawn 

hours when no one was on site to install the 

floodproofing measures (e.g., water-tight 

doors and special seals), water entered the 

building, causing damage to carpets, walls, 

furniture, and equipment.

Continued on next page
5-2 MAKING SCHOOLS SAFE AGAINST FLOODS 

In 1989, Hurricane Hugo vividly revealed 

the importance of knowing whether 

schools are prone to flooding. The local 

emergency manager’s records identified 

the McClellanville, South Carolina, 

school as an approved hurricane shelter. 

Unfortunately, that designation was based 

on erroneous information because the 

school turned out to be four feet lower than 

indicated in those records. When storm 

surge flooding inundated the school, people 

had to break through the ceiling and lift 

everyone up to the attic. 

Flooding in the spring of 2001 tested flood 

protection for the Oak Grove Lutheran High 

School in Fargo, North Dakota. Prompted 

by the failure of temporary earth and 

sandbag dikes during the 1997 Red River 

flood of record, which resulted in over $3.5 

million in damage to the school, the city 

designed and constructed a brick-faced 

permanent floodwall. Five access points, 

wide enough for vehicles, were protected 

with an “invisible” closure that is an integral 

part of the floodwall. A crew of six was able 

to install the closures in less than 2 hours.

When the natural process is unaltered by 

human activity, flooding is not a problem. In 

fact, species of plants and animals that live 

adjacent to bodies of water are adapted to a 

regimen of periodic flooding. 

Flooding is only considered a problem when 

human development is located in floodprone areas. Problems can result, not only 

exposing people to dangerous situations and 

property to damage, but also disrupting the 

natural functions of floodplains and redirecting surface flows onto lands that are not 

normally subject to flooding. 

Flooding along waterways normally occurs as 

a result of excessive rainfall or snowmelt that 

creates flood flows that exceed the capacity 

of channels. Flooding along shorelines is usually due to coastal storms that generate storm 

surges or waves above normal tidal fluctuations. Factors that can affect the frequency 

and severity of flooding and the resultant 

types of damage include:

❍ Channel obstructions due to fallen trees, 

accumulated debris, and ice jams

❍ Channel obstructions due to road and 

railroad crossings where the bridge or culvert openings are 

insufficient to convey floodwaters

❍ Erosion of shorelines and stream banks, often with episodic 

collapse of large areas of land

❍ Deposition of sediment that settles out of floodwaters or is 

carried inland by wave action

❍ Failure of dams (whether due to seismic activity, lack of 

maintenance, flows that exceed the design, or destructive acts) 

may suddenly and unexpectedly release large volumes of water
MAKING SCHOOLS SAFE AGAINST FLOODS 5-3

❍ Failure of levees (whether associated with flows that exceed 

the design, weakening by seismic activity, lack of maintenance, 

or destructive acts) may result in sudden flooding of areas 

thought to be protected

5.2.1 Characteristics of Flooding 

Each type of flooding has characteristics that are important aspects of the hazard and that must be considered in the selection 

of school sites, the design of new schools, and the expansion or 

retrofit of existing flood-prone schools in ways that minimize 

damage.

Riverine flooding is due to the accumulation of runoff from 

rainfall or snowmelt such that the volume of flow exceeds the 

capacity of waterway channels and spreads out over the adjacent 

land. Riverine flooding flows downstream under the force of 

gravity. Its depth, duration, and velocity are functions of many 

factors, including watershed size and slope, degree of upstream 

development, soil types and nature of vegetation, steepness 

of the topography, and characteristics of storms (or depth of 

snowpack and rapidity of melting). Figure 5-1 illustrates a crosssection of a riverine floodplain.

Figure 5-1 

The riverine floodplain
5-4 MAKING SCHOOLS SAFE AGAINST FLOODS 

Coastal flooding is experienced along the Atlantic, Gulf, and 

Pacific coasts, and many larger lakes, including the Great 

Lakes. Coastal flooding is influenced by storm surges associated with tropical cyclonic weather systems (hurricanes, tropical 

storms, tropical depressions, typhoons), extratropical systems 

(Nor’easters), and tsunamis (surge induced by seismic activity). 

Coastal flooding is also generally characterized by wind-driven 

waves. Wind-driven waves affect reaches along the Great Lakes 

shorelines, where winds blowing across the broad expanses of 

water generate wind-driven waves that can rival those experienced 

along other coastal shorelines. Some Great Lakes shorelines experience coastal erosion, in part associated with fluctuations in water 

levels. Figure 5-2 is a schematic of the coastal floodplain.

Figure 5-2 The coastal floodplain 
MAKING SCHOOLS SAFE AGAINST FLOODS 5-5

Riverine and coastal flooding can be characterized by a number of 

factors that become important in the selection of school sites, site 

design, and design of school buildings:

❍ Depth. The most obvious characteristic of any flood is the 

depth of water. Depending on many factors, such as the 

shape of a river valley or the presence of obstructing bridges, 

riverine flooding may rise just a few feet or tens of feet 

above normal. The depth of coastal flooding is influenced 

by such factors as the tidal cycle, the duration of the storm, 

the elevation of the land, and the presence of waves. Depth 

is a critical factor in building design because the hydrostatic 

forces that are exerted on a vertical surface (such as a 

foundation wall) are directly related to depth and because 

costs associated with protecting buildings from flooding 

significantly increase with depth.

❍ Duration. Duration is the measure of how long the water 

remains above normal levels. The duration of riverine 

flooding is primarily a function of watershed size and the 

longitudinal slope (which influences how fast water drains 

away). Small watersheds are more likely to be “flashy,” which 

refers to the rapidity with which floodwaters rise and fall. 

Areas adjacent to large rivers may be 

flooded for weeks or months. Most coastal 

flooding is influenced by the normal tidal 

cycle, as well as how fast coastal storms 

move out of the area. Areas subject to 

coastal flooding can experience long 

duration flooding where drainage is slow, 

or may be impacted on the order of 12-24 

hours if storms move rapidly. Flooding of 

large lakes, including those behind dams, 

can be of very long duration because of 

the sheer volume of water that must flow 

past a control point. For building design, 

duration is important because it affects 

access, building usability, saturation and 

Local drainage problems create ponding 

and local flooding that often is not directly 

associated with a body of water such as 

a creek or river. Although these problem 

areas generally are relatively shallow 

and often are not characterized by high 

velocity, considerable damage may result, 

especially when poor drainage causes 

repetitive damage. Some local drainage 

problems are exacerbated by old or 

undersized drainage system infrastructure. 

Because drainage problems typically occur 

as sheetflow or along waterways with very 

small drainage areas, this type of flooding 

often is not mapped or regulated.
5-6 MAKING SCHOOLS SAFE AGAINST FLOODS 

stability of soils, and building materials. Information about 

flood duration is sometimes available as part of a flood study 

or could be developed by a qualified engineer.

❍ Velocity. The rates at which floodwaters move range from 

extremely rapid (associated with flash floods) to nearly 

stagnant (in backwater areas and expansive floodplains). 

Velocity is important in site planning because of the potential 

for erosion. In structural design, velocity is a factor in 

hydrodynamic loads, including impact loads and drag forces. 

With respect to public safety, even shallow high velocity 

water poses threats to pedestrians and vehicles. Accurate 

estimates of velocities are difficult to make, although limited 

information may be found in floodplain studies.

❍ Wave action. Waves contribute to erosion and scour, and also 

contribute significantly to loads on buildings. The magnitude 

of wave forces can be 10 or more times higher than wind and 

other design loads. Waves must be accounted for along coastal 

shorelines, in flood hazard areas that are inland of open 

coasts, and other areas subject to waves, including areas with 

sufficient fetch that winds generate waves (such as lakes and 

expansive riverine floodplains).

❍ Impacts from debris and ice. Floating debris and ice 

contribute to loads that must be accounted for in design. 

The methods and models used to predict and delineate flood 

hazard areas do not specifically incorporate debris, thus there 

are few sources to characterize potential impacts other than 

past observations. 

❍ Erosion and scour. Erosion refers to a lowering of the ground 

surface in response to a flood event or the gradual recession 

of a shoreline due to long-term coastal processes. Scour 

refers to a localized lowering of the ground surface during 

a flood due to the interaction of currents and/or waves with 

structural elements, such as pilings. Erosion and scour may 

affect the stability of foundations and filled areas, and can 
MAKING SCHOOLS SAFE AGAINST FLOODS 5-7

cause extensive site damage. Soil characteristics influence 

susceptibility to scour. 

5.2.2 Probability of Occurrence

In order to guide and regulate development, and to develop specific designs to resist flood forces, it is necessary to identify the 

“design flood.” For decades, the design flood has been referred 

to as the “base flood.” More precisely, it is the “1%-annual chance 

flood,” but is commonly called the “100-year flood.” The latter 

term is often mis-understood because it conveys the impression 

that a flood of that magnitude will occur only every 100 years. 

Statistically, the 1%-annual chance flood has one chance in 100 

of occurring in any given year. The fact that a 1%-annual chance 

flood is experienced at a specific location does not alter the probability that a comparable flood will occur at the same location in 

the next year, or even twice in one year. 

Regardless of the flood selected for design purposes, the designer 

must determine specific characteristics associated with that flood. 

A flood of a specific return frequency is determined in a multistep process that typically involves using computer models that 

are in the public domain. If a sufficiently long record of floods 

exists, the design flood may be determined by applying statistical 

tools to the record. Alternatively, sometimes water resource engineers apply computer models to simulate different rainfall events 

over watersheds and to predict how much water will run off and 

accumulate in channels. Other computer models are used to 

characterize the flow of water down the watershed and predict 

how high it will rise. For coastal areas, both historical storms and 

simulated storm models can be used to predict the probability that 

floodwaters will rise to a certain level.

The National Flood Insurance Program (NFIP), described in 

Sections 5.3.1 and 5.3.2, uses the 1%-annual chance flood as 

the basis for flood hazard maps, for setting insurance rates, and 

for application of regulations in order to minimize future flood 

damage. The 1%-annual chance flood is also used to examine 
5-8 MAKING SCHOOLS SAFE AGAINST FLOODS 

older buildings to determine measures that are applied in order 

to reduce future damage.

Communities are encouraged to treat schools as essential critical 

facilities because of the significant and long-term impacts on students and the community if a damaged school is closed for an 

extended period of time. Essential and critical facilities usually are 

intended to remain operational in the event of extreme environmental loading from floods, hurricanes, snow, or seismic events. A 

higher level of protection has been determined to be appropriate 

for facilities that are important to protect in order to enhance 

rapid recovery, including hospitals, emergency operations centers, 

emergency shelters, water treatment plants, and other buildings 

that support vital services. 

5.2.3 Hazard Identification and Flood Data

Flood hazard maps are prepared to identify areas of the landscape 

that are subject to flooding, usually flooding by the 1%-annual 

chance flood. Maps prepared by the NFIP are the minimum basis 

of state and local floodplain regulatory programs. Some states 

and communities have prepared maps that reflect a floodplain 

determined using a “higher standard,” such as assuming the 

upper watershed area is built-out completely according to existing 

zoning. Some communities use a flood of record or a historically 

significant flood as the basis for regulation.

The flood hazard maps used by the appropriate regulatory authority should be consulted during site selection, site design, and 

building design (whether for new buildings or existing buildings). 

Since the NFIP began producing Flood Insurance Rate Maps 

(FIRMs), these maps have been prepared for over 19,200 communities. FIRMS are prepared for each local jurisdiction that has 

been determined to have some degree of flood risk and, typically, 

the maps may be viewed by visiting community planning or permit 

offices1. Many FIRMs do not show detailed information about 

1 Flood maps may also be viewed online at FEMA’s Map Store at http://www.fema.gov. For a fee, 

copies may be ordered online or by calling (800) 358-9616. The Flood Insurance Study (FIS) and 

engineering analyses used to determine the flood hazard area also may be ordered through the 

FEMA webpage.
MAKING SCHOOLS SAFE AGAINST FLOODS 5-9

predicted flood elevations along all bodies of water and the 0.2%-

annual chance flood hazard areas often are not shown. In these 

cases, additional engineering analyses are necessary in order to determine the flood-prone areas and the appropriate characteristics 

of flooding required for site layout and building design. 

If a proposed school site or an existing school is affected by 

flooding, a site-specific topographic survey is critical for delineating the land that is below the design flood elevation (DFE). If 

detailed flood elevation information is not available, a floodplain 

study may be required to identify the important flood characteristics and data required for sound design. Having flood hazard 

areas delineated on a map conveys a degree of precision that 

may be misleading. Flood maps have a number of limitations 

that should be examined, especially during site selection and design of essential and critical facilities such as schools:

❍ Flood hazard areas are approximations: the flood elevations 

shown and the areas delineated should not be taken as 

absolutes, in part because they are based on numerical 

approximations of the real world. 

❍ NFIP FIRMs and Flood Insurance Studies (FISs) were 

prepared to meet the requirements of the NFIP. For the most 

part, floodplains along smaller streams and drainage areas 

(less than 1 square mile) are not shown.

❍ Especially for older maps, the topography used to delineate 

the flood boundary may have had contour intervals of 5, 10, 

or even 20 feet, which significantly affects the precision with 

which the boundary is determined. The actual elevation of the 

ground relative to the flood elevation is critical, as opposed 

to whether an area is shown as being in or out of the mapped 

flood hazard area. 

❍ Older maps may not reasonably account for upland 

development that increases rainfall-runoff and tends to 

increase flooding.
5-10 MAKING SCHOOLS SAFE AGAINST FLOODS 

❍ The scale of the maps may not itself to precise determinations.

❍ Flooding may have been altered by development, whether 

upland development that increases runoff or local 

modifications that alter the shape of the land surface of the 

floodplain (such as fills or levees).

❍ Local conditions are not reflected, especially conditions that 

change regularly, such as streambank erosion and shoreline 

erosion.

The flood hazard maps prepared by the NFIP show different 

zones that identify some differences in flooding characteristics:

❍ A Zones. Flood hazard areas where engineering analyses have 

not been performed to develop detailed flood elevations 

and boundaries, also called “unnumbered A Zones” or 

“approximate A Zones,” for the base flood (1%-annual 

chance flood). Additional engineering analysis and sitespecific assessments usually are required to determine the 

design flood elevation.

❍ AE Zones or A1-A30 Zones. These designations are used 

for flood hazard areas where engineering analyses have 

produced detailed flood elevations and boundaries for the 

base flood (1%-annual chance flood). For riverine waterways 

with these zones, FISs include longitudinal profiles showing 

water surface elevations for different frequency flood events.

❍ Floodways. The floodway includes the waterway channel 

and adjacent land areas that must be reserved in order to 

convey the discharge of the base flood without cumulatively 

increasing the water surface elevation more than a 

designated height. Floodways are designated for most 

waterways that have AE Zones. FISs include data on floodway 

widths and mean floodway velocities. 
MAKING SCHOOLS SAFE AGAINST FLOODS 5-11

❍ AO and AH Zones. Areas of shallow flooding are generally 

shown where the flood depth averages from 1 to 3 feet, where 

a clearly defined channel does not exist, where the path of 

flooding is unpredictable, and where velocity flow may be evident. These zones are characterized by ponding or sheetflow. 

❍ Shaded X (or B) Zones. This zone shows areas of the 500-year 

flood (0.2%-annual chance flood), or areas protected by flood 

control levees. This zone is not shown on many NFIP maps 

and its absence does not imply that flooding of this frequency 

will not occur. 

❍ Unshaded X (or C) Zones. These zones are all land areas not 

mapped as flood hazard areas (either 1%- or 0.2%-annual 

chance flood hazard areas) that are outside of the floodplain 

that is designated for the purposes of regulating development 

pursuant to the NFIP. These zones may still be subject to small 

stream flooding and local drainage problems.

❍ V Zones (V, VE, and V1-V30). Also known as “coastal high 

hazard areas,” V Zones are relatively narrow areas along open 

coastlines and some large lake shores that are subject to highvelocity wave action from storms or seismic sources. V Zones 

extend from off-shore to the inland limit of a primary frontal 

dune or to an inland limit where breaking waves are predicted 

to be at least 3 feet in height.2

❍ Coastal A Zone. The principal sources of flooding in Coastal 

A Zones are astronomical tides, storm surges, seiches, 

or tsunamis. These zones extend inland to include areas 

where the potential for breaking wave heights exists during 

conditions of the base flood. Coastal A Zones are not 

delineated on NFIP maps; this zone is identified in ASCE 7 

and ASCE 24 because waves sufficient to contribute to damage 

are present. 

2 Because V Zones are generally limited in extent, such areas are unlikely sites for schools. 

The specific design and construction provisions for V Zones are not addressed in this manual. 

More information can be found in FEMA 55, Coastal Construction Manual. 
5-12 MAKING SCHOOLS SAFE AGAINST FLOODS 

Figure 5-3 Riverine flood hazard zones

Flood hazards and characteristics of flooding must be identified 

in order to appropriately evaluate the impact of site development, 

to calculate flood loads, to design floodproofing measures, or 

to identify and prioritize retrofit measures for existing schools. 

Many characteristics are not shown on the flood hazard maps but 

may be found in the FIS or the study or report prepared by the 

entity that produced the flood hazard map. Otherwise, additional 

research is required. Table 5-1, on page 5-22, outlines a series of 

questions to facilitate this objective.
MAKING SCHOOLS SAFE AGAINST FLOODS 5-13

5.2.4 Design Flood Elevation 

The design flood elevation establishes the 

minimum level of flood protection that 

must be provided. DFE as used in the model 

building codes is defined as either the base 

flood elevation (BFE) determined by the 

NFIP or the elevation of a design flood designated by the community, whichever is higher. 

The DFE will always be at least as high as the BFE. Communities 

may use a design flood that is higher than the base flood for a 

number of reasons, (e.g., to account for future upland development, recognize a historic flood, or incorporate a factor of safety, 

known as freeboard). 

Figure 5-4 shows the relationship between the BFE and the DFE. 

School planners and designers should check with the appropriate 

regulatory authority to determine the minimum flood elevation 

to be used in site planning and design. For essential and critical 

facilities such as schools, it is common that state and local regulations cite the 0.2% chance flood (500-year flood) as the design 

minimum or the regulations may call for added freeboard of 1, 2, 

or 3 feet above the minimum flood elevation. 

Figure 5-4 Definition sketch – flood elevations

The DFE is the highest elevation of either the 

flood hazard area shown on a community’s 

Flood Insurance Rate Map, or another flood 

as legally designated by a community (e.g., 

accounting for future development).
5-14 MAKING SCHOOLS SAFE AGAINST FLOODS 

5.3 SCOPE, EFFECTIVENESS, AND 

LIMITATIONS OF BUILDING CODES 

AND FLOODPLAIN MANAGEMENT 

REQUIREMENTS 

With respect to design and construction to resist flood damage, 

the existing minimum requirements in model building codes and 

regulations are based on the National Flood Insurance Program. 

The original authorizing legislation for the NFIP was passed in 

1968. Congress expressly found that “a program of flood insurance can promote the public interest by encouraging sound land 

use by minimizing exposure of property to flood losses . . . ”

The most convincing evidence of the effectiveness of the NFIP 

minimum requirements is found in flood insurance claim payment statistics. Buildings that pre-date the NFIP requirements are, 

by and large, not constructed to resist flood damage. Buildings 

that post-date the NFIP (i.e., those that were constructed after a 

community joined and began applying the 

minimum requirements) are designed to 

resist flood damage. The NFIP reports that aggregate loss data indicate that buildings that 

meet the minimum requirements experience 

70 percent less damage than do buildings that 

pre-date the NFIP. There is ample evidence 

that buildings that exceed the minimum 

requirements are even less likely to sustain 

damage. 

5.3.1 Overview of the NFIP

The NFIP is intended to encourage states and local governments 

to recognize and incorporate flood hazards in land use and development decisions. In some states and communities, this is 

achieved by guiding development to areas with lower risk. When 

decisions result in development within flood hazard areas, application of the criteria set forth in Federal Regulation at 44 CFR §60.3 

minimize exposure and flood-related damage. State and local govConstruction of public schools may be 

regulated by a state board or agency and 

thus may not be subject to local permit 

requirements, including local floodplain 

management regulations. In these cases, 

the NFIP minimum requirements must still 

be satisfied, whether through regulation, 

executive order, or a state building code. 
MAKING SCHOOLS SAFE AGAINST FLOODS 5-15

ernments are responsible for the application of the provisions of 

the NFIP through regulatory permitting processes. At the federal 

level, the NFIP is managed by FEMA and has three main elements:

❍ Hazard identification and mapping, under which engineering 

studies are conducted and flood maps are prepared in 

partnership with states and communities to delineate areas 

that are predicted to be subject to flooding under certain 

conditions. 

❍ Floodplain management criteria for development, which 

establish the minimum requirements to be applied to 

development within mapped flood hazard areas with the intent 

of recognizing hazards in the entire land development process. 

❍ Flood insurance, which provides financial protection for 

property owners to cover flood-related damage to buildings 

and contents.

Federal flood insurance is designed to provide property owners, 

including school districts, an alternative to disaster assistance 

and disaster loans. Disaster assistance has limited coverage for 

full costs to repair and clean up and is available only after the 

President of the United States signs a disaster declaration for 

the area. Importantly, school districts should be aware that they 

may be subject to a mandated reduction in disaster assistance 

payments if a public school building is not covered by flood insurance. NFIP flood insurance claims are paid any time damage 

from a qualifying flood event occurs, regardless of whether a 

major disaster is declared.

Another important objective of the NFIP is to break the cycle 

of flood damage. Many buildings have been flooded, repaired 

or rebuilt, and flooded again. Before the NFIP, in some parts 

of the country, this cycle occurred every couple of years, with 

reconstruction taking place in the same flood-prone areas using 

the same construction techniques that did not adequately resist 

flood damage. By guiding development to lower risk areas and 
5-16 MAKING SCHOOLS SAFE AGAINST FLOODS 

by requiring compliance with performance measures to minimize exposure of new buildings and buildings that undergo 

major renovation or expansion, the long-term objective of disaster resistant communities can be achieved. 

5.3.2 Summary of the NFIP Minimum 

Requirements 

The performance requirements of the NFIP are set forth in 

federal regulation at 44 CFR Part 60. The requirements apply 

to all development, which the NFIP broadly defines include 

buildings and structures, site work, roads and bridges, fills and 

other activities. Buildings must be designed 

and constructed to resist flood damage, 

which is primarily achieved through elevation (or floodproofing). Additional specific 

requirements apply to existing development, especially existing buildings. Existing 

buildings that are proposed for substantial 

improvement, including repair of substantial 

damage, are subject to the regulations. 

Although the NFIP regulations primarily focus on how to build, 

one of the long-term objectives of the program is to guide development to less hazardous locations. Preparing flood hazard maps 

and making the information available to the public is fundamental 

in satisfying that objective. With that information, people can 

make informed decisions about where to build, how to use site 

design to minimize exposure to flooding, and to how to design 

buildings that will resist flood damage.

The NFIP’s broad performance requirements for site work are as 

follows:

❍ Building sites shall be reasonably safe from flooding.

❍ Adequate site drainage shall be provided to reduce exposure 

to flooding. 

“Substantial improvement” is any repair, 

reconstruction, rehabilitation, addition 

or improvement of a building, the cost of 

which equals or exceeds 50 percent of 

the market value of the building before the 

improvement or repair is started (certain 

historic structures may be excluded).
MAKING SCHOOLS SAFE AGAINST FLOODS 5-17

❍ New and replacement sanitary sewage systems shall be designed 

to minimize or eliminate infiltration of floodwaters into the 

systems and discharges from the systems into floodwaters.

❍ Development in floodways shall be prohibited unless 

engineering analyses show that there will be no increases in 

flood levels. 

The NFIP’s broad performance requirements for new buildings 

proposed for flood hazard areas (and substantial improvement of 

existing flood-prone buildings) are as follows:

❍ Buildings shall be designed and adequately anchored to 

prevent flotation, collapse, or lateral movement resulting 

from hydrodynamic and hydrostatic loads, including the 

effects of buoyancy.

❍ Buildings shall be constructed by methods and practices that 

minimize flood damage (primarily by elevating to or above 

the base flood level or by specially designed and certified 

floodproofing measures).

❍ Buildings shall be constructed with electrical, heating, 

ventilation, plumbing, and air conditioning equipment and 

other service facilities that are designed and/or located so as 

to prevent water from entering or accumulating within the 

components.

Designers should determine if there are any applicable state-specific requirements pertinent to floodplain development. Some 

states require that local jurisdictions apply standards that exceed 

the minimum requirements of the NFIP. Some states have direct 

permitting authority programs that impose higher standards, 

while some states have direct permitting authority over certain 

types of construction or certain types of applicants. 

As participants in the NFIP, states are required to ensure that 

development that is not subject to local regulations, such as state 
5-18 MAKING SCHOOLS SAFE AGAINST FLOODS 

construction, satisfies the same performance requirements. If 

schools are exempt from local permits, this may be accomplished 

through a state permit, a governor’s executive order, or other 

mechanism that applies to entities not subject to local authorities.

5.3.3 Model Building Codes and Standards 

The 2000 and 2003 editions of the International Building Code 

(IBC) and the 2003 edition of the National Fire Protection Association’s Building Construction and Safety Code (NFPA 5000) are 

the first model codes to include comprehensive provisions to address flood hazards. Both codes are consistent with the minimum 

provisions of the NFIP that pertain to design and construction of 

buildings. The NFIP requirements that pertain to site development and floodways generally are found in other local ordinances. 

The codes require designers to identify anticipated environmental 

loads and load combinations, including wind loads, seismic loads, 

snow loads, soil conditions and flood loads. 

The IBC and NFPA 5000 reference standards that are developed 

through a rigorous consensus process. The best known is Minimum 

Design Loads for Buildings and Other Structures (ASCE 7), produced 

by the American Society of Civil Engineers (ASCE). The model 

building codes require that applicable loads be accounted for in 

the design. The designer must identify the pertinent, site-specific 

characteristics and then use ASCE 7 to determine the specific 

loads and combined loads. In effect, it is similar to a local floodplain ordinance that requires determination of the environmental 

condition (in/out of the mapped flood hazard area, DFE/depth 

of water) and then specifies certain conditions that must be met 

during design and construction. The 1998 edition of ASCE 7 was 

the first version of the standard to explicitly include flood loads, 

including hydrostatic loads, hydrodynamic loads (velocity and 

waves), and debris impact loads. 

The IBC and NFPA 5000 also refer to a standard first published by 

ASCE in 1998, Flood Resistant Design and Construction (ASCE 24). 

Developed through a consensus process, ASCE 24 addresses spe-
MAKING SCHOOLS SAFE AGAINST FLOODS 5-19

cific topics pertinent to designing buildings in flood hazard areas, 

including floodways, coastal high hazard areas, and other high-risk 

flood hazard areas such as alluvial fans, flash flood areas, mudslide 

areas, erosion-prone areas, and high velocity areas. 

5.4 RISK REDUCTION: AVOIDING FLOOD 

HAZARDS 

Flood hazards are unlike earthquake hazards and wind hazards. 

Those hazards often are assigned at the county level because the 

hazards themselves do not significantly vary from one geographic 

location within a county to another. Of course, there may be 

site-specific variations in those hazards, such as soils susceptible 

to liquifaction during seismic activity, or local topographic differences that influence wind speeds. However, for the most part, 

the earthquake and wind hazards cannot be avoided by choosing 

alternative locations. 

Flood hazards are site-specific. When a flood hazard map is 

prepared, lines drawn on the map appear to precisely define 

the hazard area. Land that is on one side of the line is “in” the 

mapped flood hazard area, while the other side of the line is 

“out.” Although the delineation may be an approximation, 

having hazard areas shown on a map facilitates avoiding such 

areas to the maximum extent practical. Where it is unavoidable, 

school districts should carefully evaluate all of the benefits and 

all of the costs in order to determine long-term acceptable risks 

and to develop appropriate plans for design and construction of 

new schools.

Section 5.6 describes the damage that is sustained by existing 

buildings that are exposed to flood hazards, including: site 

damage; structural and nonstructural building damage; destruction or impairment of service equipment; loss of contents; and 

health and safety threats due to contaminated floodwaters. 

These types of damage, along with loss of function and community service, are avoided if schools are located away from flood 

hazard areas. Damage is minimized when schools that must be 
5-20 MAKING SCHOOLS SAFE AGAINST FLOODS 

located in flood hazard areas are built in compliance with minimum requirements.

5.4.1 Benefits/Costs: Determining Acceptable 

Risk

Many decisions that are made with respect to schools are, in part, 

based on a determination of acceptable risk. Risk includes the 

potential losses associated with a hazard. Ideally, risk is defined in 

terms of expected probability and frequency of the hazard occurring, people and property exposed, and potential consequences. 

Choosing a site or accepting donated land that is affected by 

flooding is a decision to accept some degree of risk. Although the 

flood-prone land may have a lower initial cost, the incremental 

costs of construction plus the likely increased costs of maintenance, repair, and replacement may be significant. Another cost 

of locating a school in a flood-prone area is access. Although the 

building may be elevated and protected, if access is restricted periodically, the use of the school also is affected. 

The school district’s planning team and the design team can influence the degree of risk (e.g., the frequency with which flooding 

may affect the site). They control it through selection of site design and building design measures. Fundamentally, this process is 

a balancing of the benefits of an acceptable level of disaster resistance with the costs of achieving that degree of protection. With 

respect to mitigation of future hazard events:

❍ Benefits are characterized and measured as damage avoided 

if the mitigation measures (including avoiding flood hazard 

areas) are implemented.

❍ Costs are the costs associated with implementing measures to 

eliminate or reduce exposure to hazards. 
MAKING SCHOOLS SAFE AGAINST FLOODS 5-21

Section 5.6 describes damage and losses that are incurred by 

buildings exposed to flooding. Direct damage includes damage to 

physical property, including the site, the building, building materials, utilities, and building contents. Indirect damage that is not 

listed includes health hazards, functionality impacts, emergency 

response, evacuation, and expenses associated with occupying another building during repairs.

For the most part, benefits are difficult to measure because they 

are associated with damage that does not occur, cleanup that is 

not required, and service that is uninterrupted because flooding 

does not shut down a school. In addition, benefits accrue over 

long periods of time, thus making it more difficult to make a direct comparison of benefits with costs of mitigation. Mitigation 

costs can more readily be expressed in terms of the higher costs of 

a flood-free site or the initial capital costs of work designed to resist flood damage. Thus, without a full accounting of both benefits 

and costs, decision makers may not be able to make fully informed 

decisions. Some questions that should be answered include:

❍ If the site is flood-prone and the building is out of the flood 

hazard area or elevated on fill, what are the average annual 

cleanup costs associated with removal of sand, mud, and 

debris deposited by floods of varying frequencies?

❍ If the school building is elevated by means other than fill, 

will periodic inundation of the exposed foundation elements 

cause higher average annual maintenance costs?

❍ If the school building meets only the minimum elevation 

requirements, what are the average annual damage and 

cleanup costs over the anticipated useful life of the building, 

including the occurrence of floods that exceed the design 

flood elevation?

❍ How do long-term costs associated with periodic inundation 

compare to up-front costs of selecting a different site or 

building to a higher level of protection?
5-22 MAKING SCHOOLS SAFE AGAINST FLOODS 

❍ If access to the school is periodically restricted due to 

flooding, especially long-duration flooding, what cost impacts 

will result? How often would the school district have to 

provide an alternate location to continue classes? 

5.4.2 Identifying Flood Hazards at School Sites

To the extent practical, schools and attendant athletic fields and 

facilities should be located outside of known flood hazard areas. 

The best available information regarding flooding should be 

examined, including flood hazard maps, records of historical 

flooding, and advice from local experts, and others who can evaluate flood risks. 

As part of site selection and to guide locating the school building 

and other improvements on a site, designers should investigate 

site-specific flood hazard characteristics. Table 5-1 outlines questions that will produce information that must be determined prior 

to initiating site layout and design work.

Evaluation Question

Evaluation 

Y or N or 

Comment

Guidance Data Reference

Is the site near a body 

of water (with or without 

a mapped flood hazard 

area)? 

All bodies of water are subject to flooding, 

but not all have been designated as 

floodplain on FIRMs. This provides 

information about the flood hazard on 

the site and, if present, determines certain 

regulatory requirements. 

FIRM or local flood hazard maps; available 

for review in local planning and permit 

offices. Site-specific analyses should be 

performed by qualified water resources 

engineers. 

Is the site affected by a 

regulatory floodway? 

Development in floodways, including fill 

and construction of buildings, is prohibited 

unless demonstrated that there will be no 

resulting increase in flood elevations.

FIRM, Flood Hazard Floodway Boundary 

Map, local flood hazard maps; available for 

review in local planning and permit offices.

Table 5-1: Flood Hazards at School Sites 
MAKING SCHOOLS SAFE AGAINST FLOODS 5-23

Has the site been 

affected by past flood 

events?

Records of actual flooding augment 

studies that predict flooding, especially 

if historic events resulted in deeper or 

more widespread flooding.

Local planning and permit offices; local 

historical society; State Department of 

Transportation; State Water Resources or 

Emergency Management Agency; Natural 

Resources Conservation Service; U.S. 

Army Corps of Engineers.

Can the site 

be accessed by 

emergency and fire 

vehicles during flood 

events?

Firefighting efforts during floods are 

compounded when access roads are 

flood-prone.

Topographic map with delineated flood 

hazard area and flood depths used for 

site layout and access road design.

What is the required 

minimum protection 

level required 

by regulatory 

authorities? 

The 100-year and 500-year flood levels 

are the minimum required protection 

levels for projects in mapped flood 

hazard areas. Critical facilities (including 

schools) may be required to be above 

the 500-year flood level. Lower levels 

of protection may be allowed outside 

the regulated areas, but are not 

recommended. 

Authority having jurisdiction that 

establishes design criteria for schools; 

state building codes and floodplain 

regulations; local building codes and 

floodplain regulations.

What is the DFE? Land below the DFE is in the 

“floodplain” and subject to regulatory 

provisions. The DFE is the basis for 

minimum protection measures; critical 

facilities (including schools) should be 

protected to at least 2- or 3-feet higher.

FIRM; local flood hazard map; flood 

profiles along waterways with detailed 

studies; site-specific studies for flood 

hazard areas identified without flood 

elevations.

What is the predicted 

depth of flooding?

The depth of flooding influences site 

layout, site modifications, design of 

protection measures, and computation 

of loads on buildings. Sites with deep 

flooding are less feasible to develop 

efficiently and cost effectively.

The DFE minus the ground elevation at 

specific site yields the predicted depth 

of water. For large parcels of land, the 

depth of flooding is likely to vary over 

the site.

Table 5-1: Flood Hazards at School Sites (continued)

Evaluation Question

Evaluation 

Y or N or 

Comment

Guidance Data Reference
5-24 MAKING SCHOOLS SAFE AGAINST FLOODS 

What is the expected 

velocity of floodwaters 

on the school site? 

Velocity is the rate at which water moves 

and is measured in feet per second. Velocity 

is a factor in computing loads associated 

with hydrodynamic forces, including drag 

on building surfaces. Depending in part on 

soil types and vegetative cover, velocity is 

related to erosion, including streambank 

erosion, erosion of earthen fill, and local 

scour around buildings. Velocity also affects 

public safety.

Approximations of velocity may be 

interpolated from data in the Floodway 

Data Table if the waterway was studied 

using detailed methods, application 

of approximation methods based on 

continuity, local observations and sources, 

or site-specific studies. 

Are waves expected to 

affect the floodplain on 

the site?

(Note: Coastal high 

hazard areas (V Zones) 

are not addressed in this 

manual.)

Waves can exert considerable dynamic 

forces on buildings and contribute to 

erosion and scour. Wind-driven waves occur 

in areas subject to coastal flooding (see 

discussion on Coastal A Zones) and where 

unobstructed winds affect wide floodplains 

(large lakes and major rivers). Standing 

waves may occur in riverine floodplains 

where high velocities are present. 

FIS (coastal areas); local observations of 

past events; interpolation of results of sitespecific engineering analyses (hydraulic 

modeling). 

Are heavy debris loads 

and sediment deposits 

expected (e.g, on 

alluvial fans)? 

Removal of debris and sediment deposits 

can be expensive, especially from finely 

graded athletic fields. Impact loads 

associated with floating debris must be 

accounted for in design.

Local observations of past events; 

examination of local land forms created by 

flood-borne sediments.

How long will water 

remain on the school 

site? 

Duration of flooding affects the stability 

of permeable and porous building 

materials. Unless specifically designed 

for total saturation, earthen fills may 

become unstable under long-duration flood 

conditions. Duration may affect site access 

and emergency response. 

Local observations of past events; 

examination of site-specific engineering 

analyses (hydrologic modeling). 

How quickly will 

floodwaters affect the 

site?

Warning time is a key factor in the safe 

and orderly evacuation of a school. Certain 

protective measures require adequate 

warning time so that specific actions can be 

taken by skilled personnel. 

Local emergency manager; local 

observations; National Weather Service.

Table 5- 1: Flood Hazards at School Sites (continued)

Evaluation Question

Evaluation 

Y or N or 

Comment

Guidance Data Reference
MAKING SCHOOLS SAFE AGAINST FLOODS 5-25

If the waterway is on or 

adjacent to the school 

site, is there evidence of 

bank erosion?

Erosion is a natural riverine process. Land 

adjacent to actively eroding waterways is 

considered unstable over the long term. 

Improvements should not be exposed to 

active erosion, or the site design must 

include stabilization measures. 

Site inspection; local observations of past 

events; soils testing.

Is the site within the 

area predicted to flood if 

a levee or floodwall fails 

or is overtopped?

Flood protection works may be distant 

from sites and not readily observable. 

Although a low probability event, failure 

or overtopping can cause unexpected and 

catastrophic damage because the protected 

lands are not regulated as flood hazard 

areas.

Local public works department; state 

floodplain management agency; U.S. Army 

Corps of Engineers. 

Is the site within the 

area predicted to flood if 

an upstream dam fails?

The effects of an upstream dam failure 

are not shown on the FIRM or most flood 

hazard maps prepared locally. Although 

dam failure is considered a very unlikely 

event, the potential threat should 

be evaluated due to the catastrophic 

consequences. (Note: Owners of certain 

dams should have Emergency Action 

Plans geared towards notification and 

evacuation of vulnerable populations.)

Local emergency management office; state 

dam safety office.

Is there a formal channel 

maintenance program? 

Flooding can be exacerbated by debris 

blockages or build-up of excessive 

sediment in the channel. 

Local public works or road maintenance 

department.

Are there nearby 

locations on the 

waterway where debris 

may affect the flow of 

water (e.g., bridges, 

culverts, narrow 

valleys)?

Flooding may be exacerbated by debris 

blockages where flow is constricted. 

Local public works or road maintenance 

department.

Table 5- 1: Flood Hazards at School Sites (continued)

Evaluation Question

Evaluation 

Y or N or 

Comment

Guidance Data Reference
5-26 MAKING SCHOOLS SAFE AGAINST FLOODS 

5.5 RISK REDUCTION: FLOOD-RESISTANT 

NEW SCHOOLS

When a decision is made to build a new school on a site that 

is affected by flooding, the characteristics of the site and the 

nature of flooding must be examined prior to making several 

design decisions. The most important consideration is location 

of the buildings.

Risks and certain costs associated with flood-resistant construction are minimized by putting principal buildings on the highest 

available ground. Positioning the buildings, parking lots, and 

athletic fields is influenced by identification of all site constraints, 

which include such factors as presence of flood hazard areas (see 

Table 5-1), wetlands, poor soils, steep slopes, sensitive habitats, 

mature tree stands, and other environmental factors required by 

the authority that approves development plans and all applicable 

regulatory authorities.

Several aspects of design of flood-resistant buildings and sites 

are important and are described in this section, including site 

modifications, foundation type and elevation considerations, floodproofing options, flood-resistant accessory structures, building 

service equipment and utility installations, and access roads.

5.5.1 Site Modifications

When sites that are affected by flood hazard areas must be used, 

and when flood hazard areas cannot be avoided, it may be appropriate to evaluate certain site modifications that may be feasible to 

provide a level of protection to buildings. The evaluations involve 

engineering analyses in order to determine if the desired level of 

protection can be provided cost-effectively, while ensuring that 

site modifications do not alter the floodplain in ways that increase 

flooding. Typical site modifications (with cautions that must be examined to determine effectiveness) include:

❍ Earthen fill. Fill can be placed in the flood hazard area with 

the effect of moving the floodplain boundary. If the fill is 
MAKING SCHOOLS SAFE AGAINST FLOODS 5-27

placed and compacted to be stable during the rise and fall 

of floodwaters and is protected from erosion, modifying a 

site with fill in order to elevate a school is preferred over 

other methods of elevation. Not only will the building be 

less exposed to flood forces, but, under some circumstances 

(long duration floods), the school may be able to continue 

to function. Whether nonstructural fill is placed solely to 

modify the site, or structural fill is placed for the purpose of 

elevating buildings, placement of fill can change flooding 

characteristics. Engineering analyses can be conducted to 

determine if eliminating floodplain storage by fill will result in 

changing the flow of water, creating higher flow velocities, or 

increasing the water surface elevation. 

❍ Excavation. Excavation alone rarely results in significantly 

altering the floodplain on a given parcel of land. It is more 

commonly used in conjunction with fill in order to off-set or 

compensate for the adverse impacts of fill.

❍ Earthen levee or dike. A levee is a specially designed barrier 

that modifies the floodplain by keeping the water away. Levees 

are significant structures that require detailed, site-specific 

geotechnical investigations; engineering analyses to identify 

whether flooding will be made worse on other properties; 

structural and site design to suit existing constraints; design 

of interior drainage (on the land side); and long-term 

commitment for maintenance, inspection, and repairs. It 

is important to remember that areas protected by levees 

are protected only up to a certain design flood level; once 

overtopped, most levees fail and catastrophic flooding of 

previously protected areas results. Levees that protect essential 

and critical facilities usually are designed for the 0.2%-annual 

chance flood (500-year) and have added height (called 

“freeboard”) to increase the factor of safety (see Figure 5-4).

❍ Floodwall. Floodwalls are similar to levees in that they provide 

protection only up to a certain design flood level, and 

overtopping can result in catastrophic flooding. A floodwall 
5-28 MAKING SCHOOLS SAFE AGAINST FLOODS 

typically is a significant structure that is designed specifically 

to hold back water of a certain depth based on the design 

flood for the site. Generally, due to design factors, floodwalls 

are most effective in areas with relatively shallow flooding. As 

with levees, designs must accommodate interior drainage on 

the land side, and maintenance and operations are critical 

for adequate performance. Floodwalls that protect essential 

and critical facilities usually are designed for the 0.2%-annual 

chance flood (500-year) and have added height (freeboard) 

to increase the factor of safety. 

5.5.2 Elevation Considerations

The selection of the appropriate method of elevating school buildings above the design flood elevation depends on many factors, 

including cost, level of safety and property 

protection desired, nature of the flood hazard 

area, etc. The minimum requirement is that 

the lowest floor (including basement) be at or 

above the DFE (plus freeboard, if required); 

given the importance of school buildings, 

additional height above that elevation is appropriate. Elevation can be accomplished by 

different foundation methods: 

❍ Slab-on-grade on structural fill. This is considered to be the 

safest method to elevate a building. Structural fill can be 

placed and shaped so that, when water rises up to the DFE, 

it will not touch the building (Figure 5-5) and building 

access is maintained. The fill must be designed to minimize 

adverse impacts such as increasing flood elevations on 

adjacent properties, increasing erosive velocities, and causing 

local drainage problems. To ensure stability, especially as 

floodwaters recede and the soils drain, fill must be designed 

for the anticipated water depths and duration. A geotechnical 

engineer or soil scientist may need to examine underlying soils 

to determine if consolidation over time may occur. In addition, 

the effects of long-term compaction of the fill should be 

“Lowest floor” means the lowest floor of the 

lowest enclosed area (including basement). 

An unfinished or flood-resistant enclosure, 

usable solely for parking of vehicles, 

building access, or storage in an area 

other than a basement, is not the lowest 

floor provided the enclosure is built in 

compliance with applicable requirements.
MAKING SCHOOLS SAFE AGAINST FLOODS 5-29

considered, and may prompt additional elevation as a factor of 

safety. The horizontal extent of fill from the foundation should 

be designed to facilitate access by emergency and fire vehicles, 

with a minimum 25-foot width recommended. Designers are 

cautioned to avoid excavating a basement into fill without 

added structural protection due to the potential for significant 

hydrostatic loads and uplift on basement floors.

Figure 5-5 High school in Bloomsburg, PA, elevated on fill

 SOURCE: U.S. ARMY CORPS OF ENGINEERS, FLOOD-PROOFING SYSTEMS & TECHNIQUES, 1984

❍ Stem walls (earth-filled perimeter walls). Stem wall 

foundations are designed to come in contact with floodwaters 

on the exterior. They are more stable than perimeter walls 

(crawlspaces), but could experience structural damage if 

undermined by local scour and erosion. Designs must account 

for anticipated debris and ice impacts and incorporate 

methods and materials to minimize impact damage.

❍ Columns or shear walls. Open foundations minimize changes 

to the floodplain and local drainage patterns, and the area 

under the building can be used for student activities or 

parking (see Figure 5-6). Columns and shear walls must also 

account for hydrodynamic loads and debris and ice impact 

loads. Flood loads on shear walls are reduced if they are 
5-30 MAKING SCHOOLS SAFE AGAINST FLOODS 

oriented parallel to the anticipated direction of flow. Erodible 

soils may be present and local scour may occur; both must be 

accounted for in designs by extending the foundation wall 

below the expected scour depth.

Figure 5-6 Elementary school in Jefferson County, OH, elevated on columns

 SOURCE: U.S. ARMY CORPS OF ENGINEERS, FLOOD-PROOFING SYSTEMS & TECHNIQUES, 1984

❍ Extended solid perimeter walls (crawlspace). Unlike stem 

wall foundations, solid perimeter walls enclose an open area 

and must be designed with openings specifically intended 

to equalize interior and exterior water levels to prevent 

differential hydrostatic pressures that could lead to structural 

damage. Wall design must also account for hydrodynamic 

loads, and debris and ice impact loads. The enclosed area (the 

crawlspace) must not contain equipment (including ductwork) 

below the DFE (plus freeboard, if required). Designers must 

provide adequate underfloor ventilation and subsurface 

drainage to minimize moisture problems after flooding.

❍ Pier supports for portable classroom units. Manufactured 

buildings must be elevated above the DFE (plus freeboard, if 

required). Pier supports must also account for hydrodynamic 
MAKING SCHOOLS SAFE AGAINST FLOODS 5-31

loads, and debris and ice impact loads, and units must be 

anchored to resist wind loads. Although written specifically for 

manufactured housing units, FEMA 85, Manufactured Home 

Installation in Flood Hazard Areas, has useful information that is 

applicable to portable classrooms. 

5.5.3 Floodproofing Considerations 

According to the model building codes and the NFIP regulations, schools are treated as nonresidential buildings and may 

be dry floodproofed using measures to prevent water from penetrating the building envelope and utilities. However, careful 

consideration of the implications of potential physical damage 

and safety should be undertaken before a decision is made to 

construct new schools using floodproofing methods. 

All flood protection measures are designed for certain flood conditions. Therefore, there is always a chance that the design will 

be exceeded (i.e., water will rise higher than accounted for in 

the design). When this happens to a dry floodproofed building, 

the consequences can be catastrophic. As a general rule, floodproofing is a poor choice for new essential and critical facilities 

(including schools) when avoidance of the floodplain or elevation methods to raise the building above the flood level can be 

applied. Floodproofing may be acceptable for retrofitting existing schools under certain circumstances (see Section 5.7.4).

Dry floodproofing involves a combination of 

design and special features that are intended 

to prevent the entry of water into a building 

while also resisting flood forces. It involves 

structural reinforcement so that exterior walls 

are sufficiently robust to withstand the loads 

described in Section 5.2.1 (hydrostatic pressure, hydrodynamic loads, wave loads, and debris impact loads). 

For NFIP flood insurance, floodproofing must extend at least 1 

foot above the BFE or premiums will be very costly. Therefore, 

a higher level of protection is recommended. Exterior walls 

Floodproofed schools must never be considered safe for occupancy during periods 

of high water; floodproofing measures are 

intended only to reduce physical damage.
5-32 MAKING SCHOOLS SAFE AGAINST FLOODS 

must also be designed to prevent infiltration and seepage of water, 

whether through the wall itself or through any openings, including 

where utility lines penetrate the envelope. Floodproofing techniques 

are considered to be permanent measures if they are always in place 

and do not require any specific action to be effective. 

If located below the DFE, typical doors and windows present 

significant failure points. Special doors and window shields are 

available commercially and can be designed to provide protection 

against fairly deep floodwaters. The building must be specifically 

designed for these protective measures or loads may cause frames 

to separate from the building.

Use of contingent floodproofing measures that require installation or activation, such as window shields or inflatable barriers, 

significantly reduces the certainty that floodproofing will be effective. Rigorous adherence to a periodic maintenance plan is 

critical to ensure proper functioning. Not only must the school 

have a formal, written plan, but the people responsible for implementing the measures must be informed and trained. Also critical 

to success is that school personnel must receive a credible warning 

with sufficient time to allow getting to the site and putting the 

measures in place. In addition, floodproofing devices often rely 

on flexible seals that require periodic maintenance and that, over 

time, may deteriorate and become ineffective. Therefore, a maintenance plan must be developed and an annual inspection and 

training must be conducted. 

Safety of occupants remains a concern with floodproofed 

buildings. Regardless of the degree of protection provided, floodproofed buildings should not be occupied during flood events 

because failure or overtopping of the floodproofing measures is 

likely to cause catastrophic structural damage. When human intervention is required, the people responsible for implementing 

those measures remain at risk while at the school, even if a credible warning system is in place because of the many uncertainties 

associated with predicting the onset of flood conditions. 
MAKING SCHOOLS SAFE AGAINST FLOODS 5-33

5.5.4 Accessory Structures 

Depending on the nature of structures that are accessory to a 

school, full compliance with floodplain management regulations is 

required and is appropriate to minimize future damage. Buildings 

that serve educational purposes (e.g., offices, classrooms), even if 

detached from the primary school building, are not accessory in 

nature. Portable classrooms are not accessory structures; accessory 

structures commonly associated with schools include storage sheds, 

bleachers, garages, restrooms, and refreshment stands.

Accessory structures may be “wet floodproofed” using techniques 

that allow them to flood while minimizing damage. They must 

be anchored to resist flotation, collapse, and lateral movement. 

Flood-resistant materials must be used and utilities elevated above 

the DFE (plus freeboard, if required). Openings must be provided 

to allow the free inflow and outflow of floodwaters to minimize hydrostatic loads that cause structural damage. Other flood damage 

and flood loads must be accounted for by other means. Because 

wet floodproofed accessory buildings are designed to flood, 

school staff must be aware that contents will be damaged. 

5.5.5 Utility Installations 

Utilities associated with new schools in flood hazard areas must 

be protected either by elevation or special design measures. Utilities subject to this provision include all systems, equipment, and 

fixtures, including mechanical, electrical, plumbing, and heating, 

ventilating, and air conditioning systems and equipment. Potable 

water systems (wellheads and distribution lines) and wastewater 

collection lines are addressed in Section 5.7.6. 

Utility systems and equipment are best protected when elevated 

above the DFE (plus freeboard, if required). Equipment inside 

elevated buildings is also elevated and equipment inside accessory structures must be elevated if the accessory building is wet 

floodproofed. Exterior equipment must be elevated on fill or on 

platforms, or other support structures. Designers should pay par-
5-34 MAKING SCHOOLS SAFE AGAINST FLOODS 

ticular attention to underfloor utilities and ductwork to ensure 

that they are properly elevated.

Although it is difficult to achieve, the model building codes and 

NFIP regulations provide an alternative that allows utility systems 

and equipment to be located below the DFE. The alternative requires that such systems and equipment be designed, constructed, 

and installed to prevent floodwaters from entering or accumulating within the components during flood events.

5.5.6 Potable Water and Wastewater Systems

New installations of potable water systems and wastewater collection systems are required to resist flood damage, including 

damage associated with infiltration of floodwaters and discharge 

of effluent. Health concerns arise when water supply systems are 

exposed to floodwaters and contamination from flooded sewage 

systems pose health and environmental risks. On-site water supply 

wellheads should be protected with watertight casings to minimize 

infiltration of surface waters. 

Sewer collection lines should be located and designed to avoid infiltration and backup due to rising floodwaters. Devices designed 

to prevent backup are available and are recommended to provide 

an added measure of protection. 

On-site sewage disposal systems are unlikely for most new school 

construction. However, in the event such systems are considered, 

designers are advised that local or state health departments may 

impose constraints that limit or prevent locating septic fields in 

floodplain soils or within a mapped flood hazard area. If allowed, 

septic fields should be located on the highest available ground to 

minimize inundation and impairment by floodwaters. 

5.5.7 Storage Tank Installations 

Whether above ground or under ground, storage tanks located in 

flood hazard areas must be designed to resist flotation, collapse, 
MAKING SCHOOLS SAFE AGAINST FLOODS 5-35

and lateral movement. Aboveground tanks must be elevated or 

adequately anchored to account for maximum buoyancy under 

design flood conditions, assuming the tanks are empty. Similarly, 

underground tanks must be anchored for maximum buoyancy 

under design flood conditions, assuming the tanks are empty. In 

all cases, designers are cautioned to address hydrodynamic loads 

and debris impact loads that may affect tanks that are exposed to 

floodwaters. Vents and fill openings or cleanout accesses should 

be elevated above the DFE or designed to prevent the inflow of 

floodwaters or outflow of the contents of tanks. 

5.5.8 Access Roads 

Access roads to schools should be designed to minimize impacts 

on flood hazard areas, minimize damage to the road itself, and to 

minimize exposing vehicles to dangerous situations, although balancing those elements can be difficult, depending on the site and 

specific flood characteristics. Designers should take the following 

into consideration:

❍ Safety factors. Although a school’s access road is not required 

to carry regular traffic like other surface streets, a flood-prone 

road always presents a degree of risk to public safety. To 

minimize those risks, some regulatory authorities require that 

access roads be designed to be no more than 1 foot or 2 feet 

below the DFE. To maximize evacuation safety, two separate 

accesses to different feeder roads are recommended. In some 

circumstances, especially long-duration flooding where a school 

is built on fill, dry access may allow continued operations. 

❍ Floodplain impacts. Engineering analyses may be required 

to document effects on flood elevations and flow patterns if 

large volumes of fill are required to elevate a road to minimize 

dangerous flooding above the driving surface.

❍ Drainage structure and road surface design. The placement 

of multiple drainage culverts, even if not needed for local 

drainage, can facilitate the passage of floodwaters and 
5-36 MAKING SCHOOLS SAFE AGAINST FLOODS 

minimize the potential for a road embankment to act as a 

dam. Embankments should be designed to remain stable 

during high water and as waters recede, and should be sloped 

and protected to resist erosion and scour. For roads that 

are designed to flood, the surface and shoulders should be 

designed to resist erosion.

5.6 VULNERABILITY: WHAT FLOODS CAN 

DO TO EXISTING SCHOOLS

Existing flood-prone schools are exposed to damage, and the 

nature and severity of damage is a function of site-specific flood 

characteristics. As described below, damage may include: site 

damage; structural and nonstructural building damage; destruction or impairment of service equipment; loss of contents; and 

health and safety threats due to contaminated floodwater. 

Regardless of the nature and severity of damage, flooded schools 

are closed while cleanup and repairs are undertaken. The length 

of the closure, and thus the impact on the ability of the school 

district to return to teaching, depends on the severity of the 

damage and lingering health hazards. It may also depend on 

whether the building was fully insured or whether disaster assistance is made available quickly to allow speedy repairs and 

reconstruction. Sometimes repairs are put on hold pending 

a decision on whether a school should even be rebuilt at the 

flood-prone site. When damage is substantial, reconstruction is allowed only if compliance with flood-resistant design provisions is 

achieved (see Section 5.7.3).

5.6.1 Site Damage

The degree of site damage associated with flooding is a function 

of several variables related to the characteristics of the flood, as 

well the site itself:

❍ Erosion and scour. All parts of a school site that are subject to 

flooding by fast moving flows could experience erosion, and 

local scour could occur around any permanent obstructions 
MAKING SCHOOLS SAFE AGAINST FLOODS 5-37

to flow. Graded areas, filled areas, and cut or fill slopes are 

especially susceptible. Stream and channel bank erosion is 

a natural phenomenon that may, over time, threaten site 

improvements and buildings. 

❍ Debris and sediment removal. Even when buildings are not 

subject to flood damage, floods can produce large quantities 

of debris and sediment that can damage a site and that are 

expensive to remove, especially from athletic fields. 

❍ Fences. Some fences trap floating debris and can significantly 

restrict the free flow of floodwaters. Fences can be damaged 

by flowing water and can be flattened if the buildup of debris 

results in significant loads. 

❍ Playing field surfaces. In addition to damage by erosion and 

scour, graded grass fields and applied track surfaces can be 

damaged by standing water and deposited sediments. 

❍ Accessory structures. Accessory structures such as storage 

sheds, bleachers, restrooms, and refreshment stands can 

sustain both structural and nonstructural damage. Such 

structures may be designed and built using techniques that 

minimize damage potential. 

❍ Access roads. Access roads that extend across flood-prone 

areas may be damaged by erosion, washout of drainage 

culverts, failure of fill materials, and loss of surface. 

❍ Other. Objects outside of buildings, including cars and school 

buses, can be damaged or washed away.

5.6.2 Structural Damage

Structural damage includes all damage to the load-bearing portions of a building. Damage to other components of buildings is 

described below: finish materials (Section 5.6.3), utility service 

equipment (Section 5.6.4), and contents (Section 5.6.5). Struc-
5-38 MAKING SCHOOLS SAFE AGAINST FLOODS 

tural damage can be caused by each of the characteristics of 

flooding described in Section 5.2.1:

❍ Depth. The hydrostatic load or pressure against a wall 

or foundation is directly related to the depth of water 

(see Figure 5-7). Standard stud and siding, or brick faced 

walls, may collapse under hydrostatic loads associated with 

relatively shallow depths of water. Reinforced masonry walls 

perform better than unreinforced masonry walls, although an 

engineering analysis is required to determine performance. 

Walls and floors of below-grade areas (basements) are 

particularly susceptible to damage by hydrostatic pressure. 

When soils are saturated, pressures against below-grade walls 

are a function of the total depth of water, including the 

depth below-grade and the weight of the saturated soils.

❍ Buoyancy and uplift. If below-grade areas are essentially 

watertight, buoyancy or uplift forces can rupture concrete 

floors or float a building out of the ground (see Figure 5-8). 

Flood-prone buildings that are not adequately anchored can 

be floated or pushed off foundations. Although rare for large 

and heavy school buildings, this is a concern for outbuildings 

and portable (temporary) classrooms.

❍ Duration. Long duration saturation can cause dimensional 

changes and contribute to deterioration of wood members, 

although saturation is unlikely to result in significant 

structural damage to masonry construction. Saturation of 

soils, a consequence of long duration flooding, increases 

pressure on below-grade foundation walls. 

❍ Velocity, wave action, and debris impacts. Each of these 

components of dynamic loads can result in structural damage 

if buildings are not designed to resist overturning, repetitive 

pounding by waves, or short-duration impulsive loads 

generated by floating debris or ice.
MAKING SCHOOLS SAFE AGAINST FLOODS 5-39

Figure 5-7 Hydrostatic force diagram

Figure 5-8 

Fractured concrete basement floor, Gurnee, IL, 

1986
5-40 MAKING SCHOOLS SAFE AGAINST FLOODS 

❍ Erosion and scour. Structural damage is associated with 

foundation failure when erosion or scour results in partial 

or complete removal of supporting soil. Erosion of slopes, 

especially unprotected slopes, can lead to slope failures and 

loss of foundation supporting soil. 

5.6.3 Saturation Damage

Many flood-prone buildings are exposed to flooding that is not 

fast moving or that may be relatively shallow and not result in 

structural damage. Simple saturation of the building and its furnishings can result in significant and costly damage, including 

long-term health complications associated with mold. Floodwaters often are contaminated with chemicals or petroleum 

products. Under such circumstances, recovery generally involves 

removal of nonstructural materials and finishes because cleanup 

and decontamination is expensive and time-consuming. Damage 

to contents is discussed in Section 5.6.5. 

Saturation damage varies somewhat as a function of duration. 

Use of water-resistant materials will help to minimize saturation 

damage and reduce the costs of cleanup and restoration to service (see Flood-Resistant Materials Requirements, FIA-TB-2): 

❍ Wall finishes. Painted concrete and concrete masonry walls 

usually resist water damage, provided the type of paint 

used can be readily cleaned. Tiled walls may be acceptable, 

depending on the type of adhesive and foundation (gypsum 

board substrate and wood-framed walls with tile typically do 

not remain stable). 

❍ Flooring. Most schools have durable floors that resist water 

damage. Ground floors typically are slab-on-grade and 

finished with tile or sheet goods. Flooring adhesives since 

the early 1990s likely are latex-based and tend to break 

down when saturated. Most carpeting, even indoor-outdoor 

materials, are difficult to clean. Wood floors are particularly 

susceptible to saturation damage. Short duration inundation 
MAKING SCHOOLS SAFE AGAINST FLOODS 5-41

may not cause permanent deformation of some wood floors, 

such as may be present in older buildings. However, because 

of low tolerance for surface variations, gymnasium floors are 

particularly sensitive and tend to warp after flooding of any 

duration. 

❍ Wall and wood components. When soaked for long periods 

of time, some building components change composition 

or shape. Wet wood will swell and, if dried too quickly, will 

crack, split or warp. Plywood can delaminate and wood door 

and window frames may swell and become unstable. Gypsum 

wallboard, wood composition panels, other wall materials, and 

wood cabinetry not intended for wet locations can fall apart 

(see Figure 5-9). The longer these materials are wet, the more 

moisture, sediment, and pollutants they will absorb. Some 

wall materials such as the paper facing on gypsum wallboard, 

“wick” standing water, resulting in damage above the actual 

high-water line (see Figure 5-10).

❍ Metal components. Metal structural components are unlikely 

to be permanently damaged by inundation. Metal partitions 

are particularly susceptible when saturated because they 

cannot be thoroughly dried and cleaned. Depending on 

the degree of corrosion protection on the metal, repetitive 

flooding by saline coastal waters may contribute to long-term 

corrosion.

❍ Metal connectors and fasteners. Depending on the 

composition of the metal, repetitive flooding, especially by 

saline coastal waters, may contribute to long-term corrosion. 

Connectors and fasteners are integral to the structural stability 

of buildings, therefore, failure due to accelerated corrosion 

would jeopardize the building.
5-42 MAKING SCHOOLS SAFE AGAINST FLOODS 

Figure 5-9 

Damaged walls and 

cabinets, Peoria County, IL

Figure 5-10 

Basement damage at a 

grade school in Gurnee, 

IL, 1986

5.6.4 Utility System Damage

Utility system service equipment that is exposed to flooding is vulnerable to damage. Damage may result in total loss or may require 

substantial cleaning and restoration efforts. The degree of damage 

varies somewhat as a function of flooding characteristics. Certain 
MAKING SCHOOLS SAFE AGAINST FLOODS 5-43

types of equipment and installation measures will help to minimize damage and to reduce the costs of cleanup and restoration 

to service: 

❍ Displacement of equipment and appliances. Installation below 

the flood level exposes equipment and appliances to various 

flood forces, including drag due to flowing water and buoyancy. 

Gas-fired appliances are particularly dangerous: flotation 

can separate the appliance from the gas source, resulting in 

building fires, and explosive situations. Displaced equipment 

may dislodge lines from fuel oil tanks, not only contributing 

to the threat of fires, but also causing water pollution and 

environmental damage. Firefighting efforts are compounded if 

access to the school is limited due to flooded roads.

❍ Corrosion. Corrosion related to inundation of equipment and 

appliances may not be apparent immediately, but can increase 

maintenance demand and shorten the useful life of some 

equipment and appliances. 

❍ Electrical systems and components. Electrical systems and 

components, and electrical controls of HVAC systems, are 

subject to damage simply by getting wet even for short 

durations. Unless specifically designed for wet locations, 

switches and other electrical components can short out due 

to deposits of sediment or otherwise not function even when 

allowed to dry before operation. Wiring and components that 

have been submerged may be functional, although generally 

it is more cost-effective to discard flooded outlets, switches, 

and other less expensive components than to attempt 

thorough cleaning.

❍ Ductwork damage. Ductwork is subject to two flood-related 

problems. Flood forces can displace ductwork and saturated 

insulation can overload support straps, causing failure.

❍ Mold and dust. Furnaces, air handlers, and ductwork 

that have been submerged must be thoroughly cleaned 
5-44 MAKING SCHOOLS SAFE AGAINST FLOODS 

and sanitized. Otherwise, damp conditions contribute to 

the growth of mold and the sediment can be circulated 

throughout the school, causing respiratory problems.

❍ Gas-fired systems. Water-borne sediment can impair safe 

functioning of jets and controls in gas-fired furnaces and 

water heaters, necessitating that they be professionally cleaned 

and inspected prior to restoration of service.

❍ Tanks (underground). Underground storage tanks are subjected 

to significant buoyant forces and can be displaced, especially 

when long-duration flooding occurs. Computations of stability 

should be based on the assumption that the tank is empty in 

order to maximize safety. Tank inlets, fill openings, and vents 

should be above the DFE or designed to prevent the inflow of 

floodwaters or outflow of tank contents during flood conditions.

❍ Tanks (aboveground). Aboveground storage tanks are subject 

to buoyant forces and displacement due to moving water. 

Standard strapping of propane tanks may be inadequate for 

the anticipated loads. Tank inlets, fill openings, and vents 

should be above the design flood elevation or designed to 

prevent the inflow of floodwaters or outflow of tank contents 

during flood conditions.

Damage to public utility service (potable water supply and wastewater collection) can have consequential damage to schools:

❍ Water supply. Potable water supply systems may become 

contaminated if public water distribution lines or treatment 

facilities are damaged, or if wellheads are submerged.

❍ Sewer backup. Sewers back up during heavy rains due to 

infiltration and inflow of stormwater into the sewer lines and 

manholes, cross connections between storm and sanitary sewers, 

and/or flooded wastewater treatment plants. Sewer backup into 

a school poses a major health hazard. Even when the water has 

receded, exposed building components, finish materials, and 
MAKING SCHOOLS SAFE AGAINST FLOODS 5-45

contents are severely contaminated and usually must be removed 

because adequate cleaning is difficult, if not impossible. 

5.6.5 Contents Damage

Schools may contain high value contents that can be damaged and 

unrecoverable when subjected to flooding. For the purpose of this 

discussion about the nature of flood-related contents damage, the 

term “contents” includes furniture, computers, laboratory equipment and materials, records, and library materials. The following 

types of contents often are considered total losses: 

❍ Furniture. Depending on the nature of wood furniture, it may 

withstand short-duration inundation, requiring only cleanup. 

In long-duration flooding, porous woods become saturated 

and swollen, and joints may separate. Furniture with coverings 

or pads generally cannot be restored. Metal furniture is 

difficult to thoroughly dry and clean, is subject to corrosion, 

and typically is discarded.

❍ Computers. Flood damaged computers and peripheral 

equipment cannot be restored after inundation, although 

special recovery procedures may be able to recover 

information on hard drives.

❍ School records. When offices are located in flood-prone 

space, valuable school records may be lost. Although 

expensive, some recovery of computerized and paper records 

may be possible with special procedures.

❍ Library books and collections. It is generally not economical 

to recover library materials and special collections that are 

saturated by floodwaters. 

❍ Laboratory materials and equipment. Depending on the 

nature of laboratory materials, cleanup may require special 

procedures. Generally, equipment is difficult to restore to 

safe functioning.
5-46 MAKING SCHOOLS SAFE AGAINST FLOODS 

❍ Kitchen goods and equipment. Stainless steel equipment 

and surfaces generally have cleanable surfaces that 

can be disinfected and restored to service. Because of 

contamination, kitchen contents and perishables cannot be 

recovered. 

5.7 RISK REDUCTION: PROTECTING 

EXISTING SCHOOLS

Schools that already are located in flood hazard areas may be 

made more resistant to flood damage. School districts may take 

such action when flood hazards are identified and there is a desire to proactively 

undertake risk reduction measures. Interest 

may be prompted by a flood or by the requirement to address flood resistance as part 

of proposed substantial improvements or 

additions. Table 5-2 offers some questions to 

help identify building characteristics that are 

important when considering risk reduction 

measures.

Work on existing school buildings and sites 

is subject to codes and regulations and the 

appropriate regulatory authority with jurisdiction should be consulted. With respect to 

reducing flood risks, work generally falls into the following categories described in Sections 5.7.1 though 5.7.8.

School districts should be aware of the 

importance of flood insurance for floodprone existing schools. If not insured for 

flood peril, the amount of flood insurance 

coverage that should have been in place 

will be deducted from any federal disaster 

assistance payment that would otherwise 

have been made available. A district 

may have to absorb up to $1 million in 

unreimbursed flood damage per building 

because the NFIP offers $500,000 in 

building coverage and $500,000 in 

contents coverage.
MAKING SCHOOLS SAFE AGAINST FLOODS 5-47

Table 5-2: Characteristics of Existing School Buildings

Question Guidance

What is the construction type and the 

foundation type and what are their bearing 

capacities?

Dry floodproofing creates large unbalanced forces that can jeopardize walls and 

foundations that are not designed to resist the hydrostatic and hydrodynamic loads.

Is the building suitable for elevation-in-place 

or relocation to higher ground?

Elevating a building provides a higher degree of protection than dry floodproofing. 

Depending on the type and soundness of the foundation, even large buildings can be 

elevated or relocated.

Are any building spaces below-grade 

(basements)?

Below-grade spaces and their contents are most vulnerable. If flooding is allowed, 

rapid pump out can unbalance forces if the surrounding soil is saturated, leading to 

structural failure. If intended to be dry floodproofed, buoyant forces must be taken into 

consideration.

What types of openings penetrate the 

building envelope below the DFE (doors, 

windows, cracks, vent openings, plumbing 

fixtures, floor drains, etc.)?

For dry floodproofing to be effective, every opening must be identified and measures 

taken to permanently seal or to prepare special barriers to resist infiltration. Sewage 

backflow can enter through unprotected plumbing fixtures.

Are utility systems and HVAC equipment 

(including ductwork) below the DFE?

Relocating utility equipment to higher floors or elevated additions or platforms 

minimizes damage and facilitates rapid reoccupancy.

Are electrical panels and primary service 

below the DFE? Is the emergency power 

generator?

Relocating electrical panels to higher floors or elevated additions or platforms 

minimizes damage and facilitates rapid reoccupancy.
5-48 MAKING SCHOOLS SAFE AGAINST FLOODS 

5.7.1 Site Modifications 

Modifying an existing school property that is subject to flooding 

requires careful examination by an experienced professional 

engineer. Determining the suitability of a specific measure 

requires a complex evaluation of many factors, including the nature of flooding and the nature of the site. Table 5-1 identifies 

questions to be examined relative to flood hazards that influence the measures that may be applicable to modifying existing 

school sites. Some characteristics may make it infeasible to apply 

flood-resistant measures to existing schools (e.g., depths greater 

than 3 to 4 feet, very high velocities, flash flooding or rapid rate 

of rise [insufficient warning], and very long duration). Each of 

these measures has limitations, including the fact that the level 

of protection will be exceeded by floods that are larger than the 

design flood.

Site modifications may be designed to keep water away from 

a building. In each case, careful attention must be given to 

internal drainage. The rain that falls on the school and the 

portion of the site inside these flood protection measures 

will collect and must be accounted for or it may contribute 

to damage. Two general approaches are taken: provide sufficient ponding storage capacity or install pumps to transfer 

accumulated runoff outside the protection measure. Site modifications include:

❍ Regrading the site (berm). Where 

a school is exposed to relatively 

shallow flooding and sufficient land 

area is available, regrading the site 

or construction of a non-engineered 

earthen berm may provide adequate 

protection.

❍ Earthen levee or dike. Earthen levees are engineered 

structures that are designed to keep water away from land 

area and buildings (Figure 5-11). Hydraulic evaluations 

Schools protected by local berms, levees, 

and floodwalls should never be occupied 

during flood conditions. The consequences 

of failure or flood levels overtopping these 

measures can be catastrophic and create 

high-risk conditions. 
MAKING SCHOOLS SAFE AGAINST FLOODS 5-49

and geotechnical investigations are required to determine 

their feasibility and effectiveness. For existing school sites, 

constraints include the availability of land (levees have a 

large “footprint” and require large land areas), cost (including 

availability of suitable fill material and long-term maintenance), 

and difficulties with site access. Levees rarely are used to protect 

a single site, although they may offer a reasonable solution for 

a group of buildings. Locating levees and floodwalls within 

a designated floodway generally is not allowed. Rapid onset 

flooding makes it impractical to design a flood levee with access 

points that require installation of a closure system. Earthen 

levees may also be subject to high velocity flows that cause 

erosion and affect the stability of earthen levees. 

Figure 5-11 

Schematic of typical 

earthen levee and 

permanent floodwall
5-50 MAKING SCHOOLS SAFE AGAINST FLOODS 

❍ Permanent floodwall. Floodwalls are freestanding, 

permanent engineered structures that are designed to 

prevent encroachment of floodwaters. Typically, floodwalls 

are located at some distance from buildings so that 

structural modification of the existing building is not 

required. Floodwalls may protect only the low side of a 

site (in which case they must “tie” into high ground) or 

completely surround a site (which may affect access because 

special closure structures are required and must be installed 

before the on-set of flooding, Figure 5-12).

Figure 5-12 

Masonry floodwall with 

multiple engineered closures 

at Oak Grove Lutheran 

School, Fargo, ND

SOURCE: FLOOD CONTROL 

AMERICA, LLC.

❍ Mobilized floodwall. This category of flood protection 

measures includes fully engineered flood protection structures 

that have permanent features (foundation and vertical 

supports) and features that require human intervention to 

mobilize when a flood is predicted (horizontal components 

called planks or stop-logs). Mobilized floodwalls have been 

used to protect entire sites or to tie into permanent floodwalls 

or high ground. Due to the manpower and time required 

for proper placement, these measures are better suited to 

locations with sufficient warning times.

A common problem associated with the site modifications listed 

above is access. Depending on the topography of the site, construction of barriers to floodwaters may require special access 
MAKING SCHOOLS SAFE AGAINST FLOODS 5-51

points. Access points may be protected with manually installed 

stop-logs or designed gates that drop-in, slide, or float into 

place. Whether activated by automatic systems or manually, access protection requires sufficient warning time.

Other significant constraining factors include poor soils and 

insufficient land area. These also make site modifications either infeasible or very costly. A school may be among several 

buildings and properties that can be protected, increasing the 

benefits. For any type of barrier, rainfall that collects on the 

land side must be accounted for in the design.

5.7.2 Additions 

The model building codes treat additions as new construction. 

Therefore, additions to existing schools that are located in flood 

hazard areas are required to comply with the code. Elevation 

of an addition on fill may not be feasible unless structural fill 

can be placed adjacent to an existing building. Section 5.5.2 

outlines other elevation options that are applicable to additions. 

Utility service equipment for the addition must also meet the 

requirements for new construction and new installations (see 

Section 5.5.5).

With respect to code compliance and designing additions to 

resist flood damage, one of the more significant issues that may 

come up is ease of access. If the lowest floor of the existing 

school building is below the DFE, steps, ramps, or elevators will 

be required for the transition to the new addition. Under the 

regulations of the NFIP and guidance that FEMA offers to jurisdictions that may wish to consider variances, it is not considered 

appropriate to grant a variance to the elevation requirement for 

an addition because alternative means of access are available. 
5-52 MAKING SCHOOLS SAFE AGAINST FLOODS 

5.7.3 Repairs, Renovations, and Upgrades

Every school that is considered for upgrades and renovations, or 

that is being repaired after substantial damage from any cause, 

must be examined for structural integrity 

and stability to determine compatibility with 

structural modifications that may be required 

to achieve acceptable performance. When an 

existing school is located in a flood hazard 

area, that examination should include consideration of measures to resist flood damage 

and reduce risks. 

The model building codes and the regulations 

of the NFIP and the model building codes 

require that work that constitutes ‘substantial 

improvement’ of an existing building be in 

compliance with the flood-resistant provisions of 

the code. Non-substantial improvements should 

take into account measures to reduce future 

flood damage, such as many described in Section 5.7.7 and wet floodproofing measures that allow water to enter the building to avoid 

structural damage, and emergency measures (see Section 5.7.8).

Compliance with flood-resistant provisions means the building 

must be elevated or dry floodproofed. Both options can be difficult for schools, given the typical size and complexity of school 

buildings. Dry floodproofing is described in Section 5.7.4 and is 

generally limited to water depths on the order of 3 to 5 feet. 

Elevating an existing building presents an entirely different set of 

challenges and also requires detailed structural engineering analyses. It involves the same equipment and methods used to move 

other types of buildings, and expert building movers have successfully moved large, heavy, and complex buildings, sometimes by 

segmenting them. A school building that is elevated-in-place must 

meet the same performance standards set for new construction 

(see Section 5.5).

Selected References: Flood Proofing: 

How to Evaluate Your Options (USACE, 

1993); Floodproofing Non-Residential 

Structures (FEMA 102); Non-Residential 

Floodproofing—Requirements and 

Certification (FIA-TB-3); and Engineering 

Principles and Practices for Retrofitting 

Flood-prone Residential Buildings (FEMA 

259). Although written primarily for homes, 

this last reference contains very detailed 

checklists and worksheets that can be 

modified for school buildings. They also 

provide some guidance for evaluating the 

costs and benefits of various measures. 
MAKING SCHOOLS SAFE AGAINST FLOODS 5-53

5.7.4 Retrofit Dry Floodproofing

Modifications of an existing building may be required, including 

construction of a reinforced supplementary wall, measures to 

counter buoyancy (especially if there is belowgrade space), installation of special watertight 

doors or barriers, and providing watertight 

seals around points of entry of utility lines. 

The details of structural investigations and 

structural design of such protection measures 

are beyond the scope of this manual. 

Detailed structural engineering evaluations are required to determine whether an existing building can be dry floodproofed due to 

the tremendous loads that may be exerted on a building not originally designed for such conditions. The following elements must 

be examined: 

❍ Structural strength of walls.

❍ The effects of buoyancy on below-grade areas.

❍ Protection where utilities enter the building; and the seepage 

of water through walls. Secondary walls can be constructed 

immediately adjacent to existing walls, with a waterproof 

membrane, to provide adequate strength. 

Application of waterproofing products or membranes may minimize infiltration of water through exterior walls, although there 

are limitations and concerns with durability. Measures that require 

human intervention are considered emergency measures and are 

discussed in Section 5.7.8. 

5.7.5 Utility Installations 

Some aspects of an existing school’s utility systems may be modified 

to reduce damage. The effectiveness of such measures depends 

not only on the nature of flooding, but the type of utility and the 

degree of exposure. Table 5-2 listed some questions that will help 

facility planners and designers to examine risk reduction measures.

Dry floodproofing refers to measures and 

methods to render a building envelope and 

utility systems substantially impermeable to 

floodwaters.
5-54 MAKING SCHOOLS SAFE AGAINST FLOODS 

Even if a school building is unlikely to sustain extensive structural 

damage due to flooding, high costs and delayed reoccupancy may 

result from flood-damaged utility systems. Risk reduction design 

measures can be applied whether undertaken as part of large-scale 

retrofits of existing schools or as separate projects:

❍ Relocate from below-grade areas. The most vulnerable utility 

installations are those located in below-grade areas, and the 

most effective protection measure is to relocate them to 

properly elevated sites or platforms that are at least 2 feet 

above the DFE. The complexity of re-routing pipes, conduits, 

ductwork, electrical service, lines, and connections will 

depend on site-specific factors.

❍ Elevate components. Whether located inside or outside of the 

building, some components of utility systems can be elevatedin-place on platforms, including electric transformers, water 

heaters, air conditioning compressors, furnaces, boilers, and 

heat pumps (see Figures 5-13 and 5-14). 

Figure 5-13 

Elevated electric 

transformer at an 

elementary school in 

Verret, LA

SOURCE: U.S. ARMY CORPS OF 

ENGINEERS, FLOOD-PROOFING 

SYSTEMS & TECHNIQUES, 1984
MAKING SCHOOLS SAFE AGAINST FLOODS 5-55

Figure 5-14 

Elevated utilities behind 

an elementary school in 

Wrightsville Beach, NC

❍ Anchor tanks and raise openings. Existing tanks can be elevated 

or anchored (both underground and aboveground tanks), as 

described in Section 5.5.7. If anchored below the DFE, tank 

inlets, vents, fill pipes, and openings should be elevated above 

the DFE or fitted with covers designed to prevent the inflow of 

floodwaters or outflow of the contents of the tanks.

❍ Protect components. If utility components cannot be 

elevated, it may be feasible to construct watertight enclosures 

or enclosures with watertight seals that require human 

intervention to install when flooding is predicted.

❍ Elevate control equipment. Control panels, gas meters, and 

electrical panels can be elevated, even if the equipment 

cannot be protected.

❍ Separate electrical controls. Where areas within an existing 

school are flood-prone, separation of control panels and 

electrical feeders will facilitate shutdown before floodwaters 

arrive and help protect the safety of workers during cleanup.
5-56 MAKING SCHOOLS SAFE AGAINST FLOODS 

5.7.6 Potable Water and Wastewater Systems

All plumbing fixtures that are connected to the potable water 

system may become weak points in the system if they allow floodwaters to contaminate the system. Relocating such uses to at least 

2 feet above the DFE provides protection. Wellheads can be sealed 

with watertight casings or protected with a sealed enclosure.

Wastewater system components become sources of contamination during floods. Rising floodwaters may force untreated 

sewage to backup through toilets. Specially designed back-flow 

devices can be installed or restrooms below the DFE can be provided with overhead piping that may require specially designed 

pumps in order to operate properly. Septic tanks can be sealed 

and anchored. 

5.7.7 Other Damage Reduction Measures 

A number of steps can be taken to make existing schools in flood 

hazard areas more resistant to flood damage, which also facilitates 

rapid recovery, cleanup, and reoccupancy. Whether these measures are applicable to a specific school depends, in part, on the 

characteristics of the flood hazard and the characteristics of the 

building itself. School facility planners and designers should consider the following:

❍ Retrofit the building envelope with openings specifically 

designed to allow floodwaters to flow in and out to minimize 

hydrostatic pressure on walls. Although allowing water to 

enter the building, this measure minimizes the likelihood of 

major structural damage. Walls that enclose interior spaces 

would also be retrofitted with openings.

❍ Replace interior walls that have cavities with flood-resistant 

construction or removable panels to facilitate cleanup and drying.

❍ Abandon use of below-grade areas (basements) by filling to 

prevent structural damage.
MAKING SCHOOLS SAFE AGAINST FLOODS 5-57

❍ Permanently relocate high-value uses that often are found 

on the ground floor of schools (e.g., offices, school records, 

libraries, and computer laboratories) to higher floors or 

elevated additions.

❍ Install backflow devices in sewer lines.

❍ Pre-plan actions to move damageable furniture and highvalue contents from lower floor to higher floors, when a flood 

warning is issued.

❍ Replace wall, flooring, and finish materials with flood-resistant 

materials. 

❍ Use epoxy or other impervious paints on concrete and other 

pervious surfaces to minimize contamination. 

❍ Install separate electric circuits and ground fault interrupter 

circuit breakers in areas that will flood. Emergency measures 

should be provided so that electrical service can be shut down 

to avoid electrocution hazards.

❍ Relocate chemicals to areas not subject to flooding.

5.7.8 Emergency Measures

Emergency response to flooding is outside the scope of this 

manual. However, because some existing schools may not be retrofitted to provide protection against the design flood, it may 

be appropriate to examine feasible emergency measures that 

may provide some protection. The following discussion pertains 

only to emergency measures that have been used to reduce 

flood damage to older buildings that are already located in flood 

hazard areas. These measures do not achieve compliance with 

building and life safety codes, do not provide protection to occupants, and experience a very high frequency of failure. 

Emergency barriers are measures of “last resort,” and should be 

used only when a credible flood warning with adequate leadtime is available and dependable. These measures have varying 

degrees of success, depending on the available manpower, skill 
5-58 MAKING SCHOOLS SAFE AGAINST FLOODS 

required, long-term maintenance of materials and equipment, 

suitability for site-specific flood conditions, and sufficiency of 

warning. Complete evacuation of protected buildings is required 

as these measures should not be considered adequate protection 

for occupants. Further, emergency barriers are not acceptable 

in lieu of designed flood resistant protection for new buildings. 

Typical examples include:

❍ Sandbag walls. Unless planned well in advance or emergency 

workers are under the direction of trained personnel, most 

sandbag barriers are not constructed in accordance with 

proper practices, leading to leakage and failures. Because 

of the intensive work effort and length of time required 

for protection from even relatively shallow water, sandbag 

walls are not a reliable protection measure. To be effective, 

sandbags and sand should be stockpiled and checked 

regularly to ensure the sandbags have not deteriorated. 

Sandbags have some drawbacks, including high disposal costs 

and their tendency to absorb pollutants from contaminated 

floodwaters.

❍ Water-filled barriers. A number of vendors make barriers 

that can be assembled with relative ease, depending on the 

source water for filling. The barriers must be specifically 

sized for the site. Training is important so that personnel 

know how to place and deploy the barriers. Proper storage, 

including cleaning after deployment, is necessary to protect 

the materials over long periods of time.

❍ Panels for doors. For shallow and short-duration flooding, 

plywood panels or panels of other sturdy material can be 

made for doorways to minimize the entry of floodwaters. 

Effectiveness is increased significantly if a flexible gasket or 

sealant is provided and the mounting hardware is designed 

to apply even pressure. Personnel must know where the 

materials are stored and be trained in deployment.
MAKING SCHOOLS SAFE AGAINST FLOODS 5-59

5.8 THE SCHOOL AS AN EMERGENCY 

SHELTER

Emergency managers regularly identify schools to serve as shortterm and/or long-term shelters. They are attractive sites for 

shelters because they have kitchen facilities that are designed 

to serve many people, restroom facilities that are likely to be 

adequate for many people, and space for cots in gymnasiums, cafeterias, and wide corridors.

New schools that are to be used for emergency sheltering are 

appropriately designed as essential or critical facilities that warrant a higher degree of protection than other schools. If located 

in or adjacent to flood hazard areas, it is appropriate to provide 

protection for the building and utility systems to at least the 

0.2%-annual chance (500-year) flood level or, at a minimum, 2 

to 3 feet above the DFE. Additional guidance on hazard-resistant 

shelters is found in FEMA 361, Design and Construction Guidance 

for Community Shelters. 

Additional measures that may be appropriate for consideration by 

the school district and designer include:

❍ Wastewater service must be functional during conditions of 

flooding.

❍ Emergency power service must be provided.

❍ Dry-ground access is important in the event flooding exceeds 

design levels.
5-60 MAKING SCHOOLS SAFE AGAINST FLOODS 

5.9 REFERENCES AND SOURCES OF 

ADDITIONAL INFORMATION

Obtaining Selected Publications: 

❍ FEMA publications may be obtained at no cost by calling 

(800)480-2520, faxing a request to (301)497-6378, or 

downloaded from the library/publications section online at 

http://www.fema.gov. 

❍ U.S. Army Corps of Engineers publications can be found 

online at: http://www.usace.army.mil/inet/functions/

cw/cecwp/NFPC/nfpc.htm.

American Society of Civil Engineers, Inc. Flood Resistant Design and 

Construction, ASCE/SEI 24-98, Reston, VA, 2000.

American Society of Civil Engineers, Inc. Minimum Design Loads 

for Buildings and Other Structures, ASCE-7-02, Reston, VA, 2002.

Federal Emergency Management Agency, Answers to Questions 

about Substantially Damaged Buildings, FEMA 213, Washington, DC, 

May 1991.

Federal Emergency Management Agency, Answers to Questions 

about the National Flood Insurance Program, FEMA 387, August 2001. 

Federal Emergency Management Agency, Coastal Construction 

Manual, FEMA 55 (3rd Edition), 2000.

Federal Emergency Management Agency, Design and Construction 

Guidance for Community Shelters, FEMA 361, Washington, DC, July 

2000.

Federal Emergency Management Agency, Engineering Principles 

and Practices for Retrofitting Flood-prone Residential Buildings, FEMA 

259, Washington, DC, January 1995.
MAKING SCHOOLS SAFE AGAINST FLOODS 5-61

Federal Emergency Management Agency, Floodproofing Non-Residential Structures, FEMA 102, Washington, DC, May 1986.

Federal Emergency Management Agency, Protecting Building Utilities From Flood Damage: Principles and Practices for the Design and 

Construction of Flood Resistant Building Utility Systems, FEMA 348, 

Washington, DC, November 1999. 

Federal Emergency Management Agency and American Red 

Cross, Repairing Your Flooded Home, FEMA 234/ARC 4477. Washington, DC. (available at http://www.redcross.org, local Red 

Cross chapters, and FEMA).

Federal Emergency Management Agency, NFIP Technical Bulletins:

❍ User’s Guide to Technical Bulletins, FIA-TB-0, April 1993. 

❍ Openings in Foundation Walls, FIA-TB-1, April 1993.

❍ Flood-Resistant Materials Requirements, FIA-TB-2, April 1993.

❍ Non-Residential Floodproofing—Requirements and Certification, 

FIA-TB-3, April 1993. 

❍ Elevator Installation, FIA-TB-4, April 1993. 

❍ Free-of-Obstruction Requirements, FIA-TB-5, April 1993. 

❍ Below-Grade Parking Requirements, FIA-TB-6, April 1993.

❍ Wet Floodproofing Requirements, FIA-TB-7, December 1993.

❍ Corrosion Protection for Metal Connections in Coastal Areas, FIATB-8, 1996.

❍ Design and Construction Guidance for Breakaway Walls Below 

Elevated Coastal Buildings, FIA-TB-9, 1999.

 ❍ Ensuring That Structures Built on Fill In or Near Special Flood 

Hazard Areas Are Reasonably Safe From Flooding, FIA-TB-10, 

2001. 

❍ Crawlspace Construction for Buildings Located in Special Flood 

Hazard Areas, FIA-TB-11, 2001.
5-62 MAKING SCHOOLS SAFE AGAINST FLOODS 

International Code Council, Inc. ICC Performance Code for Buildings and FacilitiesTM, Country Club Hills, IL, 2003.

International Code Council, Inc. International Building Code®, 

Country Club Hills, IL, 2003.

National Fire Protection Association. Building Construction and 

Safety Code (NFPA 5000), Quincy, MA, 2003. 

U.S. Army Corps of Engineers, Flood-Proofing Systems & Techniques, 

1984.

U.S. Army Corps of Engineers, Flood-Proofing Regulations, EP 1165-

2-314, 1992.

U.S. Army Corps of Engineers, National Flood-Proofing Committee, 

Flood-Proofing – How To Evaluate Your Options, Washington, DC, 

July 1993.

U.S. Army Corps of Engineers, Flood-Proofing Programs, Techniques 

and References, Washington, DC, 1996.

U.S. Army Corps of Engineers, Flood-Proofing Performance - Successes 

& Failures, Washington, DC, 1998.

Organizations and Agencies

Federal Emergency Management Agency: 10 regional offices 

(www.fema.gov) can be contacted for advice and guidance on 

NFIP mapping and regulations. 

NFIP State Coordinating offices help local governments to meet 

their floodplain management obligations and may provide technical advice to others; the offices are listed by the Association 

of State Floodplain Managers, Inc., (www.floods.org/

stcoor.htm). 
MAKING SCHOOLS SAFE AGAINST FLOODS 5-63

State departments of education or agencies that coordinate state 

funding and guidelines for schools may have state-specific requirements.

U.S. Army Corps of Engineers: District offices offer Flood Plain 

Management Services (www.usace.army.mil/inet/functions/

cw/). 

5.10 GLOSSARY OF FLOOD PROTECTION 

TERMS

Base flood. The flood having a 1 percent chance of being equaled 

or exceeded in any given year; sometimes referred to as the 100-

year flood.

Base flood elevation (BFE). The height of the base (1 percent or 

100-year) flood in relation to a specified datum, usually the National Geodetic Vertical Datum of 1929 or the North American 

Vertical Datum of 1988. 

Design flood. The greater of the following two flood events: (1) 

the base flood, affecting those areas identified as special flood 

hazard areas on a community’s Flood Insurance Rate Map 

(FIRM); or (2) the flood corresponding to the area designated as 

a flood hazard area on a community’s flood hazard map or otherwise legally designated.

Design flood elevation (DFE). The elevation of the design flood, 

including wave height, relative to the datum specified on a community’s flood hazard map.

Dry floodproofing. An adjustment, modification, or addition of a 

feature or combinations of these that eliminate or reduce the potential for flood damage by sealing walls and closing openings to 

keep water from entering a building. 

FEMA. Federal Emergency Management Agency, the federal agency 

that administers the National Flood Insurance Program (NFIP).
5-64 MAKING SCHOOLS SAFE AGAINST FLOODS 

Flood Insurance Rate Map (FIRM). Insurance and floodplain 

management map issued by FEMA that identifies areas of base 

flood hazard in a community. Some areas’ maps also include base 

flood elevations, 500-year floodplain boundaries, and regulatory 

floodway boundaries.

Flood Insurance Study (FIS). Engineering study performed by 

FEMA to identify flood hazard areas, flood insurance risk zones, 

and other flood data in a community; used in the development of 

the FIRM.

Floodplain. The area including a watercourse and the land adjacent to it that is flooded during a flood of a given recurrence 

interval (e.g., 10-year flood, 50-year flood, 100-year flood, etc.).

Floodplain management regulations. Zoning ordinances, subdivision regulations, building codes, health regulations, or 

special-purpose ordinances, that set flood protection standards for 

new construction and land use.

Floodway. The stream channel and that portion of the adjacent 

floodplain that must remain open to permit passage of the base 

flood. 

Freeboard. The additional height to which a building is protected 

from flooding above the base flood elevation to provide additional 

factor of safety and to account for uncertainties, usually 1 to 3 feet 

for critical/essential facilities. 

Human intervention. Actions that must be taken by one or more 

persons in order for a building to be floodproofed before floodwaters arrive. 

Hydrodynamic force. The force of moving water, including the 

impact of debris and high velocities. 
MAKING SCHOOLS SAFE AGAINST FLOODS 5-65

Hydrostatic pressure. The pressure put on a structure by the 

weight of standing water. The deeper the water, the more it weighs 

and the greater the hydrostatic pressure. 

Lowest floor. The lowest floor of the lowest enclosed area (including a basement) of a building. 

National Flood Insurance Program (NFIP). Federal program to 

identify flood-prone areas nationwide and make flood insurance 

available for properties in communities that participate in the 

program. 

Substantial damage. Damage to a building from any cause such 

that the cost to repair it to its pre-damaged condition is equal to 

50 percent or more of its pre-damaged value. 

Substantial improvement. A modification or remodeling of a 

building such that the value of the addition or remodeling is 

equal to 50 percent or more of the building’s original appraised 

value. 

Wet floodproofing. Permanent or contingent measures applied 

to a building and/or its contents that prevent or provide resistance to damage from flooding by modifying interior finishes, 

removing damageable items from lower areas, and allowing water 

into the building.

MAKING SCHOOLS SAFE AGAINST WINDS 6

MAKING SCHOOLS SAFE AGAINST WINDS 6-1

6.1 INTRODUCTION

Awell-designed, constructed, and maintained school 

may be damaged by a wind event that is much stronger 

than what the building was designed for; however, 

except for tornado damage, this scenario is a very rare occurrence. Rather, most damage occurs because various building 

elements have limited wind resistance due to inadequate design, 

application, or material deterioration. Wind with sufficient 

speed to cause damage to weak schools can occur anywhere in 

the United States and its possessions.1 Although the magnitude 

and frequency of strong windstorms varies by locale, all schools 

should and can be designed, constructed, and maintained to 

avoid wind damage (other than that associated with tornadoes). 

In tornado-prone regions, consideration should be given to 

designing and constructing portions of schools to provide occupant protection.2

This chapter discusses structural and nonstructural building 

components and illustrates a variety of wind-induced damages. 

Because of the frequency and significant consequences of nonstructural component failure, emphasis is given to these elements. 

Numerous examples of best practices pertaining to new and existing schools are presented for consideration. Incorporation of 

those practices that are applicable to a specific project will result 

in greater wind-resistance reliability and will, therefore, provide 

enhanced protection for occupants and decreased expenditures 

for repair of wind-damaged facilities. 

1 The U.S. possessions include American Samoa, Guam, Puerto Rico, and the U.S. Virgin Islands.

2 Tornado-prone regions are defined in Section 6.7.1.
6-2 MAKING SCHOOLS SAFE AGAINST WINDS 

6.2 THE NATURE AND PROBABILITY OF 

HIGH WINDS

A variety of windstorm types occur in different areas of the U.S. 

The characteristics of the type of storms that can impact the site 

should be considered by the design team. The primary storm 

types are:

❍ Straight-line wind. This type of wind event is the most 

common. The wind is considered, in general, to blow in a 

straight line. Straight-line wind speeds range from very low to 

very high. High winds associated with intense low pressure can 

last for upward of a day at a given location. Straight-line winds 

occur throughout the U.S. and its possessions (see Figure 6-1).

Figure 6-1 Hurricane-prone regions and special wind regions

Note: Hurricane/typhoon-prone regions also include American Samoa, Guam, Puerto Rico, and the U.S. Virgin Islands.

SOURCE: ADAPTED FROM ASCE 7-02
MAKING SCHOOLS SAFE AGAINST WINDS 6-3

❍ Down-slope wind. Wind flowing down the slope of mountains 

is referred to as down-slope wind. Down-slope winds with very 

high wind speeds frequently occur in Alaska and Colorado. 

In the continental U.S., mountainous areas are referred to 

as “special wind regions” (see Figure 6-1). Neither ASCE 7 or 

model building codes provide guidance on wind speeds in 

special wind regions. If the local building department has not 

established the basic speed, use of regional climatic data and 

consultation with a wind engineer or meteorologist is advised. 

❍ Thunderstorm. This type of storm can rapidly form and 

produce high wind speeds. Approximately 10,000 severe 

thunderstorms occur in the U.S. each year, typically in the 

spring and summer. They are most common in the Southeast 

and Midwest. Besides producing high winds, they often create 

heavy rain. Hail and tornadoes are also sometimes produced. 

Thunderstorms commonly move through an area quite 

rapidly, often causing high winds for only a few minutes at 

a given location. However, thunderstorms can also stall and 

become virtually stationary.

❍ Downburst. Also known as microburst, it is a powerful 

downdraft associated with a thunderstorm. When the 

downdraft reaches the ground, it spreads out horizontally and 

may form one or more horizontal vortex rings around the 

downdraft. The outflow is typically 6,000 to 12,000 feet across 

and the vortex ring may rise 2,000 feet above the ground. The 

life-cycle of a downburst is usually between 15 to 20 minutes. 

Observations suggest that approximately 5 percent of all 

thunderstorms produce a downburst, which can result in 

significant damage in a localized area.

❍ Northeaster (nor’easter). This type of storm is cold and violent 

and occurs along the northeastern coast of the U.S. These 

storms blow in from the Northeast and may last for several days.

❍ Hurricane. This is a system of spiraling winds converging 

with increasing speed toward the storm’s center (the eye 
6-4 MAKING SCHOOLS SAFE AGAINST WINDS 

of the hurricane). Hurricanes form over warm oceans. The 

diameter of the storm varies between 50 and 600 miles. A 

hurricane’s forward movement (translational speed) can 

vary between approximately 10 to 25 miles per hour (mph). 

Besides being capable of delivering extremely strong winds 

for several hours, many hurricanes also bring very heavy 

rainfall. Hurricanes also occasionally spawn tornadoes. 

The Saffir-Simpson Hurricane Scale rates the intensity of 

hurricanes. The five-step scale ranges from Category I (the 

weakest) to Category V (the strongest). Hurricane-prone 

regions are defined in Section 6.2.1.

Of all the storm types, hurricanes have the greatest potential 

for devastating a very large geographical area and, hence, 

affect great numbers of people. The terms “hurricanes, 

tropical cyclones, and typhoons” are synonymous for the same 

type of storm. See Figure 6-1 for hurricane-prone regions.

❍ Tornado. This is a violently rotating column of air extending 

from the base of a thunderstorm to the ground. The 

Fujita scale categorizes tornado severity based on observed 

damage. The six-step scale ranges from F0 (light damage) 

to F5 (incredible damage). Weak tornadoes (F0 and F1) are 

most common, but strong tornadoes (F2 and F3) frequently 

occur. Violent tornadoes (F4 and F5) are rare. Tornado 

path widths are typically less than 1,000 feet; however, widths 

of approximately 1 mile have been reported. Wind speed 

rapidly decreases with increased distance from the center of 

a tornado. A school on the periphery of a strong or violent 

tornado could be subjected to moderate to high wind speeds, 

depending upon the distance from the core of the tornado. 

However, even though the wind speed might not be great, a 

school on the periphery could still be impacted by many large 

pieces of wind-borne debris. Tornadoes are responsible for 

the greatest number of wind-related deaths each year in the 

U.S. Figure 6-2 shows frequency of occurrence for 1950 to 

1998 and Figure 6-3 shows the design wind speeds used for 

the design of community tornado shelters.
MAKING SCHOOLS SAFE AGAINST WINDS 6-5

Figure 6-2 Tornado occurrence in the United States based on historical data

SOURCE: FEMA 361, DESIGN AND CONSTRUCTION GUIDANCE FOR COMMUNITY SHELTERS, 2000
6-6 MAKING SCHOOLS SAFE AGAINST WINDS 

6.2.1 Wind/Building Interactions 

When wind interacts with a building, both positive and negative 

(i.e., suction) pressures occur simultaneously (see Figure 6-4). 

(Note: negative pressures are less than ambient pressure, and 

positive pressures are greater than ambient pressure.) The school 

must have sufficient strength to resist the applied loads in order to 

prevent wind-induced building failure. The magnitude of the pressures is a function of the following primary factors:

❍ Exposure. The characteristics of the ground roughness and 

surface irregularities in the vicinity of a building influence 

Figure 6-3 Design wind speeds for community tornado shelters 

SOURCE: FEMA 361, DESIGN AND CONSTRUCTION GUIDANCE FOR COMMUNITY SHELTERS, 2000
MAKING SCHOOLS SAFE AGAINST WINDS 6-7

the wind loading. ASCE 7 defines three exposure categories, 

Exposures B, C, and D.3 Exposure B is the roughest terrain 

and Exposure D is the smoothest. Exposure B includes urban, 

suburban, and wooded areas. Exposure C includes flat open 

terrain with scattered obstructions and areas adjacent to 

water surfaces in hurricane-prone regions (which are defined 

below under “basic wind speed”). Exposure D includes areas 

adjacent to water surfaces outside hurricane-prone regions, 

mud flats, salt flats, and unbroken ice. Because of the wave 

conditions generated by hurricanes, areas adjacent to water 

surfaces in hurricane-prone regions are considered to be 

Exposure C rather than the smoother Exposure D.

The smoother the terrain, the greater the wind load; 

therefore, schools (with the same basic wind speed) located 

in Exposure D would receive higher wind loads than those 

located in Exposure C. 

Figure 6-4 

Schematic of wind-induced pressures on a building

For additional information, see the Commentary of ASCE 7, which 

includes several aerial photographs that illustrate the different 

terrain conditions associated with Exposures B, C, and D.

3 Chapter 6 of ASCE 7 provides guidance for determining wind loads on buildings. The IBC and 

NFPA 5000 refer to ASCE 7 for wind load determination.
6-8 MAKING SCHOOLS SAFE AGAINST WINDS 

❍ Basic wind speed. ASCE 7 defines the basic wind speed as the 

wind speed with a 50-year mean recurrence interval (2 percent annual probability), measured at 33 feet above grade in 

Exposure C (flat open terrain). If the building is located in 

Exposure B or D, rather than C, an adjustment for the actual 

exposure is made in the ASCE 7 calculation procedure.

Since the 1995 edition of ASCE 7, the basic wind speed has 

been a peak gust speed. Prior to that time, the basic wind 

speed was a fastest-mile speed (i.e., the speed averaged over 

the time required for a mile-long column of air to pass a fixed 

point). Because the measuring time for peak gust versus fastest-mile is different, peak gust speeds are typically about 20 

miles per hour (mph) faster than fastest-mile speeds (e.g., a 

90-mph peak basic wind speed is equivalent to a 70-mph fastest-mile wind speed). Most of the U.S. has a basic wind speed 

(peak gust) of 90 mph, but much higher speeds occur in Alaska and in hurricane-prone regions. The highest speed, 170 

mph, occurs in Guam. 

Hurricane-prone regions are along the Atlantic and Gulf of 

Mexico coasts (where the basic wind speed is greater than 90 

mph), Hawaii, and the U.S. possessions in the Caribbean and 

South Pacific (see Figure 6-1).

In determining wind pressures, the basic wind speed is squared; 

therefore, as the velocity is increased, the pressures are exponentially increased. For example, the uplift load on a 30-foot 

high roof covering at a corner area of a school in Exposure B is 

37.72 pounds per square foot (psf) with a basic wind speed of 

85 mph (per ASCE 7-02). If the speed is doubled to 170 mph, 

the roof corner load increases by a factor of four to 151 psf.

❍ Topography. Abrupt changes in topography, such as isolated 

hills, ridges, and escarpments, cause wind speed-up; therefore, 

a school located near a ridge would receive higher wind loads 

than a school located on relatively flat land. ASCE 7 provides 

a procedure to account for topographic influences.
MAKING SCHOOLS SAFE AGAINST WINDS 6-9

❍ Building height. Wind speed increases with height above 

the ground. Therefore, the taller the school, the greater 

the speed and, hence, the greater the wind loads. ASCE 7 

provides a procedure to account for building height.

❍ Internal pressure (i.e., building pressurization/

depressurization). Wind striking a building can cause either 

an increase in the pressure within the building (i.e., positive 

pressure), or it can cause a decrease in the pressure (i.e., 

negative pressure). Internal pressure changes occur because 

of the porosity of the building envelope. Porosity is caused 

by openings around doors and window frames, and by air 

infiltration through walls that are not absolutely airtight. A 

door or window left in the open position also contributes to 

porosity. 

 Wind striking an exterior wall exerts a positive pressure on 

the wall, which forces air through openings and into the 

interior of the building (this is analogous to blowing up a 

balloon). At the same time the windward wall is receiving 

positive pressure, the side and rear walls are receiving negative 

(suction) pressure; therefore, air within the building is being 

pulled out at openings in these other walls. As a result, if the 

porosity of the windward wall is greater than the combined 

porosity of the side and rear walls, the interior of the building 

is pressurized. But if the porosity of the windward wall is less 

than the combined porosity of the side and rear walls, the 

interior of the building is depressurized (this is analogous to 

letting air out of a balloon).

 When a building is pressurized, the internal pressure pushes 

up on the roof. This push from below the roof is combined 

with the suction above the roof, resulting in an increased 

wind load on the roof. The internal pressure also pushes on 

the side and rear walls. This outward push is combined with 

the suction on the exterior side of these walls. Therefore, a 

pressurized building increases the wind load on the side and 

rear walls (see Figure 6-5) as well as on the roof.
6-10 MAKING SCHOOLS SAFE AGAINST WINDS 

When a building is depressurized, the internal pressure pulls 

the roof down, which reduces the amount of uplift exerted on 

the roof. The decreased internal pressure also pulls inward on 

the windward wall, which increases the wind load on that wall 

(see Figure 6-6).

Figure 6-5 

Schematic of internal 

pressure condition when 

the dominant opening is 

in the windward wall
MAKING SCHOOLS SAFE AGAINST WINDS 6-11

When a school becomes fully pressurized (e.g., due to window 

breakage), the loads applied to the exterior walls and roof are 

significantly increased. The build-up of high internal pressure can 

also blow down interior partitions and blow ceiling boards out of 

their support grid. The breaching of a small window is typically 

sufficient to cause full pressurization of the school’s interior.

Figure 6-6 

Schematic of internal 

pressure condition 

when the dominant 

opening is in the 

leeward wall
6-12 MAKING SCHOOLS SAFE AGAINST WINDS 

ASCE 7 provides a design procedure to assess the influence 

of internal pressure on the wall and roof loads, and it 

provides positive and negative internal pressure coefficients 

for use in load calculations. Buildings that can be fully 

pressurized are referred to as partially enclosed buildings. 

Buildings that have limited internal pressurization capability 

are referred to as enclosed buildings. 

❍ Aerodynamic pressure. Because of building aerodynamics 

(i.e., the interaction between the wind and the building), the 

highest uplift loads occur at roof corners. The roof perimeter 

has a somewhat lower load, followed by the field of the roof. 

Exterior walls typically have lower loads than the field of the 

roof. The ends of walls have higher suction loads than the 

portion of wall between the ends. However, when the wall 

is loaded with positive pressure, the entire wall is uniformly 

loaded. Figure 6-7 illustrates these aerodynamic influences. 

The negative values shown in Figure 6-7 indicate suction 

pressure acting upward from the roof surface and outward 

from the wall surface. Positive values indicate positive pressure 

acting inward on the wall surface.

Aerodynamic influences are accounted for by use of external 

pressure coefficients, which are used in load calculations. 

The magnitude of the coefficient is a function of the 

location on the building (e.g., roof corner or field of roof) 

and building shape as discussed below. Positive coefficients 

represent a positive pressure, and negative coefficients 

represent negative (suction) pressure. External pressure 

coefficients are found in ASCE 7.

Building shape affects the magnitude of pressure coefficients 

and, therefore, the loads applied to the various building 

surfaces. For example, the uplift loads on a low-slope roof 

are larger than the loads on a gable or hip roof. The steeper 

the slope, the lower the uplift load. Pressure coefficients for 

monoslope (shed) roofs, sawtooth roofs, and domes are all 

different from those for low-slope and gable/hip roofs.
MAKING SCHOOLS SAFE AGAINST WINDS 6-13

Figure 6-7 

Relative roof uplift pressures as a function of roof geometry, roof slope, and location on roof, and 

relative positive and negative wall pressures as a function of location along the wall. 
6-14 MAKING SCHOOLS SAFE AGAINST WINDS 

Figure 6-9 

The metal roof is over a 

stair tower. The irregularity 

created by the stair tower 

caused turbulence that 

resulted in wind speed-up. 

Building irregularities such as bay window projections, a stair 

tower projecting out from the main wall, dormers, chimneys, 

etc., can cause localized turbulence. Turbulence causes wind 

speed-up, which increases the wind loads in the vicinity of the 

building irregularity as shown in Figures 6-8 and 6-9.

Figure 6-8 

The aggregate ballast on 

this single-ply membrane 

roof was blown away in 

the vicinity of the corners of 

the wall projections at the 

window bays. The irregular 

wall surface created 

turbulence, which led to 

wind speed-up and loss of 

aggregate in the turbulent 

flow areas. 
MAKING SCHOOLS SAFE AGAINST WINDS 6-15

As shown in Figure 6-9, the built-up roof’s base flashing was 

pulled out from underneath the coping and caused a large area 

of the membrane to lift and peel. Some of the wall covering on 

the stair tower was also blown away. Had the stair tower not existed, the built-up roof would not have been damaged.

Loads exerted on the building envelope are transferred to the 

structural system, where they are transferred through the foundation and into the ground.

Information pertaining to load calculations is presented in Section 6.8.2.

For further general information on the nature of wind and windbuilding interactions, see Buildings at Risk: Wind Design Basics for 

Practicing Architects, American Institute of Architects, 1997.

To avoid damage in the vicinity of building irregularities, attention needs to be given to attachment of building elements 

located in turbulent flow areas.

6.2.2 Probability of Occurrence

Most buildings are designed for a 50-year mean recurrence interval wind event (2 percent annual probability). A 50-year storm 

would be expected to happen about once every 50 years; however, 

a 50-year storm can occur more or less frequently. A 50-year storm 

may not occur within any 50-year interval, but two 50-year storms 

could occur within 1 year.

ASCE 7 requires schools with a capacity greater than 250 occupants and schools used for hurricane or other emergency shelters 

to be designed for a 100-year mean recurrence interval wind event 

(1 percent annual probability); therefore, these schools are designed to resist stronger, rarer storms than most buildings. The 

importance factor is used to adjust the mean recurrence interval. 

For a 50-year interval, the importance factor is 1.00. For a 100-year 

interval, the importance factor is 1.15. 
6-16 MAKING SCHOOLS SAFE AGAINST WINDS 

When designing a school, architects and engineers should consider the following:

❍ Routine winds. In many locations, winds with low to moderate 

speeds occur daily. Damage is not expected to occur during 

these events.

❍ Stronger winds. At a given site, stronger winds (e.g., winds with 

a basic wind speed in the range of 70 to 80 mph peak gust) 

may occur from several times a year to only once a year or less 

frequently. 70 to 80 mph is the threshold at which damage 

normally begins to occur to building elements that have 

limited wind resistance due to problems associated with

inadequate design, strength, application, or 

material deterioration.

❍ Design level winds. Schools that experience 

design level events and events that are 

somewhat in excess of design level should 

experience little, if any damage; however, 

design level storms frequently cause 

extensive building envelope damage. 

Structural damage also occurs, but less 

often. Damage experienced with design 

level events is typically associated with 

inadequate design, application, or material 

deterioration. The exceptions are winddriven water infiltration and wind-borne 

debris (missiles) damage. Water infiltration 

is discussed in Sections 6.10.4, 6.11.3, and 

6.13.3. 

❍ Tornadoes. Although more than 1,200 tornadoes typically 

occur each year in the U.S., the probability of a tornado occurring at any given location is quite small. The probability 

of occurrence is a function of location. As shown in Figure 

6-2, only a few areas of the U.S. frequently experience tornadoes, and tornadoes are very rare in the west. The Oklahoma 

Missile damage is very common during 

hurricanes and tornadoes. Missiles can 

puncture roof coverings, many types 

of exterior walls, and glazing. The 

IBC does not address missile-induced 

damage, except for glazing in windborne debris regions. (Wind-borne 

debris regions are limited to portions of 

hurricane-prone regions.) In hurricaneprone regions, significant school 

damage should be expected even 

during design level hurricane events, 

unless special enhancements are 

incorporated into the school’s design 

(see Section 6.15).
MAKING SCHOOLS SAFE AGAINST WINDS 6-17

Figure 6-10 

This high school in 

northern Illinois was 

heavily damaged by a 

strong tornado. 

City area is the most active location in the U.S., with 106 recorded tornadoes between the years 1890 and 2000. 

Except for window breakage, well designed, constructed, and 

maintained schools should experience little if any damage 

from weak tornadoes. However, because many schools 

have wind-resistance deficiencies, weak tornadoes often 

cause building envelope damage. Most schools experience 

significant damage if they are in the path of a strong or 

violent tornado (see Figure 6-10). In the classroom wing, 

shown in Figure 6-10, all of the exterior windows were 

broken, and virtually all of the cementitious wood-fiber deck 

panels were blown away. Much of the metal decking over 

the band and chorus area also blew off. The gymnasium 

collapsed, as did a portion of the multi-purpose room. The 

school was not in session at the time the tornado struck.

6.3 VULNERABILITY: WHAT WIND CAN DO 

TO SCHOOLS 

When damaged by wind, schools typically experience the following types of building component damage in descending order 

of frequency of occurrence (see Figures 6-11 through 6-16):
6-18 MAKING SCHOOLS SAFE AGAINST WINDS 

Figure 6-11 

A portion of the built-up 

membrane at this school 

lifted and peeled after the 

metal edge flashing lifted. 

The cast-in-place concrete 

deck kept a lot of water 

from entering the school. 

Virtually all of the loose 

aggregate blew off the roof 

and broke many windows 

in nearby houses. This 

school was being used as a 

hurricane shelter at the time 

of the blow-off.

Figure 6-12 

The outer panes of these 

windows were broken by 

aggregate from a built-up 

roof. The inner panes had 

several impact craters. In 

several of the adjacent 

windows, both the outer and 

inner panes were broken. 

The aggregate had a flight 

path in excess of 245 feet. 

The wind speed was less 

than the design wind speed.

Roof covering damage (including rooftop mechanical, electrical, 

and communications equipment).

Exterior glazing damage – very common during hurricanes and 

tornadoes, less common during other storms.
MAKING SCHOOLS SAFE AGAINST WINDS 6-19

Figure 6-13 

The metal wall covering 

on this school was applied 

to plywood over metal 

studs. The metal stud wall 

collapsed in this area, but, 

in other areas, it was blown 

completely away. The CMU 

wall behind the studs did 

not appear to be damaged. 

This school was on the 

periphery of a violent 

tornado.

Figure 6-14 

The unreinforced CMU 

wall at this school 

collapsed during a storm 

that had wind speeds that 

were less than the design 

wind speed.

Exterior wall coverings and soffit damage.

Collapse of non-load bearing exterior walls.

SOURCE: OKLAHOMA AND 

KANSAS MIDWEST TORNADOES 

OF MAY 3, 1999, 1999
6-20 MAKING SCHOOLS SAFE AGAINST WINDS 

Figure 6-15 

The roof and all the 

walls of a wing of this 

elementary school were 

blown away by a violent 

tornado.

Structural damage (e.g., roof deck blow-off, blow-off or collapse 

of the roof structure, collapse of exterior bearing walls, or collapse 

of the entire school or major portions thereof). Structural damage, 

along with damage to the building envelope, is the number one 

type of damage during strong and violent tornadoes.

Figure 6-16 

This portable classroom 

was blown up against 

the main school building 

during a storm that had 

wind speeds that were 

less than the design wind 

speed. Depending upon 

the type of exterior wall, 

an impacting portable 

classroom may or may not 

cause wall collapse. 
MAKING SCHOOLS SAFE AGAINST WINDS 6-21

Ramifications of the above types of damages include: 

❍ Property damage. Including repair/replacement of the 

damaged components (or replacement of the entire facility), 

plus repair/replacement of interior building components, 

mold remediation, furniture, equipment, and books caused by 

water and/or wind entering the school. Even when damage to 

the building envelope is limited, such as blow-off of a portion of 

the roof covering or broken glazing, substantial water damage 

frequently occurs because heavy rains often accompany strong 

winds (particularly in the case of thunderstorms, hurricanes, 

and tornadoes; see Figure 6-17). 

Debris such as roof aggregate, gutters, HVAC equipment, 

and siding blown from schools can damage automobiles, 

residences, and other buildings in the vicinity of the school.

Debris can travel well in excess of 300 feet in wind events. If 

non-school property is damaged by school building debris, the 

school district will likely be responsible for the damage.

Portable classrooms are often particularly vulnerable to 

significant damage because they are seldom designed to the 

same wind loads as permanent school buildings. Portable

Figure 6-17 

This newly-constructed 

gymnasium had a structural 

metal roof panel (3-inch 

trapezoidal ribs at 24 

inches on center) applied 

over metal purlins. The 

panels detached from their 

concealed clips. A massive 

quantity of water entered 

the school and buckled the 

wood gym floor.
6-22 MAKING SCHOOLS SAFE AGAINST WINDS 

classrooms are frequently blown over 

during high-wind events because the 

inexpensive techniques that are typically 

used are inadequate to anchor the units 

to the ground. Wind-borne debris from 

portables or an entire portable classroom 

may impact the permanent school building 

and cause serious damage.

❍ Injury or death. Although infrequent, 

school occupants or people outside 

schools have been injured and killed when 

struck by collapsed building components 

(such as exterior masonry walls or the 

roof structure) or wind-borne building 

debris. The greatest risk of injury or death 

is during strong hurricanes and strong/

violent tornadoes. 

❍ Interrupted use. Depending upon the 

magnitude of wind and water damage, it 

can take days, months, or more than a year 

to repair the damage or replace a facility 

(see Figure 6-18). In addition to the costs 

associated with repairing/replacing the 

damage, other financial ramifications 

related to interrupted use of the school 

can include the cost of bussing students 

to an alternative school and/or rental of 

temporary facilities. These additional costs 

can be quite substantial. 

There are also social and psychological factors, 

such as difficulties imposed on students, parents, faculty and the administration during the 

time the school is not usable.

Although people are not usually 

outside a school during a high wind 

event, exceptions are schools used 

as hurricane shelters. In this case, it 

is common for people to arrive at a 

school during very high winds. Missiles 

such as roof aggregate shedding 

from the school could injure or kill 

late arrivers to the shelter. Another 

exception is the period of time when 

students are arriving at or departing 

from school. Thirteen students at the 

Belvidere High School in northern 

Illinois were killed and many others 

were seriously injured by a tornado 

in 1967. School had been dismissed 

shortly before the tornado struck and 

many students were in school buses as 

the tornado approached the school. An 

attempt was made to get the students 

back inside the school, but 12 of 

the buses were thrown about by the 

tornado before the students could seek 

shelter within the school. Aggregate 

from the school’s built-up roof 

penetrated the flesh of several students. 

Modest wind speeds can drive rain 

into the school’s exterior walls. Unless 

adequate provisions are taken to 

account for water infiltration (see 

Sections 6.10.4, 6.11.3, and 6.13.3), 

damaging corrosion, dry rot, and mold 

can occur within the walls.
MAKING SCHOOLS SAFE AGAINST WINDS 6-23

Figure 6-18 

A portion of the roof structure blew off of 

this school, and a portion of it collapsed into 

classrooms. Because of extensive water damage, 

a school such as this can be out of operation for a 

considerable period of time.

6.4 SCOPE, EFFECTIVENESS, AND 

LIMITATIONS OF BUILDING CODES

In the following section, the IBC is discussed. In some jurisdictions, NFPA 5000 or one of the earlier model building 

codes or a specially written state or local building code may be 

used. The specific scope and/or effectiveness and limitations 

of these other building codes will be somewhat different than 

that of the IBC. It is incumbent upon the architect/engineer 

to be aware of the specific code (including the edition of the 

code and local amendments) that has been adopted by the authority having jurisdiction. 
6-24 MAKING SCHOOLS SAFE AGAINST WINDS 

6.4.1 Scope

With respect to wind performance, the scopes of the model 

building codes have greatly expanded since the mid-1980s. Significant improvements include:

❍ Recognition of increased uplift loads at the roof perimeter 

and corners. Prior to the 1982 edition of the Standard 

Building Code and Uniform Building Code and the 1987 

edition of the National Building Code, these model codes 

did not account for the increased uplift at the roof perimeter 

and corners. Therefore, schools designed in accordance with 

earlier editions of these codes are very susceptible to blow-off 

of the roof deck and/or roof covering.

❍ Adoption of ASCE 7 for wind design loads. Although the 

three model codes permitted use of ASCE 7, the 2000 edition 

of the IBC was the first model code to require ASCE 7 for 

determining wind design loads. ASCE 7 has been more 

reflective of the current state of the knowledge than the 

model codes, and use of this procedure has typically resulted 

in higher design loads. 

❍ Roof coverings. Several performance and prescriptive 

requirements pertaining to wind resistance of roof coverings 

have been incorporated. The majority of these additional 

provisions were added after Hurricanes Hugo (1989) and 

Andrew (1992). Poor performance of roof coverings was 

widespread in both of those storms. Prior to the 1991 edition 

of the SBC and UBC and the 1990 edition of the NBC, these 

model codes were essentially silent on roof covering wind 

loads and test methods for determining uplift resistance. 

Code improvements continued to be made through the 2003 

edition of the IBC.

❍ Glazing protection. The 2000 edition of the IBC was the 

first model code to address wind-borne debris requirements 

for buildings located in the wind-borne debris regions of 

hurricane-prone regions (via reference to the 1998 edition of 
MAKING SCHOOLS SAFE AGAINST WINDS 6-25

ASCE 7). (The 1995 edition of ASCE 7 was the first edition to 

address wind-borne debris requirements).

❍ Parapets and rooftop equipment. The 2003 edition of 

the IBC was the first model code to address wind loads on 

parapets and rooftop equipment (via reference to the 2002 

edition of ASCE 7, which was the first edition of ASCE 7 to 

address these elements).

6.4.2 Effectiveness

Except for hurricanes and tornadoes, the 2003 edition of the IBC 

is believed to be a relatively effective code, provided that it is properly followed and enforced. This code is also believed to be an 

effective code for hurricanes, except that it does not account for 

water infiltration due to puncture of the roof membrane by missiles, nor does it adequately address the vulnerabilities of brittle 

roof coverings (such as tile) to missile-induced damage and subsequent progressive cascading failure.

The 2003 IBC relies on several referenced standards and test 

methods developed or updated in the 1990s. Most of these standards and test methods have not been validated by actual building 

performance during design level wind events. Therefore, the 

actual performance of buildings designed and constructed to the 

minimum provisions of the 2003 IBC remains to be determined. 

Future post-storm building performance evaluations may or may 

not show the need for further enhancements.

The 2003 IBC does not account for tornadoes; therefore, except 

for weak tornadoes, it is ineffective for this type of storm.

6.4.3 Limitations

Limitations to building codes include the following:

❍ Because codes are adopted on the local or state level, the 

adopting authority has the power to not adopt all wind-
6-26 MAKING SCHOOLS SAFE AGAINST WINDS 

related provisions of a model code, or to write their own code 

rather than follow a model code. In either case, important 

provisions of the current model code may be stricken, 

thereby resulting in schools that are more susceptible to 

wind damage when they are designed and constructed in 

accordance with the minimum requirements of the locally 

adopted code. Also, often there is a significant time lag 

between the time a model code is updated and the time it 

is implemented by the adopting authority. When lag occurs, 

schools designed to the minimum requirements of the 

outdated code are not taking advantage of the current state 

of the knowledge. Therefore, these schools are prone to 

poorer wind performance compared to schools designed 

according to the current model code.

❍ Adoption of the current model code does not ensure good 

wind performance. Rather, the code is a minimum tool 

that should be used by knowledgeable design professionals 

in conjunction with their training, skills, and professional 

judgment. To achieve good wind performance, in addition 

to good design, the construction work must be effectively 

executed and the school must be adequately maintained and 

repaired.

❍ Specific limitations of the 2003 IBC include lack of provisions 

pertaining to blow-off of aggregate from built-up and sprayed 

polyurethane foam roofs, and limitations of some of the test 

methods used to assess wind and wind-driven rain resistance 

of building envelope components (improved test methods 

need to be developed before this code limitation can be 

overcome). In addition, the code does not address protection 

of occupants in schools (and other buildings) located in 

tornado-prone regions.

❍ The 2003 IBC does not address the need for continuity, 

redundancy, or energy-dissipating capability (ductility) to 

limit the effects of local collapse and to prevent or minimize 

progressive collapse in the event of the loss of one or two 
MAKING SCHOOLS SAFE AGAINST WINDS 6-27

primary structural members such as a column. However, even 

though this issue is not addressed in the IBC, Chapter 1 of 

ASCE 7 does address general structural integrity, and the ASCE 

7 Chapter 1 Commentary provides some guidance on this issue. 

6.5 PRIORITIES, COSTS, AND BENEFITS: 

NEW SCHOOLS

Prior to evaluating schools for risk from high winds and beginning 

the risk reduction design process, it is first necessary to consider 

the priorities, costs, and benefits of potential risk reduction measures. These factors, as discussed below, should be considered 

within the context of performance-based wind design as discussed 

in Section 2.12.3.

6.5.1 Priorities

As previously discussed in this manual, the first priority is the implementation of measures that will reduce risk of casualties to students, 

faculty, staff, and visitors. The second priority is the reduction of 

damage that leads to downtime and disruption. The third priority 

is the reduction of damage and repair costs. To realize these priorities, as a minimum the school should be designed and constructed 

in accordance with the latest edition of a current model building 

code such as the IBC (unless the local building code has more conservative wind-related provisions, in which case the local building 

code should be used as the basis for design). In addition, the school 

should be adequately maintained and repaired.

For schools that will be used for emergency response after a storm 

and/or those schools that will be used for hurricane shelters, 

measures beyond those required by the IBC should be given high 

priority (see Section 6.15).

For schools in coastal Alaska and other areas that experience 

frequent high-wind events (such as parts of Colorado), measures 

beyond those required by the IBC should be given high priority. 

Several of the recommendations for schools in hurricane-prone 
6-28 MAKING SCHOOLS SAFE AGAINST WINDS 

regions (Section 6.15) are also applicable to these schools, with 

the exception of the wind-borne debris recommendations. (Limited amounts of wind-borne debris are generated in storms other 

than hurricanes and tornadoes.)

For schools located in tornado-prone regions, priority should be 

given to the incorporation of specially designed occupant shelters 

within the school (see Section 6.16). The decision to incorporate 

occupant shelters should be based on the assessment of risk (see 

Section 6.7.1). 

For schools located in areas where the basic wind speed is greater 

than 90 mph, priority should be given to incorporation of design, 

construction, and maintenance enhancements. The degree of priority given to these enhancements increases as the 

basic wind speed increases (see Sections 6.8.3 to 

6.8.5 and 6.9 to 6.14 for enhancement examples).

6.5.2 Cost, Budgeting, and 

Benefits

The cost for complying with the IBC should be 

considered as the minimum baseline cost. 

For schools that will be used for emergency response after a storm and/or those schools that 

will be used for hurricane shelters, the additional 

cost for implementing measures beyond those 

required by the 2003 edition of the IBC will typically add only a small percentage to the total cost 

of construction. Sections 6.8 and 6.15 discuss additional measures that should be considered. 

For all other schools other than those discussed 

above, the additional cost for implementing enThe benefit/cost ratio of incorporating 

specially designed tornado shelters 

within schools can be assessed using 

software that accompanies FEMA 361.4

Tornado shelters have been constructed 

in several schools in Kansas and 

Oklahoma. An architect involved with 

several of the Kansas schools reports 

that the additional cost to incorporate 

a shelter ranges from $30 to $38 per 

square foot of shelter space (year 2002 

costs). FEMA 361 recommends using a 

minimum of 5 square feet per person for 

sheltering; therefore, the $30 to $38 psf 

equates to $150 to $190 per student 

and staff for “near absolute protection” 

(i.e., protection from injury or death) 

from a violent tornado. Tornado shelters 

are discussed in Section 6.16.

4 FEMA 361, Design and Construction Guidance for Community Shelters, 2000, is a manual for 

architects and engineers. It presents detailed guidance concerning the design and construction 

of shelters that provide “near-absolute protection” from tornadoes. FEMA 361 discusses shelter 

location, design loads for wind pressure and wind-borne debris, performance criteria, and human 

factor criteria. It is accompanied by a benefit/cost analysis model.
MAKING SCHOOLS SAFE AGAINST WINDS 6-29

hancements will typically add only a very small percentage to the 

total cost of construction. Sections 6.8 to 6.14 discuss additional 

measures that should be considered.

The yearly cost of periodic maintenance and repair will be 

greater than the alternative of not expending any funds for periodic maintenance (i.e., deferred maintenance and repair). If, 

however, the deferred maintenance option is selected, eventually 

maintenance and repairs will be required, and the extent and 

cost of the work will typically be much greater than the costs associated with the periodic option. Also, if a windstorm causes 

damage that would have otherwise been avoided had maintenance or repairs been performed, the resulting costs can be 

significantly higher. (Note: Maintenance and repair costs are 

reduced when more durable materials and systems are used; see 

Section 6.8.2, under “Step 4: Durability.”)

Budgeting. It is important for the school district to give consideration to wind enhancement costs early in the development of 

a new school project. If enhancements, particularly those associated with schools used as hurricane shelters, emergency response 

after a storm, and tornado shelters, are not included in the initial 

project budget, often it is very difficult to find funds later during 

the design of the project. If the additional funds are not found, 

the enhancements may be eliminated because of lack of forethought and adequate budgeting. 

Benefits. If strong storms do not occur during the life of a school, 

there is little benefit to spending the money and effort related 

to wind resistance. However, considering the long life of most 

schools (hence, the greater probability of them experiencing a 

design level event) and considering the importance placed on 

students and the value of the school to the community, clearly 

it is prudent to invest in adequate wind resistance. By doing so, 

the potential for loss of life and injuries can be significantly reduced or virtually eliminated. Investing in wind resistance also 

minimizes future expenditures for repair or replacement of winddamaged schools and avoids costly interrupted building use.
6-30 MAKING SCHOOLS SAFE AGAINST WINDS 

Fortunately, most of the enhancements pertaining to increased 

wind resistance are relatively inexpensive compared to the benefit 

that they provide. In evaluating what enhancements are prudent 

for a specific school, an enhancement that provides greater performance reliability at little cost is an enhancement worthy of 

consideration (see Figure 6-19).

Wind resistance enhancements may also result in decreased insurance premiums. The school district’s insurer should be consulted 

to see if premium reductions are available, and to see if special 

enhancements are required in order to avoid paying a premium 

for insurance. For those school districts that self-insure, enhanced 

wind resistance should result in a reduction of future payouts.

6.6 PRIORITIES, COSTS, AND BENEFITS: 

EXISTING SCHOOLS

Prior to evaluating existing schools for risk from high winds and 

beginning the risk reduction design process, it is first necessary 

to consider the priorities, costs, and benefits of potential risk reduction measures. These factors, as discussed below, should be 

considered within the context of performance-based wind design 

as discussed in Section 2.12.3. 

Figure 6-19 

The HVAC unit in the 

parking lot in the photo’s 

lower right corner blew 

off the curb during a storm 

that had wind speeds that 

were less than the design 

wind speed. A substantial 

amount of water entered 

the building before a 

temporary covering 

could be placed over the 

opening. The blow-off 

was caused by a load 

path discontinuity; no 

provisions had been made 

to anchor the unit to the 

curb. The insignificant cost 

of a few fasteners would 

have prevented repairs 

costing several thousand 

dollars and also prevented 

interrupted use of a portion 

of the building.
MAKING SCHOOLS SAFE AGAINST WINDS 6-31

6.6.1 Priorities

In prioritizing work at existing schools, an assessment should 

be made on all schools within the district to ascertain which 

schools are vulnerable to damage and therefore most in need 

of remedial work. As part of the assessment, the nature of the 

vulnerability and the needed remedial work should be identified 

at the various schools. In making the district-wide assessment, all 

applicable hazards should be assessed and the needs prioritized. 

For some districts or some schools within a given district, the 

high priority work may be related to wind, or it may be related to 

one of the other hazards. In some instances, the same remedial 

work item can mitigate wind and other hazards. For example, 

strengthening the roof deck attachment can improve both wind 

and seismic resistance.

School districts located in following areas are in greatest need of 

assessing their schools (listed in descending order of priority): 

hurricane-prone regions and school districts outside of hurricaneprone regions that have schools that will be used for emergency 

response after a storm; tornado-prone regions; areas where the 

basic wind speed is in excess of 90 mph (the priority increases as 

the basic wind speed increases); and areas where the basic wind 

speed is 90 mph or less.

For school districts in hurricane-prone regions, the first priority 

needs to be given to those schools that will be used as hurricane 

shelters. Other priorities are as discussed at the beginning of 

Section 6.5.1.

For school districts in tornado-prone regions, the first priority 

needs to be given to occupant protection (see Section 6.16). 

Other priorities are the same as discussed at the beginning of 

Section 6.5.1.

For all other school districts, the priorities are the same as discussed at the beginning of Section 6.5.1.
6-32 MAKING SCHOOLS SAFE AGAINST WINDS 

In some instances, perhaps all the funds available for the year for 

remedial work will be spent at one school. In other instances, perhaps the available funds will be used for remedial work at several 

different schools.

See Section 6.17 for specific remedial work guidance.

6.6.2 Cost, Budgeting, and Benefits

Wind-resistance improvements would ideally address all elements 

in the load path from the building envelope to the structural 

system and into the ground. (Load path is discussed in Section 

6.8.2 under “Step 3: Detailed Design”); however, this approach 

can be very expensive if there are many inadequacies throughout 

the load path. The maximum return on dollars invested for windresistance improvements is typically achieved by performing work 

related to the building envelope. Obviously if there are serious 

structural deficiencies that could lead to collapse during strong 

storms, these types of deficiencies should receive top priority; however, this scenario is infrequent. 

Because elements of the building envelope are the building 

components that are most likely to fail in the more commonly 

occurring moderate wind speed events, strengthening these elements will avoid damage during those storms. Of course, if a 

storm approaching a design level event occurs, in this scenario, 

the building envelope will remain attached to the structure, but 

a structural element may fail. For example, if the connections 

between the roof joists and bearing walls are the weak link, the 

roof covering will remain attached to the roof deck and the deck 

will remain attached to the joists, but the entire roof structure will 

blow off because the joists will detach from the wall. Although loss 

of the entire roof structure is more catastrophic than the loss of 

just the roof covering, much stronger events are typically required 

to cause structural damage. Hence, on a school district-wide level, 

strengthening building envelopes can result in maximum return 

on funds spent on wind-resistance improvements. Of course, for 

a specific school, the actual scope of wind-resistance work should 
MAKING SCHOOLS SAFE AGAINST WINDS 6-33

be tailored for that school, commensurate with the findings from 

the evaluation (as discussed in Section 6.6.1) and the benefit/cost 

analysis (as discussed in below under “Benefits”).

Costs can be minimized if wind-resistance improvements are executed as part of planned repairs or replacement. For example, 

if the roof deck is inadequately attached in the perimeter and 

corners, and the roof covering has another 10 years of remaining 

service life, it would typically be prudent to hold off performing 

deck attachment upgrade until it is necessary to replace the roof 

covering. Then, as part of the reroofing work, the existing roof 

system could be torn off, the deck reattached, and the new membrane installed.5

 With this approach, the full service life of the 

roof membrane (and, hence, its full economic value) is achieved.

Budgeting. As it is with new construction, it is important for the 

school district to give consideration to wind enhancement costs 

early in the development of a major repair/renovation project 

(see discussion in Section 6.5.2).

Benefits. The benefits for spending money and effort related to 

wind resistance of existing schools are the same as described for 

new schools in Section 6.5.2.

6.7 EVALUATING SCHOOLS FOR RISK FROM 

HIGH WINDS

To evaluate risk for wind storms other than tornadoes, the following steps are recommended:

❍ Step 1: Determine the basic wind speed from ASCE 7. As 

the basic wind speed increases beyond 90 mph, the risk of 

damage increases and it continues to increase as the speed 

increases. To compensate for the increased risk of damage, 

design, construction and maintenance enhancements are 

recommended (see Section 6.8). 

5 In some cases, it is economical to reattach the decking from below the deck, but typically this 

approach is more costly.
6-34 MAKING SCHOOLS SAFE AGAINST WINDS 

❍ Step 2: For schools not located in hurricaneprone regions, determine if the school 

will be used for emergency response after 

a storm (e.g., temporary housing, food 

or clothing distribution, or a place where 

people can fill out forms for assistance). If 

so, refer to the design, construction, and 

maintenance enhancements recommended 

for schools in hurricane-prone regions (see 

Section 6.15).

❍ Step 3: For schools in hurricane-prone regions, determine if the school will be used 

for a hurricane shelter and/or for emergency response after a storm. If so, refer to the 

design, construction, and maintenance enhancements recommended in Section 6.15. 

❍ Step 4: For existing schools, evaluate the wind resistance of 

the building. The resistance will be a function of its original 

design and construction, various additions or modifications, 

and condition of building components (which may have 

weakened due to deterioration or fatigue).

As a first step, calculate the wind loads on the school using 

ASCE 7 and compare these loads with the loads that the 

school was originally designed for. (The original design 

loads may be noted on the contract drawings. If not, 

determine what building code or standard was used to 

develop the original design loads and calculate the loads 

using that code or standard.) If the original design loads are 

significantly lower than current loads, upgrading the load 

resistance of the building envelope and/or structure should 

be considered (see Section 6.6.2). (Note: An alternative 

to comparing current loads with original design loads is to 

evaluate the resistance of the existing school as a function 

of the current loads to determine what elements are highly 

overstressed.)

As part of Steps 2 and 3, consider 

availability of other schools or other 

buildings in the community that could 

be used for educational purposes (and 

emergency response if the school is 

so designated) in the event that the 

school is damaged. For example, in 

an isolated community, the school 

may be the only facility available for 

education and/or emergency response, 

in which case loss of school use would 

be very serious. In this scenario, the 

enhancements given in Section 6.15 

should be even more robust.
MAKING SCHOOLS SAFE AGAINST WINDS 6-35

As a second step, perform a field investigation to evaluate the 

primary building envelope elements and structural system 

elements to determine if the school was generally constructed 

as indicated on the original contract drawings. As part of the 

investigation, the primary elements should be checked for 

deterioration. Load path continuity should also be checked.

The above evaluations will allow development of a 

vulnerability assessment that can be used along with the 

site’s wind regime to assess the risk. See Section 6.17 for 

remedial work recommendations.

6.7.1 Tornadoes 

Neither the IBC or ASCE 7 require buildings (including 

schools) to be designed for tornadoes, nor are occupant 

shelters required in buildings (including schools) located in 

tornado-prone regions. Because of the extremely high pressures 

and missile loads that tornadoes can induce, constructing tornado-resistant schools is extremely expensive. Therefore, when 

consideration is voluntarily given to tornado design, the emphasis typically is on occupant protection, which is achieved by 

“hardening” portions of a school for use as safe havens.

In this manual, the term “tornado-prone regions” refers to those 

areas of the U.S. where the number of recorded F3, F4, and F5 

tornadoes per 3,700 square miles is six or greater (see Figure 6-

2). However, a school district may decide to use other frequency 

values (e.g., 1 or greater, 16 or greater, or greater than 25) in 

defining whether or not the district is in a tornado-prone area. 

In this manual, tornado shelters are recommended for schools 

in tornado-prone regions. 

FEMA 361, Design and Construction Guidance for Community 

Shelters, includes a comprehensive risk assessment procedure 

that designers can use to assist school districts in determining 

whether a tornado shelter should be included as part of a new 

school. See Section 6.16 for design of tornado shelters.
6-36 MAKING SCHOOLS SAFE AGAINST WINDS 

Where the number of recorded F3, F4, and F5 tornadoes per 

3,700 square miles is one or greater, if the school does not have a 

tornado shelter, the best available refuge areas should be identified as discussed in Section 6.16.

6.7.2 Portable Classrooms 

Unless portables are designed and constructed (including anchorage to the ground) to meet the same wind loads as the 

main school building, students and faculty should be considered 

at risk during high winds. Therefore, portables should not be 

occupied when high winds are forecast (even though the forecast speeds are well below design wind conditions for the main 

building). Also, during winds that are well below design wind 

conditions, it should be recognized that wind-borne debris from 

disintegrating portables could impact and damage the main 

school building and/or nearby residences.

6.8 RISK REDUCTION DESIGN METHODS 

The keys to enhanced wind performance are devoting sufficient attention to design, construction contract administration, 

construction, maintenance, and repair. Of course, it is first necessary for the school district to budget sufficient funds for this 

effort (see Sections 6.5.2 and 6.6.2). This section provides an 

overview of these elements:

6.8.1 Siting

Where possible, a school should not be located in Exposure D. 

Locating the facility on a site in Exposure C or preferably in Exposure B would decrease the wind loads. Also, where possible, 

avoid locating a school on an escarpment or upper half of a hill. 

Otherwise, if the school is located on an escarpment or upper half 

of a hill, the abrupt change in the topography would result in increased wind loads. When siting on an escarpment or upper half 

of a hill is necessary, the ASCE 7 design procedure accounts for 

wind speed-up associated with this abrupt change in topography.
MAKING SCHOOLS SAFE AGAINST WINDS 6-37

Trees in excess of 6 inches in diameter, poles (e.g., light fixture 

poles, flag poles, power poles), or towers (e.g., electrical transmission and communication towers) should not be placed near 

the school. Blow-down of large trees, poles, and towers can severely damage a school and injure occupants.

Providing at least two means of site egress is prudent for all 

schools, but is particularly important for schools used for hurricane shelters and emergency response after a storm. Two 

means of egress facilitate emergency vehicles that need to reach 

or leave the site. With multiple site egress roads, if one route 

becomes blocked by trees or other debris or by floodwaters, another access route should be available.

To the extent possible, site portable classrooms so that, if they disintegrate during a storm that approaches from the prevailing wind 

direction, debris will avoid impacting the main school building 

and residences. Debris can travel in excess of 300 feet. Destructive 

winds from hurricanes and tornadoes can approach from any direction. These storms can also throw debris much farther.

6.8.2 School Design 

Good wind performance depends on good design (including detailing and specifying), materials, application, maintenance, and 

repair. A significant shortcoming of any of these five elements 

could jeopardize the performance of a school against wind. Design, however, is the key element to achieving good performance 

of a school against wind. Design inadequacies frequently cannot 

be compensated for by the other four elements. Good design, 

however, can compensate for other inadequacies to some extent.

Step 1: Calculate Loads

Calculate loads on the main wind-force resisting system 

(MWFRS; i.e., the primary structural elements such as beams, 

columns, shear walls, and diaphragms that provide support and 

stability for the overall building), the building envelope, and 
6-38 MAKING SCHOOLS SAFE AGAINST WINDS 

rooftop equipment in accordance with ASCE 7 

or the local building code, whichever procedure 

results in the highest loads.6 The importance 

factor for most schools will be required to be 

1.15. For schools with an occupant load of 250 

or less and not intended for use as shelters, a 

1.00 importance factor is permitted; however, a 

value of 1.15 is recommended for all schools. 

Uplift loads on roof assemblies can also be determined from Factory Mutual Global (FMG) 

Data Sheets. In some instances, the loads derived from ASCE 7 or the local code may exceed 

those derived from FMG, but, in other cases, the 

FMG loads may be higher. If the school is FMGinsured, and the FMG-derived loads are higher 

than those derived from ASCE 7 or the building 

code, the FMG loads should govern; however, 

if the ASCE 7 or code-derived loads are higher 

than those from FMG, the ASCE 7 or code-derived loads should govern (whichever procedure results in the 

highest loads). 

Step 2: Determine Load Resistance 

After loads have been determined, it is necessary to determine 

a reasonable safety factor (when using allowable stress design) 

or reasonable load factor (when using strength design). For 

building envelope systems, a minimum safety factor of two is 

recommended; for anchorage of exterior-mounted mechanical, 

electrical and communications equipment (such as satellite 

dishes), a minimum safety factor of three is recommended. 

For structural members and many cladding elements, load resistance can be determined by calculations, based on test data. For 

other elements (such as most types of roof coverings), load resistance is primarily obtained from system testing.

6 Criteria for determining loads on rooftop equipment were added to the 2002 edition of ASCE 7.

In the past, architects seldom performed 

load calculations on the building 

envelope (i.e., roof and wall coverings, 

doors, windows, and skylights) and 

rooftop equipment and neither did 

structural engineers. In large part, as 

a result of not determining loads on 

these elements and not designing them 

with adequate load resistance, building 

envelope and rooftop equipment 

failures have been the leading cause of 

failure during past wind events. Just as it 

is with the MWFRS, it is imperative that 

loads be determined by the architect or 

engineer for the building envelope and 

rooftop equipment, and the envelope 

and rooftop equipment designed to 

accommodate the design loads.
MAKING SCHOOLS SAFE AGAINST WINDS 6-39

Load resistance criteria need to be given in contract documents. For structural elements, the designer of record typically 

accounts for load resistance by indicating the material, size, 

spacing, and connection of elements. For nonstructural elements, such as roof coverings or windows, the load and safety 

factor can be specified. In this case, the specifications should 

require the contractor’s submittals to show that the system will 

meet the load resistance criteria. This performance specification 

approach is necessary if, at the time of design, it is unknown 

who will manufacture the system.

Regardless of which approach is used, it is important that 

the designer of record ensure that it can be demonstrated 

that the structure, nonstructural building envelope, and exterior-mounted mechanical, electrical, and communications 

equipment have sufficient strength to resist design wind loads.

Step 3: Detailed Design

Design, detail, and specify the structural system, 

building envelope, and exterior-mounted 

mechanical, electrical, and communications 

equipment to meet the factored design loads 

(based on appropriate analytical or test methods) 

and as appropriate to respond to the risk 

assessment discussed in Section 6.7.

As part of the detailed design effort, load 

path continuity should be clearly indicated 

in the contract documents. Load paths need 

to accommodate design uplift, racking, and 

overturning loads. Load path continuity 

obviously applies to MWFRS elements, but it also 

applies to building envelope elements. Figure 

6-19 shows a load path discontinuity between a piece of HVAC 

equipment and its equipment curb. Figure 6-20 illustrates the 

load path concept. 

Connections: Connections are a key 

aspect of load path continuity between 

various structural and nonstructural 

building elements. For example, 

consider a window: the glass must be 

strong enough to resist the applied 

load and the glass must be adequately 

anchored to the window frame, the 

frame adequately anchored to the 

wall, the wall adequately anchored 

to the foundation, and the foundation 

adequately anchored to the ground. As 

loads increase, greater load capacity 

must be developed in the connections. 
6-40 MAKING SCHOOLS SAFE AGAINST WINDS 

Figure 6-20 

This figure illustrates load 

path continuity of the 

structural system. Members 

are sized to accommodate 

the design loads and 

connections are designed 

to transfer uplift loads 

applied to the roof, and the 

positive and negative loads 

applied to the exterior 

bearing walls down to the 

foundation and into the 

ground. The roof covering 

(and wall covering if 

there is one) is also part 

of the load path. To avoid 

blow-off, the nonstructural 

elements must also be 

adequately attached to the 

structure. 

SOURCE: FEMA 342, OKLAHOMA 

AND KANSAS MIDWEST 

TORNADOES OF MAY 3, 1999, 

1999

Step 4: Durability

Because some locales have very aggressive atmospheric corrosion 

(such as schools located near oceans), special attention needs 

to be given to specification of adequate protection for ferrous 

metals, or specify alternative metals such as stainless steel. Corrosion Protection for Metal Connectors in Coastal Areas, FEMA Technical 

Bulletin 8-96, August 1996, contains information on corrosion 

protection. Attention also needs to be given to dry rot avoidance, 
MAKING SCHOOLS SAFE AGAINST WINDS 6-41

for example, by specifying preservative-treated wood. Appendix J 

of the Coastal Construction Manual, FEMA 55, Third Edition, 2000, 

presents information on wood durability.

Durable materials are particularly important for components that 

are concealed, which thereby prohibit knowing that the component is in imminent danger of failing. 

Special attention also needs to be given to details. For example, 

details that do not allow water to stand at connections or sills are preferred. Without special attention to material selection and details, 

the demands on maintenance and repair will be increased, along 

with the likelihood of failure of components during high winds.

Step 5: Rain Penetration

Although prevention of building collapse and major building 

damage is the primary goal of wind-resistant design, consideration should also be given to minimizing water damage and 

subsequent development of mold from penetration of winddriven rain. To the extent possible, non-load bearing walls and 

door and window frames should be designed in accordance with 

rain-screen principles. With this approach, it is assumed that 

some water infiltration will occur. The water is intercepted in 

an air-pressure equalized cavity that provides drainage from the 

cavity to the outer surface of the building. See Sections 6.11.3 

and 6.13.3, and Figure 6-47 for further discussion and an example. Further information on the rain-screen principle can be 

found in Facts and Fictions of Rain-Screen Walls, M.Z. Rousseau, 

Construction Canada, 1990. 

In conjunction with the rain-screen principle, it is desirable 

to avoid using sealant as the first line of defense against water 

infiltration. When joints are exposed, obtaining long-lasting watertight performance is difficult because of the complexities of 

sealant joint design and application.
6-42 MAKING SCHOOLS SAFE AGAINST WINDS 

6.8.3 Peer Review

If the design team’s wind design expertise and experience is limited, 

wind design input and/or peer review should be sought from a qualified individual(s). The design input or peer review could be for the 

entire school or for specific components such as the roof or glazing 

systems that are critical and/or beyond the design team’s expertise. 

Regardless of the design team’s expertise and experience, peer review should be considered when the school:

❍ is located in an area where the basic wind speed is greater 

than 90 mph (peak gust)

❍ will be used for emergency response after a storm

❍ will be used for a hurricane shelter

❍ will incorporate a tornado shelter

6.8.4 Construction Contract Administration

After a suitable design is complete, the design team should ensure the design intent is achieved during construction. The key 

elements of construction contract administration are submittal 

reviews and field observations, as discussed below.

Submittals. The specifications need to stipulate the submittal 

requirements. This includes specifying what systems require 

submittals (e.g., windows) and test data (where appropriate). 

Each submittal should demonstrate development of a load 

path through the system and into its supporting element. For 

example, a window submittal should show that the glazing has 

sufficient strength, its attachment to the frame is adequate, and 

the attachment of the frame to the wall is adequate.

During submittal review, it is important for the designer of record to be diligent in ensuring that all required submittals are 

submitted and that they include the necessary information. The 

submittal information needs to be thoroughly checked to ensure 
MAKING SCHOOLS SAFE AGAINST WINDS 6-43

its validity. For example, if a test method used to demonstrate 

compliance with the design load appears erroneous, the test data 

should be rejected unless the contractor can demonstrate the 

test method was suitable.

Field Observations. It is recommended that the design team 

analyze the design to determine which elements are critical 

to ensuring high-wind performance. The analysis should include the structural system and exterior-mounted electrical 

equipment, but it should focus on the building envelope and 

exterior-mounted mechanical and communications equipment. 

After determining the list of critical elements to be observed, 

observation frequency needs to be determined. Observation frequency will depend on the magnitude of the results of the risk 

assessment described in Section 6.7, complexity of the facility, 

and the competency of the general contractor, subcontractors, 

and suppliers.

See Section 6.15.8 for schools located in hurricane-prone regions.

6.8.5 Post-occupancy Inspections, Periodic 

Maintenance, Repair, and Replacement

The design team should advise the school administration of the 

importance of periodic inspections, maintenance, and timely 

repair. It is important for the administration to understand that, 

over time, a facility’s wind-resistance will degrade due to exposure to weather unless it is periodically maintained and repaired. 

The building envelope and exterior-mounted equipment should 

be inspected once a year by persons knowledgeable of the 

systems/materials they are inspecting. Items that require maintenance, repair, or replacement should be documented and 

scheduled for work. [Note: The deterioration of glazing is often 

overlooked. After several years of exposure, scratches and chips 

can become extensive enough to weaken the glazing.]
6-44 MAKING SCHOOLS SAFE AGAINST WINDS 

The goal is to repair or replace items before they fail in a storm. 

This approach is less expensive than waiting for failure and then 

repairing the failed components and consequential damages.

If unusually high winds occur, a special inspection is recommended. The purpose of the inspection is to assess if the strong 

storm caused damage that needs to be repaired to maintain 

building strength and integrity. In addition to inspecting for obvious signs of damage, the inspector should determine if cracks or 

other openings have developed that allow water infiltration, which 

could lead to corrosion or dry rot of concealed components.

See Section 6.15.9 for schools located in hurricane-prone regions.

6.9 STRUCTURAL SYSTEMS

Based on post-storm damage evaluations, with the exception of 

tornado events, the structural systems (i.e., MWFRS and structural components such as roof decking) of school buildings 

have typically performed quite well during design wind events. 

There have, however, been notable exceptions; in these cases, 

the most common problem has been blow-off of the roof deck, 

but instances of collapse have also been documented (Figure 6-

15). The structural problems have primarily been due to lack of 

an adequate load path, with connection failure being a common 

occurrence. Problems have also been caused by reduced structural capacity due to termites, workmanship errors (commonly 

associated with steel decks attached by puddle welds), and limited uplift resistance of deck connections in roof perimeters and 

corners (due to lack of code-required enhancement in older editions of the model codes).

With the exception of tornado events, structural systems designed and constructed in accordance with the IBC should 

typically offer adequate wind resistance, provided attention is 

given to load path continuity and to material durability (with 

respect to corrosion and termites). However, the greatest reliability is offered by cast-in-place concrete. There are no reports 
MAKING SCHOOLS SAFE AGAINST WINDS 6-45

of any cast-in-place concrete buildings experiencing a significant 

structural problem during wind events, including the strongest 

hurricanes (Category V) and tornadoes (F5). 

The following design parameters are recommended (see Section 

6.15.2 for schools located in hurricane-prone regions):

❍ If a pre-engineered structure is being contemplated, special 

steps should be taken to ensure the structure has more 

redundancy than is typically the case with pre-engineered 

buildings.7 Steps should be taken to ensure the structure is 

not vulnerable to progressive collapse in the event a primary 

bent is compromised or bracing components fail.

❍ Exterior load bearing walls of masonry or precast concrete 

should be designed to have sufficient strength to resist 

external and internal loading of components and cladding. 

CMU walls should have vertical and horizontal reinforcing 

and grout to resist wind loads. The connections of precast 

concrete wall panels should be designed to have sufficient 

strength to resist wind loads.

❍ For roof decks, specify concrete, steel, or wood sheathing 

(plywood or oriented strand board [OSB]). See Section 6.15.2 

for schools located in hurricane-prone regions.

❍ For steel roof decks, specify screw attachment rather than 

puddle welds (screws are more reliable and much less 

susceptible to workmanship problems). See Figures 6-21 

and 6-22. The decking shown in Figure 6-21 was attached 

with puddle welds. However, at most of the welds, there was 

only superficial bonding of the metal deck to the joist, as 

illustrated at this weld. Only a small portion of the deck near 

the center of the weld area (as delineated by the circle) was 

well fused to the joist. At the weld, shown in Figure 6-22, the 

deck was well bonded to the joist. When the decking blew off 

7 Pre-engineered structures are composed of rigid steel frames, secondary members (including roof 

purlins and wall girts made of Z- or C-shaped members) and bracing. 
6-46 MAKING SCHOOLS SAFE AGAINST WINDS 

Figure 6-21 

View of a steel joist after the 

metal decking blew away

Figure 6-22 

View of another weld near 

the weld shown in Figure 

6-21 

due to failure of nearby weak welds, at this location the metal 

decking tore and a portion of it remained attached to the 

joist. Tearing of the decking, rather than debonding, is the 

desired failure mode, but deck tearing is rare due to welding 

reliability problems. Screw attachment is a more reliable 

attachment method.
MAKING SCHOOLS SAFE AGAINST WINDS 6-47

Figure 6-23 

Portions of this waffled 

precast concrete roof deck 

were blown off. Bolts had 

been installed to provide 

uplift resistance; however, 

anchor plates and nuts had 

not been installed. Without 

the anchor plates, the 

dead load of the deck was 

inadequate to resist the 

wind uplift load.

Figure 6-24 

Several of the precast twinTee roof and wall panels 

collapsed. The connection 

between the roof and wall 

panels provided very little 

uplift load resistance. This 

roof panel lifted because 

of combined effects of 

wind uplift and pretension.

❍ For attachment of wood sheathed roof decks, specify screws, 

or ring-shank or screw-shank nails in the corner regions of the 

roof. Where the basic wind speed is greater than 90 mph, also 

specify these types of fasteners for the perimeter regions of 

the roof.

❍ For precast concrete decks, design the deck connections to 

resist the design uplift loads (the dead load of the deck itself 

is often inadequate to resist the uplift load; see Figure 6-23).
6-48 MAKING SCHOOLS SAFE AGAINST WINDS 

❍ For precast Tee decks, design the reinforcing to accommodate 

the uplift loads in addition to the gravity loads. Otherwise, 

large uplift forces can cause Tee failure due to the Tee’s own 

prestress forces after the uplift load exceeds the dead load of 

the Tee (see Figure 6-24).

❍ For schools that have mechanically attached single-ply or modified bitumen membranes, refer to the decking recommendations presented in the National Research Council of Canada, 

Institute for Research in Construction, Wind Design Guide for 

Mechanically Attached Flexible Membrane Roofs, B1049, 2004.

❍ If an FMG-rated roof assembly is specified, the roof deck also 

needs to comply with the FMG criteria.

6.10 EXTERIOR DOORS

This section addresses primary and secondary egress doors, sectional (garage) doors, and rolling doors. See Section 6.15.3 for 

schools located in hurricane-prone regions.

6.10.1 Loads and Resistance

The IBC requires that the door assembly (i.e., door, hardware, 

frame, and frame attachment to the wall) be of sufficient strength 

to resist the positive and negative design wind pressure. Architects should specify that doors comply with wind load testing in 

accordance with ASTM E 1233. Architects should also specifically 

design the attachment of the door frame to the wall (e.g., specify 

the type, size, and spacing of frame fasteners).

See Section 6.15.3 for schools located in hurricane-prone regions.

6.10.2 Durability

Where corrosion is problematic, anodized aluminum or galvanized doors and frames, and stainless steel frame anchors and 

hardware are recommended. 
MAKING SCHOOLS SAFE AGAINST WINDS 6-49

6.10.3 Exit Door Hardware

For primary swinging entry/exit doors, exit door hardware is recommended to minimize the possibility of the doors being pulled 

open by wind suction. Exit hardware with top and bottom rods offers greater securement than exit hardware that latches at the jamb.

6.10.4 Water Infiltration

When heavy rain accompanies high winds (e.g., thunderstorms, 

tropical storms, and hurricanes), it can cause wind-driven water 

infiltration problems (the magnitude of the problem increases 

with the wind speed). Leakage can occur between the door and 

frame, and frame and wall, and water can be driven between the 

threshold and door. When the basic wind speed is greater than 

120 mph, because of the very high design wind pressures and 

numerous opportunities for leakage path development, some 

leakage should be anticipated when design wind speed conditions are approached. To minimize infiltration, the following 

are recommended:

❍ Vestibule. Designing a vestibule is a method to account for the 

infiltration problem. With this approach, both the inner and 

outer doors can be equipped with weatherstripping, and the 

vestibule itself can be designed to tolerate water. For example, 

water-resistant finishes (e.g., concrete or tile) can be specified 

and the floor can be equipped with a drain.

❍ Door swing. With respect to weatherstripping, out-swinging 

doors offer an advantage compared to in-swinging doors. 

With out-swinging doors, the weatherstripping is located 

on the interior side of the door, where it is less susceptible 

to degradation. Also, some interlocking weatherstripping 

assemblies are available for out-swinging doors. 

Another challenge with doors is successful integration between 

the door frame and wall. See Section 6.13.3 for discussion of this 

juncture. 
6-50 MAKING SCHOOLS SAFE AGAINST WINDS 

ASTM E 2112 (Standard Practice for Installation of Exterior Windows, 

Doors and Skylights) provides information pertaining to installation of doors, including the use of sill pan flashings with end 

dams and rear legs (see Figure 6-25). It is recommended that designers use E 2112 as a design resource.

Figure 6-25 

Door sill pan flashing with 

end dams, rear leg, and 

turned-down front leg

Figure 6-26 

Drip at door head and drip 

with hook at head

SOURCE: FEMA 55, COASTAL 

CONSTRUCTION MANUAL, 2000

6.10.5 Weatherstripping

A variety of pre-manufactured weatherstripping components are 

available, including drips, door shoes and bottoms, thresholds, 

and jamb/head weatherstripping. A few examples of weatherstripping options are:

❍ Drip. These are intended to shed water away from the 

opening between the frame and door head, and the opening 

between the door bottom and the threshold (see Figures 

6-26 and 6-27). Alternatively, a door sweep can be specified 

(see Figure 6-28); however, for high-traffic doors, periodic 

replacement of the neoprene will be necessary.
MAKING SCHOOLS SAFE AGAINST WINDS 6-51

❍ Door shoes and bottoms.

These are intended to 

minimize the gap between 

the door and threshold. 

Figure 6-27 illustrates a door 

shoe that incorporates a 

drip. Figure 6-29 illustrates 

an automatic door bottom. 

Door bottoms can be 

surface-mounted or 

mortised. For high-traffic 

doors, periodic replacement 

of the neoprene will be 

necessary.

❍ Thresholds. These are 

available to suit a variety 

of conditions. Thresholds with vertical offsets offer enhanced 

resistance to wind-driven water infiltration. However, where 

Americans with Disabilities Act (ADA)-compliant thresholds 

are required, or at high-traffic doors, the offset is limited. 

However, at other doors, high offsets are preferred.

Figure 6-28 

Neoprene door bottom sweep

Figure 6-27 

Door shoe with drip and vinyl seal 

Figure 6-29 

Automatic door bottom

SOURCE: FEMA 55, COASTAL 

CONSTRUCTION MANUAL, 2000

SOURCE: FEMA 55, COASTAL 

CONSTRUCTION MANUAL, 2000

SOURCE: FEMA 55, COASTAL 

CONSTRUCTION MANUAL, 2000
6-52 MAKING SCHOOLS SAFE AGAINST WINDS 

Figure 6-31 

Threshold with stop and seal 

Figure 6-30 

Interlocking threshold with 

drain pan 

SOURCE: FEMA 55, COASTAL 

CONSTRUCTION MANUAL, 2000

SOURCE: FEMA 55, COASTAL 

CONSTRUCTION MANUAL, 2000

Thresholds can be interlocked with the door (see Figure 6-

30) or thresholds can have a stop and seal (see Figure 6-31). 

In some instances, the threshold is set directly on the floor. 

Where this is appropriate, specify setting the threshold in 

butyl sealant to avoid water infiltration between the threshold 

and floor. In other instances, the threshold is set on a pan 

flashing as discussed in Section 6.10.4. If the threshold 

has weep holes, specify that the weep holes should not be 

obstructed (see Figure 6-30).
MAKING SCHOOLS SAFE AGAINST WINDS 6-53

❍ Adjustable jamb/head 

weatherstripping. This type of 

jamb/head weatherstripping is 

recommended because these units 

have wide sponge neoprene that offers 

good contact with the door (see Figure 

6-32). The adjustment feature also 

helps ensure good contact, provided 

the proper adjustment is maintained.

❍ Meeting stile. At the meeting stile 

of pairs of doors, an overlapping 

astragal weatherstripping offers greater 

protection than weatherstripping that 

does not overlap.

6.11 NON-LOAD BEARING 

WALLS, WALL 

COVERINGS, SOFFITS, 

AND UNDERSIDE OF 

ELEVATED FLOORS

This section addresses exterior non-load bearing walls and provides guidance for interior non-load bearing masonry walls. 

Exterior wall coverings and soffits, as well as the underside of elevated floors, are also discussed.

See Section 6.15.4 for schools located in hurricane-prone regions.

6.11.1 Loads and Resistance

The IBC requires that exterior non-load bearing walls, wall coverings, and soffits (see Figure 6-33) have sufficient strength to resist 

the positive and negative design wind pressure. Architects should 

specify that wall coverings and soffits comply with wind load 

testing in accordance with ASTM E 1233. 

Figure 6-32 Adjustable jamb/head 

 weatherstripping

SOURCE: FEMA 55, COASTAL CONSTRUCTION MANUAL, 2000
6-54 MAKING SCHOOLS SAFE AGAINST WINDS 

Particular care should be given to the design and construction 

of exterior non-load bearing walls constructed of masonry. Although these walls are not intended to carry gravity loads, they 

must be designed to resist the positive and negative wind loads 

in order to avoid collapse. Because of their great weight, when 

these types of walls collapse, they represent a severe risk to life as 

shown in Figure 6-14. 

Special consideration should also be given to interior non-load 

bearing masonry walls. Although these walls are not required by 

building codes to be designed to resist wind loads, if glazing is 

broken, the interior walls could be subjected to significant load as the 

school rapidly becomes fully pressurized. To avoid occupant injury 

(see Figure 6-34), it is recommended that interior non-load bearing 

masonry walls that are adjacent to student areas be designed to 

accommodate loads exerted by a design wind event, using the partially enclosed pressure coefficient. By doing so, wall collapse may 

be prevented if the building envelope is breached. This recommenFigure 6-33 

This suspended metal 

soffit was not designed 

for upward-acting wind 

pressure. 

Depending upon wind direction, soffits can experience either 

positive or negative pressure. Besides the cost of repairing damaged soffits, wind-borne soffit debris can cause property damage 

and injuries.
MAKING SCHOOLS SAFE AGAINST WINDS 6-55

dation is applicable to schools in tornado-prone areas that do not 

have shelter space designed in accordance with FEMA 361, to schools 

located in areas with a basic wind speed greater than 120 mph, and to 

schools that will be used for hurricane shelters.

6.11.2 Durability

Where corrosion is problematic, stainless steel fasteners are recommended for wall and soffit systems. For other components 

(e.g., furring, blocking, struts, and hangars), the following are 

recommended: nonferrous components (such as wood), stainless steel, or steel with a minimum of G-90 hot-dipped galvanized 

coating. In addition, if air can freely circulate in a cavity (e.g., 

above a soffit), access panels are recommended so components 

within the cavity can be periodically observed for corrosion.

6.11.3 Wall Coverings

There are a variety of exterior wall covering options. Brick veneer, 

exterior insulation finish systems (EIFS), metal wall panels, and 

aluminum and vinyl siding have often exhibited poor wind performance. Veneers (such as ceramic tile and stucco) over concrete 

Figure 6-34 

The interior walls of this 

classroom wing were 

constructed of unreinforced 

CMU. 

SOURCE: FEMA 342, OKLAHOMA 

AND KANSAS MIDWEST 

TORNADOES OF MAY 3, 1999, 

1999 
6-56 MAKING SCHOOLS SAFE AGAINST WINDS 

and cement-fiber panels and siding have also blown off. Blow-off 

of wood siding and panels is rare.

Figure 6-35 shows brick veneer that was blown off. The bricks were 

attached to the back-up wall with corrugated metal ties. All of 

the following failure modes are commonly found in the vicinity 

of this type of common failure: 1)The nails pull out of the studs 

(smooth shank nails are typically used, hence they have limited 

withdrawal resistance; 2)The ties do not extend far enough into 

the mortar joint (i.e., the tie is not long enough); 3)Although the 

ties make contact with the mortar, they are not well-bonded to it; 

4)The ties are spaced too far apart; and 5)The ties provide essentially no resistance to compression. Hence, when a great amount 

of positive pressure is applied to the bricks, the brick joints flex. 

This flexing weakens the mortar joint. Walls that have not had 

bricks blown away have been found to be capable of being deflected with hand pressure. Although they look sound, in this 

condition they are very vulnerable to failure. Good reliable wind 

performance of brick veneer is very demanding on the designer 

and applicator.

Figure 6-35 

Failure of brick veneer

SOURCE: FEMA 342, OKLAHOMA 

AND KANSAS MIDWEST 

TORNADOES OF MAY 3, 1999, 

1999
MAKING SCHOOLS SAFE AGAINST WINDS 6-57

Figure 6-36 

EIFS blow-off near a wall 

corner. At one area, the 

metal fascia was also 

blown in.

SOURCE: FEMA 342, OKLAHOMA 

AND KANSAS MIDWEST 

TORNADOES OF MAY 3, 1999, 

1999

Figure 6-36 shows EIFS blow-off. In this case, the expanded 

polystyrene (EPS) was attached to gypsum board, which was attached to metal studs. The gypsum board detached from the 

studs, which is a common EIFS failure mode. When the gypsum 

board on the exterior side of the studs is blown away, it is 

common for gypsum board on the interior side to also be blown 

off. This then allows the school to become fully pressurized 

and allows entrance of wind-driven rain. Other common failure 

modes include separation of the EPS from its substrate and separation of the synthetic stucco from the EPS. Good reliable wind 

performance of EIFS is very demanding on the designer and 

applicator. Maintenance of EIFS and associated sealant joints is 

also demanding in order to minimize reduction of EIFS’ wind 

resistance due to water infiltration.

Another issue associated with EIFS is the potential for misdiagnosis of the wall system. EIFS is sometimes mistaken to be a 

concrete wall. If school personnel believed that an EIFS wall 

covering was a concrete wall and sought shelter from a tornado, 

instead of being protected by several inches of concrete, only two 

layers of gypsum board (i.e., one layer on each side of the studs) 

and a layer of EPS would be between the occupants and windborne debris. The debris could easily penetrate such a wall. 
6-58 MAKING SCHOOLS SAFE AGAINST WINDS 

EIFS can also be applied over concrete or CMU. In this scenario, 

the concrete or CMU could provide adequate missile protection 

provided it was thick enough and adequately reinforced. However, with this wall construction, there is still risk of blow-off of 

the EIFS. As discussed in Section 6.15.4, if the concrete or CMU 

is left exposed, there is no covering to be blown off.

Wind performance of metal wall panels is highly variable. Performance depends upon strength of the specified panel (which 

is a function of material, panel profile, panel width and whether 

or not the panel is a composite) and the adequacy of the attachment (which can either be by concealed clips or exposed 

fasteners). A common problem is excessive spacing between 

clips/fasteners. Clip/fastener spacing should be specified, along 

with the specific type and size of fastener to be used. Figures 6-13 

and 6-43 illustrate metal wall panel problems.

To minimize water infiltration at metal wall panel joints, it is 

recommended that sealant tape be specified at sidelaps when 

the basic wind speed is in excess of 90 mph. However, end laps 

should be left unsealed so that moisture behind the panels can 

wick out. End laps should be a minimum of 3 inches (4 inches 

where the basic wind speed is greater than 120 mph) to avoid 

wind-driven rain infiltration. At the base of the wall, a 3-inch 

(4-inch) flashing should also be detailed, or the panels should 

be detailed to over-lap with the slab or other components by a 

minimum of 3 inches (4 inches).

Vinyl siding blow-off is typically caused by nails spaced too far 

apart and/or the use of vinyl siding that has inadequate wind-resistance. Vinyl siding is available with enhanced wind resistance 

features, such as an enhanced nailing hem, greater interlocking 

area, and greater thickness. 

Secondary Protection. Almost all wall coverings permit the passage of some water past the exterior surface of the covering, 

particularly when rain is wind-driven. Hence, most wall coverings 

should be considered as water-shedding, rather than as water-
MAKING SCHOOLS SAFE AGAINST WINDS 6-59

proofing coverings. To avoid moisture related problems, it is 

recommended that a secondary line of protection with a moisture 

barrier (such as housewrap or asphalt-saturated felt) and flashings around door and window openings be provided. Designers 

should specify that horizontal laps of the moisture barrier be 

installed so that water is allowed to drain from the wall (i.e., the 

top sheet should lap over the bottom sheet so that water running 

down the sheets remains on their outer surface). The bottom of 

the moisture barrier needs to be detailed to allow drainage.

In areas that frequently experience strong winds, enhanced flashing 

details are recommended. Enhancements include use of flashings 

that have extra-long flanges, and use of sealant and tapes. Flashing 

design should recognize that wind-driven water can be pushed vertically. The height to which water can be pushed increases with wind 

speed. Water can also migrate vertically and horizontally by capillary 

action between layers of materials (e.g., between a flashing flange 

and housewrap). It is recommended that designers attempt to determine what type of flashing details have successfully been used in 

the area where the school will be constructed.

If EIFS is specified, it is strongly recommended that it be designed 

with a drainage system that allows for dissipation of water leaks.

6.11.4 Underside of Elevated Floors

If sheathing is applied to the underside of joists or trusses elevated on piles (e.g., to protect insulation installed between 

the joists/trusses), its attachment should be specified in order 

to avoid blow-off. Stainless steel or hot-dip galvanized nails or 

screws are recommended. ASCE 7 does not provide guidance for 

load determination. 

6.12 ROOF SYSTEMS

Because roof covering damage has historically been the most frequent and costly type of wind damage, special attention needs to 

be given to roof system design.
6-60 MAKING SCHOOLS SAFE AGAINST WINDS 

Code Requirements. The IBC requires load resistance of the roof 

assembly to be evaluated by one of the test methods listed in IBC’s 

Chapter 15. Architects are cautioned that designs that deviate 

from the tested assembly (either with material substitutions or 

change in thickness or arrangement) may adversely affect the 

wind performance of the assembly. The IBC does not specify a 

minimum safety factor. However, for the roof system, a safety 

factor of two is recommended. (To apply the safety factor, divide the test load by two to determine the allowable design load. 

Conversely, multiply the design load by two to determine the 

minimum required test resistance.)

For metal panel systems, the IBC requires test methods UL 580 

or ASTM E 1592. It is recommended that architects specify use of 

E 1592 because it is more likely to give a better representation of 

the system’s uplift performance capability. 

Load Resistance. Specifying load resistance is commonly done by 

specifying a Factory Mutual Research (FMR) rating, such as Factory Mutual (FM) 1-75. The first number (“1”) indicates that the 

roof assembly passed the FMR tests for a Class 1 fire rating. The 

second number (“75”) indicates the uplift resistance in psf that 

the assembly achieved during testing. Applying a safety factor of 

two to this example, this assembly would be suitable where the 

design uplift load is 37.5 psf. 

As previously discussed, because of building aerodynamics, the 

highest uplift load occurs at roof corners. The perimeter has a 

somewhat lower load; the field of the roof has the lowest load. 

FMG Data Sheets are formatted so that a roof assembly can be 

selected for the field of the roof. That assembly is then adjusted 

to meet the higher loads in the perimeter and corners by increasing the number of fasteners or decreasing the spacing of 

adhesive ribbons by a required amount; however, this assumes 

that the failure is the result of the pulling-out of the fastener 

from the deck, or that failure is in the vicinity of the fastener 

plate, which may not be the case. Also, the increased number of 

fasteners required by FM may not be sufficient to comply with 
MAKING SCHOOLS SAFE AGAINST WINDS 6-61

the perimeter and corner loads derived from the building code. 

Therefore, if FM resistance data are specified, it is prudent for 

the architect to separately specify the resistance for the field of 

the roof (1-75 in the example above), the perimeter (1-130), and 

the corner (1-190). 

Edge Flashings and Copings. Roof membrane blow-off is almost 

always a result of lifting and peeling of the metal edge flashing or 

coping, which serves to clamp down the membrane at the roof 

edge (see Figure 6-37). Therefore, it is important for the architect 

to carefully consider the design of metal edge flashings, copings, 

and the nailers to which they are attached. ANSI/SPRI ES-1, Wind 

Design Standard for Edge Systems Used in Low Slope Roofing Systems

provides general design guidance, including a methodology for 

determining the outward-acting load on the vertical flange of the 

flashing/coping (ASCE 7 does not provide this guidance). 

Figure 6-37 

The metal edge flashing 

on this modified bitumen 

membrane roof was 

installed underneath the 

membrane, rather than on 

top of it and then stripped 

in. In this location, the 

edge flashing is unable 

to clamp the membrane 

down. At one area, 

the membrane was not 

sealed to the flashing 

(an ink pen was inserted 

into the opening prior to 

photographing). Wind can 

catch the opening and lift 

and peel the membrane. 

A minimum safety factor of three for edge flashings, copings, 

and nailers is recommended for schools. ANSI/SPRI ES-1 also includes test methods for assessing flashing/coping resistance. For 

FMG-insured schools, FMR approved flashing should be used and

Data Sheet 1-49 should also be consulted. 
6-62 MAKING SCHOOLS SAFE AGAINST WINDS 

The traditional edge flashing/coping attachment method relies 

on concealed cleats that can deform under wind load and lead 

to disengagement of the flashing/coping (see Figure 6-38) and 

subsequent lifting and peeling of the roof membrane (as shown 

in Figure 6-11). When a vertical flange disengages and lifts up 

(as shown in Figure 6-38), the edge flashing and membrane are 

very susceptible to failure. Normally, when a flange lifts such as 

shown in Figure 6-38, the failure continues to propagate and the 

metal edge flashing and roof membrane blow off. 

Figure 6-38 

This metal edge flashing 

had a continuous cleat, but 

the flashing disengaged 

from the cleat and the 

vertical flange lifted up. 

However, the horizontal 

flange of the flashing did 

not lift. 

Storm-damage research has revealed that, in lieu of cleat attachment, use of exposed fasteners to attach the vertical flanges of 

copings and edge flashings has been found to be a very effective 

and reliable attachment method (see Figure 6-39). 

If cleats are used for attachment, it is recommended that a bar be 

placed over the roof membrane near the edge flashing/coping 

as illustrated in Figure 6-40. The purpose of the bar is to provide 

secondary protection against membrane lifting and peeling in 

the event that the edge flashing/coping fails. A robust bar specifically made for bar-over mechanically attached single-ply systems 

is recommended. The bar needs to be very well anchored to the 

parapet or deck. Depending upon design wind loads, a spacing 
MAKING SCHOOLS SAFE AGAINST WINDS 6-63

Figure 6-39 

This coping was attached 

with 1⁄4-inch diameter 

stainless steel concrete spikes 

at 12 inches on center. 

When the fastener is placed 

in wood, #14 stainless steel 

screws with stainless steel 

washers are recommended. 

Also, in the corner areas, 

the fasteners should be more 

closely spaced (the spacing 

will depend upon the design 

wind loads). ANSI/SPRI 

ES-1 provides guidance 

on fastener spacing and 

thickness of the coping/

edge flashing.

Figure 6-40 

Continuous bar near the 

edge of edge flashing or 

coping. If the edge flashing 

or coping is blown off, 

the bar may prevent a 

catastrophic progressive 

failure.

SOURCE: FEMA 55, COASTAL 

CONSTRUCTION MANUAL, 2000

between 4 and 12 inches on center is recommended. A gap of a 

few inches should be left between each bar to allow for water flow 

across the membrane. After the bar is attached, it is stripped over 

with a stripping ply.
6-64 MAKING SCHOOLS SAFE AGAINST WINDS 

Gutters. Special design attention needs to be given to uplift 

attachment of gutters, particularly those in excess of 6 inches 

wide. Recommendations are provided in “Honing in on 

hangars,” Professional Roofing, Thomas L. Smith, October 2002, 

pp. 32 (available on-line at www.nrca.net).

Roof System Performance. Storm-damage research has shown 

that sprayed polyurethane foam and liquid-applied roof systems 

are very reliable high-wind performers. If the substrate to which 

the foam or liquid-applied membrane was applied does not lift, 

it is highly unlikely that the sprayed polyurethane foam (SPF) 

or the liquid-applied membrane will blow-off. Both systems are 

also more tolerant of missiles than other systems. Built-up roofs 

(BURs) and modified bitumen systems have also demonstrated 

good wind performance provided the edge flashing/coping 

does not fail (edge flashing/coping failure is common). The 

exception is aggregate surfacing, which is prone to blow-off (see 

Figure 6-11). Modified bitumen adhered to a concrete deck has 

demonstrated excellent resistance to progressive peeling after 

blow-off of the metal edge flashing. Metal panel performance 

is highly variable. Some systems are very wind-resistant, while 

others are quite vulnerable. 

Of the single-ply attachment methods, the paver-ballasted and 

fully adhered methods are the least problematic. Systems with 

aggregate ballast are prone to blow-off, unless care is taken in 

the design of the size of aggregate and the parapet height (see 

Figure 6-8). Performance of protected membrane roofs (PMRs) 

with factory-applied cementitious coating over insulation boards 

is highly variable. When these boards are installed over a looselaid membrane, it is critical that an air retarder be incorporated 

to prevent the membrane from ballooning and disengaging 

the boards. ANSI/SPRI RP-4 (which is referenced in the IBC) 

provides wind guidance for ballasted systems using aggregate, 

pavers, and cementitious-coated boards. 

The National Research Council of Canada, Institute for Research in Construction's Wind Design Guide for Mechanically 
MAKING SCHOOLS SAFE AGAINST WINDS 6-65

Attached Flexible Membrane Roofs, B1049 (2004) provides recommendations related to mechanically attached single-ply and 

modified bituminous systems. B1049 is a very comprehensive 

wind design guide and includes discussion of air retarders, 

which can be effective in reducing membrane flutter, in addition to their beneficial use in ballasted single-ply systems. 

When a mechanically attached system is specified, careful 

coordination with the structural engineer with respect to selection of deck type and thickness is important. If a steel deck is 

specified, it is critical to specify that the membrane fastener 

rows run perpendicular to the steel flanges in order to avoid 

overstressing attachment of the deck to the deck support structure (see Figures 6-41 and 6-42). In Figure 6-42, the flange with 

membrane fasteners carries essentially all of the uplift load 

because of the deck’s inability to transfer any significant load 

to adjacent flanges. Hence, at the joists, the deck fasteners on 

either side of the flange with the membrane fasteners are the 

only connections to the joists that are carrying uplift load. Had 

the membrane fasteners shown in Figure 6-42 been run perpendicular to the deck flanges, each of the fasteners connecting the 

deck to the joists would have been carrying uplift load. 

Figure 6-41 

On this school, the fastener 

rows of the mechanically 

attached single-ply 

membrane ran parallel to 

the top flange of the steel 

deck. Hence, essentially 

all of the row’s uplift load 

was transmitted to only 

two deck fasteners at each 

joist (as illustrated in Figure 

6-42). Because the deck 

fasteners were overstressed, 

a portion of the deck blew 

off and the membrane 

progressively tore.
6-66 MAKING SCHOOLS SAFE AGAINST WINDS 

Figure 6-42 

View of the underside 

of a steel deck. The 

mechanically attached 

single-ply membrane 

fastener rows ran parallel 

to the top flange of the steel 

deck. 

Recommendations related to metal panels is provided in “Insights 

on Metal Roof Performance in High-wind Regions,” Professional 

Roofing, Thomas L. Smith, February 1995, pp. 12 (available on-line 

at www.nrca.net).

Parapet Base Flashings. Loads on parapet base flashings were 

first introduced in the 2002 edition of ASCE 7. The loads on 

base flashings are greater than the loads on the roof covering if 

the parapet’s exterior side is air-permeable. When base flashing 

is fully adhered, it has sufficient wind resistance in most cases. 

However, when base flashing is mechanically fastened, typical 

fastening patterns may be inadequate, depending upon design 

wind conditions (see Figure 6-43). Therefore, it is imperative that base flashing loads be calculated and attachments be 

designed to accommodate the loads. It is also important for designers to recognize and specify different attachment spacings in 

parapet corner regions versus regions between corners. Further 

discussion is provided in “Detailing ASCE 7’s changes,” Professional Roofing, Thomas L. Smith, July 2003, pp. 26 (available 

on-line at www.nrca.net).
MAKING SCHOOLS SAFE AGAINST WINDS 6-67

Lightning Protection Systems. When not adequately integrated 

into a roof system, a lightning protection system can become 

detached from the roof during high winds. The detached system 

can damage the roof covering (see Figure 6-44). In addition, 

a detached system is no longer capable of providing lightning 

protection. Most manufacturers of lightning protection systems 

and most roofing manufacturers provide vague or inadequate 

details for securing a lightning protection system to a roof. 

During prolonged high winds, repeated 

slashing of the membrane by loose 

conductors (“cables”) and puncturing by air 

terminals can result in lifting and peeling of 

the membrane. It is, therefore, important 

to adequately design the attachment 

of the lightning protection system. 

Recommendations pertaining to wind-resistant design, and 

specification and installation of lightning protection systems 

are provided in “Integrating a Lightning Protection System in a 

Roof System,” Thomas L. Smith, 12th International Roofing and 

Waterproofing Conference Proceedings (CD), National Roofing 

Contractors Association, 2002.

Steep-slope Coverings. For discussion 

and recommendations pertaining to steepslope roof coverings, see FEMA 55, Coastal 

Construction Manual, Third Edition, 2000.

Figure 6-43 

The parapet on this school 

was sheathed with metal 

wall panels. The panels 

were fastened at 2 feet 

on center along their 

bottom edge, which was 

inadequate to resist the 

wind load.
6-68 MAKING SCHOOLS SAFE AGAINST WINDS 

Figure 6-44 

This air terminal (“lightning 

rod”) was dislodged and 

whipped around during a 

windstorm. The single-ply 

membrane was punctured 

by the sharp tip in several 

locations.

SOURCE: FEMA, BUILDING TO 

MINIMUM TYPHOON DAMAGE: 

DESIGN GUIDELINES FOR 

BUILDINGS, JULY 1998

Hurricane-prone Regions. See Section 6.15.5 for schools in hurricane-prone regions.

Tornado-prone Regions. In order to reduce the number of windborne missiles, it is recommended that aggregate surfacings, 

pavers, tile, and slate not be specified on schools in tornadoprone regions (as defined in Section 6.7.1; see Figure 6-8).

6.13 WINDOWS AND SKYLIGHTS

This section addresses exterior windows and skylights. See Section 

6.15.6 for schools located in hurricane-prone regions.

6.13.1 Loads and Resistance

The IBC requires the window, curtain wall, or skylight assembly 

(i.e., the glazing, frame, and frame attachment to the wall or roof) 

to have sufficient strength to resist the positive and negative design wind pressure (see Figure 6-45). Architects should specify that 

these assemblies comply with wind load testing in accordance with 

ASTM E 1233. It is important to specify an adequate load path and 

to check its continuity during submittal review.
MAKING SCHOOLS SAFE AGAINST WINDS 6-69

Figure 6-45 

Two complete windows, 

including their frames, 

blew out. The frames 

were attached with an 

inadequate number of 

fasteners, which were 

somewhat corroded.

SOURCE: FEMA, BUILDING TO 

MINIMUM TYPHOON DAMAGE: 

DESIGN GUIDELINES FOR 

BUILDINGS, JULY 1998

In tornado-prone regions, some school districts may desire to 

have laminated glazing installed at exterior openings in order 

to provide wind-borne debris protection during weak tornadoes. 

Laminated glazing may also offer protection during strong tornadoes, but should not be relied upon for violent tornadoes. Further 

discussion is provided in Section 6.15.6.

6.13.2 Durability

Where corrosion is problematic, anodized aluminum or stainless 

steel frames and stainless steel frame anchors are recommended.

6.13.3 Water Infiltration

When heavy rain accompanies high winds (e.g., thunderstorms, 

tropical storms, and hurricanes), it can cause wind-driven water infiltration problems; the magnitude of the problem increases with 

the wind speed. Leakage can occur at the glazing/frame interface, 

at the frame itself, or between the frame and wall. When the basic 

wind speed is greater than 120 mph, because of the very high design wind pressures and numerous opportunities for leakage path 

development, some leakage should be anticipated when design 

wind speed conditions are approached. 
6-70 MAKING SCHOOLS SAFE AGAINST WINDS 

The challenge with windows and curtain walls is successful integration between these elements and the walls. To the extent possible, 

detailing of the interface between the wall and the window or 

curtain wall units should rely on sealants as the secondary line of 

defense against water infiltration, rather than making the sealant 

the primary protection. 

When designing joints between walls and windows and curtain 

wall units, consider the shape of the sealant joint (i.e., a square 

joint is typically preferred) and the type of sealant to be specified. The sealant joint should be detailed so the sealant is able 

to bond on only two opposing surfaces (i.e., a backer rod or 

bond-breaker tape should be specified). For concealed sealants, 

butyl is recommended. For exposed sealants, polyurethane is 

recommended. During installation, cleanliness of the sealant 

substrate is important (particularly if polyurethane or silicone 

sealants are specified), as well as tooling of the sealant. ASTM E 

2112 provides guidance on design of sealant joints, as well other 

information pertaining to installation of windows, including the 

use of sill pan flashings with end dams and rear legs (see Figure 

6-46). It is recommended that designers use ASTM E 2112 as a 

design resource.

Figure 6-46 

View of a typical window 

sill pan flashing with 

end dams and rear legs. 

Windows that do not have 

nailing flanges should 

typically be installed over a 

pan flashing.

SOURCE: ASTM E2112
MAKING SCHOOLS SAFE AGAINST WINDS 6-71

Sealant joints can be protected with a removable stop as illustrated in Figure 6-47. The stop protects the sealant from direct 

exposure to the weather and reduces the wind-driven rain demand on the sealant.

Figure 6-47 

Protection of sealant with 

a stop. The stop retards 

weathering of the sealant 

and reduces the winddriven rain demand on the 

sealant.

SOURCE: FEMA 55, COASTAL 

CONSTRUCTION MANUAL, 2000

Where water infiltration protection is particularly demanding and 

important, it is recommended that on-site water infiltration testing 

in accordance with ASTM E 1105 be specified.

6.14 EXTERIOR-MOUNTED MECHANICAL, 

ELECTRICAL, AND COMMUNICATIONS 

EQUIPMENT

Exterior-mounted mechanical (e.g., exhaust fans, HVAC units, 

relief air hoods, boiler stacks), electrical, and communications 

equipment (e.g., light fixtures, antennae, satellite dishes) are 

often damaged during high winds. Damaged equipment can impair the use of the school, the equipment can become missiles, 

and water can enter the facility where equipment was displaced 

(see Figures 6-19 and 6-48).

Problems typically relate to inadequate equipment anchorage, inadequate strength of the equipment itself, and corrosion.
6-72 MAKING SCHOOLS SAFE AGAINST WINDS 

Figure 6-48 

The rooftop mechanical 

equipment on this school 

was blown over. The 

displaced equipment can 

puncture the roof membrane 

and, as in this case, 

rain can enter the school 

through the large opening 

that is no longer protected 

by the equipment. 

6.14.1 Loads and Attachment

Rooftop Equipment. Criteria for determining loads on rooftop 

equipment were added to the 2002 edition of ASCE 7. A minimum safety factor of three is recommended for the design of 

equipment anchorage.

To anchor membrane fans, small HVAC units, and relief air hoods, 

the following minimum prescriptive attachment schedule is 

recommended:

❍ For curb-mounted units, specify #14 screws with gasketed washers.

❍ For curbs with sides less than 12 inches, specify one screw at 

each side of the curb.

❍ For curbs between 12 inches and 24 inches, specify two screws 

per side. 

❍ For curbs between 24 inches and 36 inches, specify three 

screws per side. 

❍ For units that have flanges attached directly to the roof, 

attachment with #14 pan-head screws is recommended. A 

minimum of two screws per side, with a maximum spacing of 

12 inches on center is recommended.
MAKING SCHOOLS SAFE AGAINST WINDS 6-73

Figure 6-49 illustrates the use of supplemental securement 

straps to anchor equipment. The supplemental attachment was 

marginal; the straps were too light and the fasteners used to 

secure them were corroded. This illustrates the validity of the 

supplemental securement, and it also illustrates the need to 

execute the securement with attention to detail. In lieu of one 

screw at each end of the strap, two side-by-side screws offer a 

stronger and more reliable connection (this of course requires a 

slightly wider strap).

Figure 6-49 

This HVAC equipment 

had two supplemental 

securement straps. Both 

straps are still on this unit, 

but some of the other units 

on the roof had broken 

straps. 

SOURCE: FEMA, BUILDING TO 

MINIMUM TYPHOON DAMAGE: 

DESIGN GUIDELINES FOR 

BUILDINGS, JULY 1998 

Electrical and Communications Equipment. Damage to exterior-mounted electrical equipment is infrequent, in large part, 

because of the small size of most equipment (e.g., disconnect 

switches). Exceptions are communication masts (see Figure 

6-50), surveillance cameras, service masts, and satellite dishes. 

These failures are typically caused by failure to perform wind 

load calculations and anchorage design. Service mast failure is 

typically caused by collapse of overhead power lines; this can 

be avoided by underground service. Where overhead service 

is provided, it is recommended that the service mast not penetrate the roof. Otherwise, a downed service line could pull 

the mast and rupture the roof membrane.
6-74 MAKING SCHOOLS SAFE AGAINST WINDS 

Figure 6-50 

The communications mast 

on this school was pulled 

out of the deck, resulting 

in a progressive peeling 

failure of the fully adhered 

single-ply membrane. There 

are several exhaust fans in 

the background that were 

blown off their curbs, but 

were retained on the roof 

by the parapet.

SOURCE: FEMA, BUILDING TO 

MINIMUM TYPHOON DAMAGE: 

DESIGN GUIDELINES FOR 

BUILDINGS, JULY 1998 

ASCE 7 provides load calculation criteria for trussed towers. The 

ASCE 7 criteria are consistent with ANSI/EIA/TIA-222-E. The ASCE 

7 approach is a simplified procedure. The IBC allows use of either 

approach. ASCE 7 does not provide guidance for on-site power 

distribution poles nor for light fixture poles. However, the National 

Electrical Safety Code, ANSI/C2 provides guidance for determining 

wind loads on power poles. The AASHTO Standard Specification for 

Structural Support for Highway Signs, Luminaries and Traffic Signals provides guidance for determining wind loads on light fixture poles.

See Section 6.8.1 regarding siting of light fixture poles, power 

poles, and electrical and communications towers.

6.14.2 Equipment Strength

It is common for equipment components such as fan cowlings and access panels to be blown off during storms. Design 

of these elements is the responsibility of the equipment 

manufacturer. Although poor equipment performance has 

been documented, manufacturers have not offered enhanced 

equipment for high-wind regions. Therefore, it is incumbent 

upon the architect/engineer to give special design attention 

to equipment strength.
MAKING SCHOOLS SAFE AGAINST WINDS 6-75

Damage investigations have revealed that cable tie-downs have 

been effective in securing fan cowlings when a sufficiently strong 

cable and anchor details were used (see Figure 6-51). For fan 

cowlings less than 4 feet in diameter, 1/8-inch diameter stainless 

steel cables are recommended. For larger cowlings, use 3/16-inch 

diameter cables. When the basic wind speed is 120 mph or less, 

specify two cables. Where the basic wind speed is greater than 

120 mph, specify four cables. (As an alternative to cables, heavy 

stainless steel straps could be screwed to the cowling and curb.) 

To minimize leakage potential at the anchor point, it is recommended that the cables be anchored to the equipment curb 

(rather than anchored to the roof deck). The attachment of the 

curb itself also needs to be designed and specified. 

Figure 6-51 

To overcome blow-off of 

the fan cowling, which is 

a common problem, this 

cowling was attached to the 

curb with cables. The curb 

needs to be adequately 

attached to carry the wind 

load exerted on the fan.

SOURCE: FEMA, BUILDING TO 

MINIMUM TYPHOON DAMAGE: 

DESIGN GUIDELINES FOR BUILDINGS, 

JULY 1998 

To minimize blow-off of equipment access panels, job-site modification will typically be necessary (such as the attachment of 

hasps and locking devices such as a carabineer). The modification 

details will need to be tailored for the equipment, which may necessitate detail design after the equipment has been delivered to 

the job site. Alternatively, factored loads on the equipment could 

be specified, along with the requirement for the manufacturer to 

demonstrate compliance with the load requirement.
6-76 MAKING SCHOOLS SAFE AGAINST WINDS 

6.14.3 Durability 

To avoid corrosion-induced blow-off, it is recommended that 

exterior-mounted mechanical, electrical, and communications 

equipment be nonferrous, stainless steel, or steel with minimum G90 hot-dip galvanized coating for the equipment itself, equipment 

stands, anchors, and fasteners. When equipment with enhanced 

corrosion protection is not available, the designer should advise 

the school district that periodic equipment maintenance and inspection is particularly important to avoid advanced corrosion and 

subsequent equipment damage during a windstorm.

The recommendations given in Sections 6.8 through 6.14 are summarized in Table 6-1.

Table 6-1: Summation of Risk Reduction Design Methods

Site See Section 6.8.1.

Exposure Locate in Exposure B if possible. Avoid escarpments and upper half of hills.

Are there trees or poles? Locate to avoid blow-down on school.

Site access Minimum of two roads.

Are there, or will there eventually be 

portables?

Locate downwind of school.

General design issues See Section 6.8.2

Calculate loads on MWFRS, building 

envelope and rooftop equipment

Use ASCE 7 or local building code, whichever procedure results in highest loads.

Determine load resistance via calculations 

and/or test data

Give load resistance criteria in contract documents, and clearly indicate load path 

continuity.

Durability Give special attention to material selection and detailing to avoid problems due to 

corrosion, wood decay, and termite attack.

Rain penetration Detail to minimize wind-driven rain penetration into the building envelope.
MAKING SCHOOLS SAFE AGAINST WINDS 6-77

Table 6-1: Summation of Risk Reduction Design Methods (continued)

Structural Systems (MWFRS) See Section 6.9.

Is it a pre-engineered structural system? Take special steps to ensure structure is not vulnerable to progressive collapse.

Are there exterior bearing walls? Design as MWFRS and Components and Cladding. Reinforce CMU. Sufficiently connect 

precast concrete panels.

Roof decks Concrete, steel, or wood sheathing is recommended. Attach steel decks with screws. 

Use special fasteners for wood sheathing. Anchor precast concrete to resist uplift 

load. For precast Tees, design reinforcing to resist uplift. If FMG-rated assembly, deck 

must comply with FMG criteria. If mechanically attached roof membrane, refer to 

recommendations in National Research Council of Canada, Institute for Research in 

Construction, Wind Design Guide for Mechanically Attached Flexible Membrane Roofs, 

B1049, 2004.

Exterior Doors and Non-Load Bearing 

Exterior Walls

See Section 6.10 and 6.11.

Door, frame and frame fasteners Resist positive and negative design load, verified by ASTM E 1233 testing. Specify type, 

size, and spacing of frame fasteners.

Water infiltration Consider vestibules, door swing, weatherstripping. Refer to ASTM E 2112 for design 

guidance.

Are there exterior non-load bearing walls, 

wall coverings, soffits, or elevated floors?

See Section 6.11.

Load resistance Resist positive and negative design load, verified by ASTM E 1233 testing. Design as 

Components and Cladding.

Secondary protection Provide moisture barrier underneath wall coverings that are water-shedding.

Roof Systems See Section 6.12.

Testing Avoid designs that deviate from a tested assembly. If deviation is evident, perform 

rational analysis. For metal panel systems, test per ASTM E 1592. 

Edge flashings and copings Follow ANSI/SPRI ES-1. Use a safety factor of three. Consider face-fasteners (Figure 6-

39). Consider continuous bars (Figure 6-40).

System selection Select systems that offer high reliability, commensurate with the wind-regime where the 

school is located.

Are there parapet base flashings? Calculate loads and resistance. This is particularly important if base flashing is 

mechanically attached.

Is there a lightning protection system? Design and specify anchorage to the roof.

Is there a steep-slope roof system? See Coastal Construction Manual, Third Edition, FEMA 55, 2000.
6-78 MAKING SCHOOLS SAFE AGAINST WINDS 

Windows and Skylights See Section 6.13.

Glazing, frame, and frame fasteners Resist positive and negative design load, verified by ASTM E 1233 testing. Specify type, 

size, and spacing of frame fasteners.

Water infiltration Carefully design juncture between walls and windows/curtain walls. Avoid relying on 

sealant as the first line of defense. Refer to ASTM E 2112 for design guidance. Where 

infiltration is demanding, consider on-site water infiltration testing per ASTM E 1105.

Exterior-mounted Mechanical, 

Electrical, and Communications 

Equipment

See Section 6.14.

Load resistance Specify anchorage of all rooftop and wall-mounted equipment. Use a safety factor of 

three for rooftop equipment anchorage.

Equipment strength Specify cable tie-downs for fan cowlings. Specify hasps and locking devises for 

equipment access panels. 

Electrical service mast Avoid penetration through the roof.

After Completion of Contract 

Documents

Peer review Consider peer review. See Section 6.8.3.

Submittals Ensure required submittals are submitted and that they include the necessary 

information. Verify that each submittal demonstrates development of a load path 

through the system and into its supporting element. See Section 6.8.4.

Field observations Analyze design to determine which elements are critical to ensuring high-wind 

performance. Determine observation frequency of critical elements. See Section 6.8.4.

Post-occupancy inspections, maintenance, 

and repair

Advise the school administration of the importance of periodic inspections, special 

inspections after unusually high winds, maintenance, and timely repair. See Section 

6.8.5.

Table 6-1: Summation of Risk Reduction Design Methods (continued)
MAKING SCHOOLS SAFE AGAINST WINDS 6-79

6.15 SCHOOLS LOCATED IN HURRICANEPRONE REGIONS 

The IBC, through ASCE 7, prescribes that exterior glazing in 

schools in wind-borne debris regions be provided with windborne debris protection (either by use of laminated glass or 

shutters, as discussed in Section 6.15.6). Schools in hurricaneprone regions also have to be designed for a 100-year mean 

recurrence interval wind event if they are to be used as shelters. 

These are the only hurricane-related requirements currently in 

the IBC. These requirements do not provide adequate protection to occupants in a school during a hurricane, because the 

missile requirements only pertain to glazing. Hence, a codecompliant school can be designed, yet still allow the entrance of 

missiles through the roof or walls. To account for this deficiency, 

recommendations are given below regarding missile penetration 

through exterior walls and the roof. For a more conservative hurricane shelter, refer to FEMA 361.

Publication 4496 by the American Red Cross (ARC) provides 

information regarding assessing existing buildings for use as hurricane shelters. Unless a school has been specifically designed for 

use as a shelter, it should only be used as a last resort and only if 

the school meets the criteria given in ARC 4496.

Schools located in hurricane-prone regions should receive special 

design attention because of the unique characteristics of this type 

of windstorm. In addition to being capable of delivering very high 

winds, hurricanes can cause strong winds for many hours, which 

can eventually lead to fatigue failure. The direction of the wind 

can also change, thereby increasing the probability that the wind 

will approach the school at the most critical angle. Hurricanes 

also typically generate a large amount of missiles, which can be 

very damaging to schools and cause injury or death. 

For schools in hurricane-prone regions that will be used for a 

hurricane shelter and/or for emergency response after a storm, 

the following design parameters are recommended (these 
6-80 MAKING SCHOOLS SAFE AGAINST WINDS 

recommendations are in addition to the recommendations previously given in Sections 6.8 through 6.14):

1. During the design phase, the architect should determine 

from the school district whether or not the school will be 

designated or used as a shelter or emergency response 

facility. The school should only be used for a shelter if it was 

designed for that purpose. 

2. For schools in coastal Alaska and other areas that experience 

frequent high wind events (such as parts of Colorado), 

several of the following recommendations are also applicable 

to these schools, with the exception of the wind-borne debris 

recommendations.

6.15.1 Design Loads 

For the importance factor, use a value of 1.15.

6.15.2 Structural Systems 

Because of the exceptionally good wind performance that reinforced cast-in-place concrete structures offer, a reinforced 

concrete roof deck and reinforced concrete and/or reinforced 

and fully grouted CMU exterior walls are recommended. 

In order to achieve enhanced missile resistance, the following 

roof decks are recommended, in descending order of preference: cast-in-place concrete, precast concrete, and concrete 

topping over steel decking. For exterior walls, the following are 

recommended: 6-inch (minimum) thick concrete reinforced 

with #4 rebars at 12 inches on center each way, or 8-inch (minimum) thick fully grouted CMU reinforced with #4 rebars in 

each cell.

6.15.3 Exterior Doors

For glazing in doors, see the recommendations in Section 6.15.6.
MAKING SCHOOLS SAFE AGAINST WINDS 6-81

Although the ASCE-7 wind-borne debris provisions only apply 

to glazing within a portion of hurricane-prone regions, it is 

recommended that all schools that will be used for evacuation 

shelters within the entire hurricane-prone region comply with 

the following recommendation: To minimize the potential of 

missiles penetrating exterior doors and striking people within 

the school, it is recommended that doors without glazing and 

the unglazed portions of doors with glazing be designed to 

resist the missile loads specified in ASTM E 1996 and that they 

be tested in accordance with ASTM E 1886. The test assembly 

should include the door, door frame and hardware. Further 

information on missile resistance of doors is found in FEMA 361, 

Design and Construction Guidance for Community Shelters.

6.15.4 Non-load Bearing Walls, Wall Coverings, 

and Soffits 

In order to achieve enhanced missile resistance, the following 

types of exterior walls are recommended: reinforced cast-in-place 

concrete, or reinforced and fully grouted CMU. 

To minimize long-term problems with non-load bearing walls, wall 

coverings, and soffits, it is recommended that non-load bearing 

exterior walls, wall coverings, and soffits be avoided to the extent 

possible. Reinforced concrete or CMU offers greater reliability 

(i.e., they have no coverings that can be blown off). 

6.15.5 Roof Systems

The following types of roof systems are recommended on schools in 

hurricane-prone regions because they are more likely to avoid water 

infiltration if the roof is hit by wind-borne debris. Also, the following 

systems are less likely to become sources of wind-borne debris:

❍ In tropical climates where insulation is not needed above 

the roof deck: 1) liquid-applied membrane over cast-in-place 

concrete deck, or 2) modified bitumen membrane torched 

directly to cast-in-place concrete deck.
6-82 MAKING SCHOOLS SAFE AGAINST WINDS 

❍ Install a secondary membrane over a concrete deck (if another 

type of deck is specified, a cover board may be needed over 

the deck). Seal the secondary membrane at perimeters and 

penetrations. Specify a minimum 2-inch thick rigid insulation 

and a layer of 5/8-inch thick glass mat gypsum roof board 

over the secondary membrane to absorb missile energy. If the 

primary membrane is punctured during a storm, the secondary 

membrane should provide watertight protection unless the 

roof is hit with missiles of very high energy. A modified bitumen 

membrane is recommended for the primary membrane because 

of its enhanced resistance to puncture by small missiles.

❍ For an SPF roof system over a concrete deck, specify that 

the foam be a minimum of 3 inches thick to avoid missile 

penetration through the entire layer of foam.

❍ For a PMR, it is recommended that pavers weighing a 

minimum of 22 psf be specified. In addition, base flashings 

should be protected with metal. Parapets are recommended 

at roof edges. The parapet should be at least 3 feet high or 

higher if so indicated by ANSI/SPRI RP-4. Note: If the basic 

wind speed exceeds 130 mph, a PMR is not recommended on 

schools in hurricane-prone regions.

❍ For structural metal roof panels with concealed clips, it is 

recommended that mechanically seamed ribs spaced at 12 

inches on center over a concrete deck be specified. If a steel 

deck is specified, specify a self-adhering modified bitumen 

membrane and 3-inch thick rigid insulation, followed by the 

metal panels installed on wood nailers. At the self-adhering 

membrane laps, specify metal strips over the deck where the 

laps do not occur over the deck ribs, or specify a suitable 

cover board between the deck and self-adhering membrane. 

If the metal panels are punctured during a storm, the 

secondary membrane should provide watertight protection 

unless the roof is hit with missiles of very high energy. Note: 

Architectural metal panels are not recommended on schools 

in hurricane-prone regions.
MAKING SCHOOLS SAFE AGAINST WINDS 6-83

In order to avoid the possibility of roofing debris blowing off and 

striking people arriving at the school during the storm, the following types of roof coverings are not recommended: aggregate 

surfacings (either on BUR [shown in Figure 6-11], single-plies 

[shown in Figure 6-8] or SPF), lightweight concrete pavers, cementitious-coated insulation boards, slate, and tile (see Figure 

6-52). Wind-borne debris from heavy roof coverings such as tiles 

have great potential to cause serious injury to people arriving at a 

school during a hurricane or other high wind event.

Figure 6-52 

These wire-tied tiles were 

installed over a concrete 

deck. They were attached 

with stainless steel clips at 

the perimeter rows and all 

of the tiles had tail hooks. 

Adhesive was also used 

between the tail and head 

of the tiles. 

SOURCE: FEMA, BUILDING TO 

MINIMUM TYPHOON DAMAGE: 

DESIGN GUIDELINES FOR 

BUILDINGS, JULY 1998 

Because mechanically attached and air-pressure equalized singleply membrane systems are susceptible to massive progressive 

failure after missile impact (see Figure 6-53), these systems are 

not recommended on schools in hurricane-prone regions. Fully 

adhered single-ply membranes are also very vulnerable to missiles 

(see Figure 6-54); therefore, they also are not recommended unless they are ballasted with pavers. 
6-84 MAKING SCHOOLS SAFE AGAINST WINDS 

Figure 6-53 

At this school, a missile 

struck the fully adhered lowsloped roof (see arrow) and 

slid into the steep-sloped 

reinforced mechanically 

attached single-ply 

membrane. A large area of 

the mechanically attached 

membrane was blown 

away due to progressive 

membrane tearing.

Figure 6-54 

This fully adhered singleply membrane was 

struck by a large number 

of missiles during a 

hurricane.

6.15.6 Windows and Skylights

ASCE 7 requires the use of impact-resistant glazing (i.e., laminated glass) or shutters in wind-borne debris regions. ASCE 7 

refers to ASTM E 1996 for missile loads and to ASTM E 1886 for 

the test method to be used to demonstrate compliance with the E 
MAKING SCHOOLS SAFE AGAINST WINDS 6-85

1996 load criteria. In addition to testing for impact resistance, the 

window unit is subjected to pressure cycling after missile impact to 

evaluate whether or not the window can still resist wind loads.

If wind-borne debris glazing protection is provided by shutters, 

the glazing is still required by ASCE 7 to meet the positive and 

negative design air pressures.

For those schools that desire to provide blast-resistant glazing, the 

windows and glazed doors can be designed to accommodate wind 

pressure, missile loads, and blast pressure. However, the window and 

door units need to be tested for missile loads and cyclic air pressure, 

as well as for blast. A unit that meets blast criteria will not necessarily 

meet the E 1996 and E 1886 criteria, and vice versa. 

With the advent of building codes requiring glazing protection 

in wind-borne debris regions, a variety of shutter designs have 

entered the market. Figure 6-55 illustrates an effective shutter. A 

metal track was permanently mounted to the wall above and below 

the window frame. Upon notification of an approaching hurricane, the metal shutter panels were inserted into the frame and 

locked into position with wing nuts. 

Figure 6-55 

View of a metal shutter 

designed to provide missile 

protection for windows
6-86 MAKING SCHOOLS SAFE AGAINST WINDS 

Shutters typically have a lower initial cost than laminated glass. 

However, unless the shutter is permanently anchored to the 

school (e.g., an accordion shutter), space will be needed to store 

the shutters. Also, when a hurricane is forecast, costs will also 

be incurred each time shutters are installed and removed afterward. To avoid the difficulty of installing shutters on upper-level 

glazing, motorized shutters could be specified, although laminated glass may be more economical in these locations. 

6.15.7 Emergency Power

Schools intended for use as shelters and/or emergency response 

after a storm should be equipped with an emergency generator.

6.15.8 Construction Contract Administration

It is important for the school district to obtain the services of a 

professional contractor who will execute the work described in the 

contract documents in a diligent and technically proficient manner. 

The frequency of field observations and extent of special inspections and testing should be greater than those employed on 

schools that are not designated as shelters.

6.15.9 Periodic Inspections, Maintenance, and 

Repair

The recommendations previously given for periodic and 

post-storm inspections, maintenance, and repair are critically 

important for schools used as shelters and emergency response 

after a storm because, if failure occurs, the risk of injury or death 

to occupants is great, and the needed continued operation of the 

school would be jeopardized.

The recommendations given in Section 6.15 are summarized in 

Table 6-2. These recommendations are in addition to those given 

in Sections 6.8 to 6.14, as summarized in Table 6-1.
MAKING SCHOOLS SAFE AGAINST WINDS 6-87

Table 6-2: Summation of Design of Schools Used for Hurricane Shelters and/or for Emergency Response After a Storm

For wind-load calculations Use an importance factor of 1.15.

Structural system Reinforced cast-in-place concrete is recommended. If roof deck is not cast-in-place, pre-cast 

concrete or concrete topping over steel decking is recommended. 

Exterior walls Reinforced concrete or fully grouted and reinforced CMU is recommended, without wall 

coverings other than paint.

Exterior doors Designed and tested to resist missiles. 

Roof covering Avoid aggregate surfacings, lightweight concrete pavers, cementitious-coated insulation 

boards, slate and tile. Avoid single-ply membranes unless ballasted with heavy pavers. Design 

a roof covering that can accommodate missiles – see Section 6.15.5.

Exterior windows and skylights Laminated glass or shutters designed and tested to resist missiles. If equipped with shutters, 

glazing is still required to resist wind pressure loads.

Emergency power School equipped with an emergency generator.

Construction contract 

administration

Construction executed by professional contractor and subcontractors. More frequent field 

observations, special inspections and testing.

Periodic inspections, 

maintenance, and repair

After construction, diligent periodic inspections and special inspections after storms. Diligent 

maintenance and prompt execution of needed repairs. 

Is enhanced occupant protection 

sheltering desired?

For a more conservative hurricane shelter, refer to FEMA 361, Design and Construction 

Guidance for Community Shelters.
6-88 MAKING SCHOOLS SAFE AGAINST WINDS 

6.16 DESIGN FOR TORNADO SHELTERS

Tornado risk assessment and tornado-prone 

regions were discussed in Section 6.7 and the 

cost of tornado shelters was discussed in Section 

6.5.2. Following up on those discussions, strong 

and violent tornadoes produce wind speeds that 

are substantially greater than those delivered 

by the strongest hurricanes; hence, the wind 

pressures that these tornadoes exert on buildings 

is tremendous and far exceed the minimum 

pressures required by building codes. In addition, strong and 

violent tornadoes can generate very powerful missiles (see Figure 

6-56), including vehicles. The missile sticking out of the roof in the 

foreground of Figure 6-56 is a double 2-inch by 6-inch. The portion 

sticking out of the roof is 13 feet long. It penetrated a ballasted 

ethylene propylene diene monomer (EPDM) membrane and 

approximately 3 inches of polyisocyanurate roof insulation and 

the steel roof deck. The missile laying on the roof just beyond is 2 

inches by 10 inches by 16 feet long. 

Missile loads that are used for the design of tornado shelters are significantly greater than the missile loads used for the design of glazing 

protection in wind-borne debris regions of hurricane-prone regions.

Terrorist threat: If it is desired to 

incorporate a tornado shelter, and if it 

is also desired for the shelter to provide 

protection from terrorism, refer to FEMA 

428 and 453 for additional shelter 

enhancements.

Figure 6-56 

A violent tornado passed 

by this high school and 

showered the roof with 

missiles.

SOURCE: FEMA 342, OKLAHOMA 

AND KANSAS MIDWEST 

TORNADOES OF MAY 3, 1999, 1999
MAKING SCHOOLS SAFE AGAINST WINDS 6-89

8 It should be realized that, unless the refuge area was specifically designed as a tornado shelter, 

occupants in a “best available refuge area” are vulnerable to injury or death.

As discussed in Section 6.5.2, FEMA 361, Design and Construction 

Guidance for Community Shelters, includes software for assessing the 

benefit/cost ratio of incorporating specially designed tornado 

shelters within schools. In addition, it includes comprehensive 

information regarding the design of shelters. If shelter design is 

contemplated, use of FEMA 361 is recommended. 

Existing Schools without Tornado Shelters. Where the number of 

recorded F3, F4, and F5 tornadoes per 3,700 square miles is one 

or greater (see Figure 6-2), if the school does not have a tornado 

shelter, the best available refuge areas should be identified. FEMA 

431, Tornado Protection, Selecting Refuge Areas in Buildings provides 

useful information for school administrators, and for architects 

and engineers who perform evaluations of existing schools.

To minimize deaths and injuries of students, faculty, and other 

occupants, it is critically important that the best available refuge 

areas be pre-identified by a qualified architect/engineer.8 Once 

identified, those areas need to be clearly marked so that occupants can quickly seek refuge. Don’t wait for the arrival of a 

tornado on the school grounds to try to find the best available 

refuge areas; by that time, it is too late. If refuge areas have not 

been pre-identified, occupants can easily take cover in areas that 

can become death traps (see Figure 6-57).

When a true shelter is desired for a school that does not have 

one, retrofitting a shelter within the school can be very expensive. 

An economical alternative is an addition to the existing school 

that can function as a shelter as well as serve another purpose. 

This approach works well for smaller schools, but, for a very large 

school, construction of two or more shelter additions should 

be considered in order to reduce the time it takes to reach the 

shelter (often there is ample warning time, but sometimes an 

approaching tornado is not noticed until a couple of minutes before it strikes).
6-90 MAKING SCHOOLS SAFE AGAINST WINDS 

Figure 6-57 

View of an elementary 

school corridor after 

passage of a violent 

tornado. Although 

corridors sometimes offer 

protection, they can be 

death traps as illustrated in 

this figure (fortunately the 

school was not occupied 

when it was struck). 

SOURCE: FEMA 342, OKLAHOMA 

AND KANSAS MIDWEST 

TORNADOES OF MAY 3, 1999, 

1999

The recommendations given in Section 6.16 are summarized 

in Table 6-3 .

Portable Classrooms. Portable classrooms should not be occupied during times when a 

tornado watch has been issued by the National Weather Service (a watch means that conditions 

are favorable for tornado development). Do not wait for issuance of a tornado warning (i.e., a 

tornado has been spotted) by the National Weather Service to seek refuge in the main school 

building. If a tornado is nearby, students could be caught outdoors. 

Table 6-3: Summation of Design for Tornado Shelters

Proposed New School

1. Is proposed school in a tornado-prone region: yes or no? If yes, 

go to step 2.

See Section 6.7.1 for decision analysis.

2. If yes, perform benefit/cost analysis to assist in deciding whether 

or not to incorporate a shelter(s) within the school.

See FEMA 361, Design and Construction Guidance for Community 

Shelters, benefit/cost analysis.

3. Perform steps 1 and 2 prior to setting project budget. If sheltering is not considered until after setting the budget, funds 

may not be available.

4. It is decided to incorporate a shelter(s). Refer to FEMA 361, Design and Construction Guidance for 

Community Shelters, for design guidance.
MAKING SCHOOLS SAFE AGAINST WINDS 6-91

Table 6-3: Summation of Design for Tornado Shelters (continued) 

Existing schools without specifically designed tornado shelters

1. If 1 or more F3-F5 tornadoes per 3,700 square miles, pre-identify 

best available refuge areas.

See Figure 6-2 for history frequency and FEMA 431, Tornado 

Protection, Selecting Refuge Areas in Buildings for identification 

guidance.

2. If 1 or more F3-F5 tornadoes per 3,700 square miles, consider 

incorporating a shelter(s) within a new building addition(s).

See FEMA 361, Design and Construction Guidance for Community 

Shelters, for benefit/cost analysis and design guidance.

6.17 REMEDIAL WORK ON EXISTING SCHOOLS

Section 6.6.1 discussed prioritizing and Section 6.6.2 discussed cost. 

Following up on those discussions, many existing schools need 

building envelope component strengthening or structural strengthening. The need for this work is due either to deterioration over time 

and/or inadequate facility strength at the time the school was built. 

It is prudent for school districts to have their existing facilities 

evaluated. This also applies to recently constructed schools that 

are located in an area where the basic wind speed is greater than 

90 mph (peak gust), and those schools that will be used for emergency response after a storm and schools that will be used for a 

hurricane shelter.

For new schools, areas of concern would typically be the 

building envelope and exterior-mounted mechanical, electrical, and communications equipment. By identifying 

weaknesses and prioritizing and executing the work, many 

failures can be averted. A proactive approach can save significant sums of money and decrease the number of instances 

when schools are impaired or immobilized after a storm. 

For roofs with weak metal edge flashing or coping attachment, face-attachment of the edge flashing/coping (as shown 

in Figure 6-39) is a cost-effective approach to greatly improve 

wind-resistance of the roof system. Fastening rooftop equip-
6-92 MAKING SCHOOLS SAFE AGAINST WINDS 

ment to curbs is a cost-effective approach to avoid the type of 

problems shown in Figure 6-19.

During planned roof covering replacement, by tearing off the existing roof covering rather than re-covering, there is the opportunity 

to evaluate the structural integrity of the deck and deck attachment 

and upgrade its attachment if necessary. Many older decks are poorly 

attached (Figure 6-58); hence, if their attachment is not upgraded, 

blow-off of the deck and the new roof covering could occur. The two 

deck panels shown in Figure 6-58 blew away because their attachment 

to the roof structure was inadequate. An SPF roof covering was 

over the deck panels that blew away because of the characteristics 

of this type of covering, membrane propagation failure did not 

occur, as would have been the case with built-up, modified bitumen, 

or single-ply roof membranes. Cementitious wood-fiber decks were 

commonly used on schools built in the 1950s and 1960s. Decks 

constructed during that era typically had very limited uplift resistance due to weak connections to the support structure. 

Design guidance pertaining to existing decks is presented 

in “Uplift Resistance of Existing Roof Decks: Recommendations for 

Enhanced Attachment During Reroofing Work,” RCI Interface, 

Thomas L. Smith, January 2003, pp. 14.

Figure 6-58 

This school had a 

cementitious wood-fiber 

deck (commonly referred 

to by the proprietary name 

“Tectum”).
MAKING SCHOOLS SAFE AGAINST WINDS 6-93

Weak non-load bearing masonry walls, poorly connected 

precast concrete panels, long-span structures (e.g., at gyms) 

with limited uplift resistance, and weak glass curtain walls are 

common problems with many older schools. Although the 

technical solutions to these problems are not difficult, the 

cost of the remedial work is normally quite expensive. If remediation funds are not available, it is important to minimize the 

risk of injury and death by evacuating areas that have this type 

of construction when winds above 60 mph are forecast. 

For schools located in wind-borne debris regions, if the exterior 

glazing is not missile-resistant, equipping the openings with shutters is a cost-effective approach to provide protection.

The recommendations given in Section 6.17 are summarized 

in Table 6-4.

Table 6-4: Summation of Remedial Work on Existing Schools

Perform district-wide assessment of all schools Evaluate all hazards. Prioritize the various schools and the work items at each school. 

Life-safety items are first priority; property damage and school interruption are 

second priority. See Section 6.6.1.

Are there weak non-load bearing masonry 

walls, weak curtain walls, poorly connected 

precast concrete panels, or weak long-span roof 

structures?

If strength is inadequate to resist winds that are likely to occur while the school is 

occupied (such as strong thunderstorms), implement remedial work.

Are edge flashings or copings inadequately 

attached?

Face-attach the vertical flanges. See Figure 6-39.

Are rooftop equipment units unanchored or 

poorly anchored?

Add screws or bolts to anchor equipment to curbs. Add cables to secure fan cowlings. 

Add latches to secure equipment access panels. See Section 6.14.

Are roof deck or roof structure connections 

weak?

During planned roof covering replacement, remove roof covering and strengthen 

attachment of deck and/or roof structure. See Section 6.12.

If the school is in a wind-borne debris region, 

does exterior glazing have protection (via 

laminated glass or shutters)? 

Even if the school will not be used as a shelter, equip with shutters to avoid interior 

wind and water damage. For more conservative protection, consider the wind-borne 

debris region to include areas where the basic wind speed is equal to or greater to 

110 mph (100 mph if the school is located within 1 mile of the coast).

Will the school be used as a hurricane evacuation 

shelter and/or for emergency response after a 

storm?

To the extent reasonably possible, upgrade the school so that it complies with the 

provisions in Section 6.15.

Is the school located in a tornado-prone area? See Section 6.16.
6-94 MAKING SCHOOLS SAFE AGAINST WINDS 

6.18 REFERENCES AND SOURCES OF 

ADDITIONAL INFORMATION 

American Institute of Architects, Buildings at Risk: Wind Design 

Basics for Practicing Architects, 1997. 

Federal Emergency Management Agency, Building Performance: 

Hurricane Andrew in Florida, FEMA FIA-22, Washington, DC, 

December 1992.

Federal Emergency Management Agency, Building Performance: Hurricane Iniki in Hawaii, FEMA FIA-23, Washington, DC, January 1993.

Federal Emergency Management Agency, Corrosion Protection for 

Metal Connectors in Coastal Areas, FEMA Technical Bulletin 8-96, 

Washington, DC, August 1996.

Federal Emergency Management Agency, Typhoon Paka: 

Observations and Recommendations on Building Performance and 

Electrical Power Distribution System, Guam, U.S.A., FEMA-1193-DRGU, Washington, DC, March 1998.

Federal Emergency Management Agency, Hurricane Georges in 

Puerto Rico, FEMA 339, Washington, DC, March 1999.

Federal Emergency Management Agency, Oklahoma and Kansas 

Midwest Tornadoes of May 3, 1999, FEMA 342, Washington, DC, 

October 1999.

Federal Emergency Management Agency, Coastal Construction 

Manual, Third Edition, FEMA 55, Washington, DC, 2000.

Federal Emergency Management Agency, Design and Construction 

Guidance for Community Shelters, FEMA 361, Washington, DC, July 

2000.

Federal Emergency Management Agency, Primer to Design Safe 

School Projects in Case of Terrorist Attacks, FEMA 428, Washington, 

DC, October 2003.
MAKING SCHOOLS SAFE AGAINST WINDS 6-95

Federal Emergency Management Agency, Tornado Protection, 

Selecting Safe Areas in Buildings, FEMA 431, Washington, DC, October 2003.

National Research Council of Canada, Institute for Research in 

Construction, Wind Design Guide for Mechanically Attached Flexible 

Membrane Roofs, B1049, 2004.

Rousseau, M.Z., Facts and Fictions of Rain-Screen Walls, Construction Canada, 1990, pp. 40.

Smith, Thomas L., “Insights on Metal Roof Performance in 

High-wind Regions,” Professional Roofing, February 1995, pp. 12 

(available on-line at www.nrca.net).

Smith, Thomas L., “Integrating a Lightning Protection System in 

a Roof System,” 12th International Roofing and Waterproofing 

Conference Proceedings (CD), National Roofing Contractors Association, 2002.

Smith, Thomas L., “Honing in on hangars,” Professional Roofing, 

October 2002, pp. 32 (available on-line at www.nrca.net).

Smith, Thomas L., “Uplift Resistance of Existing Roof Decks: 

Recommendations for Enhanced Attachment During Reroofing 

Work,” RCI Interface, January 2003, pp. 14.

Smith, Thomas L., “Detailing ASCE 7’s changes,” Professional 

Roofing, July 2003, pp. 26 (available on-line at www.nrca.net).
6-96 MAKING SCHOOLS SAFE AGAINST WINDS 

6.19 GLOSSARY OF WIND TERMS

Basic wind speed. A 3-second gust speed at 33 feet above the 

ground in Exposure C. (Exposure C is flat open terrain with 

scattered obstructions having heights generally less than 30 

feet.) Note: Since 1995, ASCE 7 has used a 3-second peak gust 

measuring time. A 3-second peak gust is the maximum instantaneous speed with a duration of approximately 3 seconds. 

A 3-second peak gust speed could be associated with a given 

windstorm (e.g., a particular storm could have a 40-mile per 

hour peak gust speed), or a 3-second peak gust speed could be 

associated with a design-level event (e.g., the basic wind speed 

prescribed in ASCE 7).

Building, enclosed. A building that does not comply with the requirements for open or partially enclosed buildings.

Building, open. A building having each wall at least 80 percent 

open. This condition is expressed by an equation in ASCE 7.

Building, partially enclosed. A building that complies with both of 

the following conditions:

1. The total area of openings in a wall that receives positive 

external pressure exceeds the sum of the areas of openings in 

the balance of the building envelope (walls and roof) by more 

than 10 percent, and 

2. The total area of openings in a wall that receives positive 

external pressure exceeds 4 square feet or 1 percent of the 

area of that wall, whichever is smaller, and the percentage of 

openings in the balance of the building envelope does not 

exceed 20 percent.

These conditions are expressed by equations in ASCE 7.

Building, regular shaped. A building having no unusual geometrical irregularity in spatial form.
MAKING SCHOOLS SAFE AGAINST WINDS 6-97

Building, simple diaphragm. An enclosed or partially enclosed 

building in which wind loads are transmitted through floor and 

roof diaphragms to the vertical main wind-force resisting system.

Components and cladding. Elements of the building envelope that 

do not qualify as part of the main wind-force resisting system.

Escarpment. Also known as a scarp, with respect to topographic effects, a cliff or steep slope generally separating two levels or gently 

sloping areas. 

Exposure. The characteristics of the ground roughness and surface irregularities in the vicinity of a building. ASCE 7 defines 

three exposure categories - Exposures B, C, and D. 

Glazing. Glass or transparent or translucent plastic sheet used in 

windows, doors, and skylights.

Glazing, impact-resistant. Glazing that has been shown by an 

approved test method to withstand the impact of wind-borne 

missiles likely to be generated in wind-borne debris regions 

during design winds.

Hill. With respect to topographic effects, a land surface characterized by strong relief in any horizontal direction.

Hurricane-prone regions. Areas vulnerable to hurricanes; in the 

U.S. and its territories defined as:

1. The U.S. Atlantic Ocean and Gulf of Mexico coasts where the 

basic wind speed is greater than 90 miles per hour, and

2. Hawaii, Puerto Rico, Guam, U.S. Virgin Islands, and American 

Samoa.

Impact-resistant covering. A covering designed to protect glazing, 

which has been shown by an approved test method to withstand 

the impact of wind-borne missiles likely to be generated in windborne debris regions during design winds.
6-98 MAKING SCHOOLS SAFE AGAINST WINDS

Importance factor, I. A factor that accounts for the degree of 

hazard to human life and damage to property. The importance 

factor adjusts the mean recurrence interval. Importance factors 

are given in ASCE 7.

Main wind-force resisting system. An assemblage of structural 

elements assigned to provide support and stability for the overall 

structure. The system generally receives wind loading from more 

than one surface.

Mean roof height, h. The average of the roof eave height and the 

height to the highest point on the roof surface, except that, for 

roof angles of less than or equal to 10 degrees, the mean roof 

height shall be the roof eave height.

Missiles. Debris that became or could become ingested into the 

wind stream. 

Openings. Apertures or holes in the building envelope that allow 

air to flow through the building envelope and that are designed 

as “open” during design winds. A door that is intended to be in 

the closed position during a windstorm would not be considered 

an opening. Glazed openings are also not typically considered an 

opening. However, if the building is located in a wind-borne debris 

region and the glazing is not impact-resistant or protected with an 

impact-resistant covering, the glazing is considered an opening.

Ridge. With respect to topographic effects, an elongated crest of a 

hill characterized by strong relief in two directions.

Wind-borne debris regions. Areas within hurricane-prone regions 

located:

1. Within 1 mile of the coastal mean high water line where the 

basic wind speed is equal to or greater than 110 mph and in 

Hawaii; or

2. In areas where the basic wind speed is equal to or greater than 

120 mph.
ACRONYMS A

ACRONYMS A-1

A

AASHTO American Association of State Highway and 

 Transportation Officials

ACSA Association of Collegiate Schools of 

 Architecture

ADA Americans with Disabilities Act

AHJ Authority Having Jurisdiction

AIA American Institute of Architects

AK Alaska

AL Alabama

ANSI American National Standards Institute

ARC American Red Cross

ASCE American Society of Civil Engineers

ASTM American Society for Testing and Materials

ATC Applied Technology Council

B

BFE base flood elevation

BOCA Building Officials and Code Administrators 

 International

BSSC Building Seismic Safety Council

BUR built-up roof
A-2 ACRONYMS 

C

CA California

CBR chemical, biological, or radiological

CMU concrete masonry unit

D

DE Delaware

DFE design flood elevation

E

EIFS exterior insulation finish system

ELF Equivalent Lateral Force

EPDM ethylene propylene diene monomer

EPS expanded polystyrene system

F

FEA finite element analysis

FEMA Federal Emergency Management Agency

FIRM Flood Insurance Rate Map

FIS Flood Insurance Study

FL Florida

FM Factory Mutual

FMG Factory Mutual Global

FMR Factory Mutual Research
ACRONYMS A-3

G

GIS Geographic Information System

gpm gallons per minute

H

HazMat hazardous materials

HAZUS Hazards U.S.

HAZUS-MH Hazards U.S. - Multihazards

HID high intensity

HVAC heating, ventilating, and air conditioning

I

IBC International Building Code

ICBO International Conference of Building Officials

ICC International Code Council

ID identification

IL Illinois

IT Information Technology

K

K-12 kindergarten to grade 12

km kilometer
A-4 ACRONYMS 

L

LA Louisiana

LCD liquid crystal display

M

MA Massachusetts

MD Maryland

M/E/P Mechanical/Electrical/Plumbing

mph miles per hour

MT Montana

MWFRS main wind-force resisting system

N

NBC National Building Code

NC North Carolina

NEHRP National Earthquake Hazards Reduction Program

NFIP National Flood Insurance Program

NFPA National Fire Protection Association

NIBS National Institute of Building Sciences

O

O&M operations and maintenance

OH Ohio

OSB oriented strand board
ACRONYMS A-5

P

PA Pennsylvania

PMR protected membrane roof

psf pounds per square foot

R

RC reinforced concrete

RSP Rapid Screening Procedure

S

SBC Standard Building Code

SBCCI Southern Building Code Congress International

SC South Carolina

SEACO Structural Engineers Association of California

SFPE Society of Fire Protection Engineers

SPF sprayed polyurethane foam

SUG Seismic Use Group

T

TN Tennessee

tv television

TX Texas
A-6 ACRONYMS

U

UBC Uniform Building Code

URM unreinforced masonry

U.S. United States

USACE U.S. Army Corps of Engineers

USFA United States Fire Administration

USGS United States Geological Survey

UT Utah

V

VA Virginia

W

W Washington