Tornado Protection: Selecting Refuge Areas in Buildings 
FEMA 431

November 2003

FEMA


About the Cover 

The large photograph on the cover shows the remains of a central corridor in the Kelly 
Elementary School, in Moore, Oklahoma. This extensive damage was caused by one 
of the tornadoes that struck Oklahoma and Kansas on May 3, 1999. The corridor walls, 
which consisted of lightweight steel frame members with masonry infill topped by 
clerestory windows, were unable to withstand the extreme loads caused by lateral and 
uplift wind forces. As indicated by the inset photograph, which shows a similar corridor 
in another school, this type of corridor construction is common and creates special 
challenges for building administrators and design professionals who must identify 
refuge areas in schools and other buildings. 
Contents



Foreword iii


Introduction  v


Chapter 1: Tornado Profile 1


Chapter 2: Effects of High Winds 7

 Wind Effects on Buildings  7

 Atmospheric Pressure Changes 8

 Debris Impact 9

 Selecting Refuge Areas 10


Chapter 3: Case Studies 11

 Xenia Senior High School 13

 St. Augustine Elementary School and Gymnasium 21

 St. Augustine Elementary School Building 22

 St. Augustine Elementary School Gymnasium  25

 Kelly Elementary School 27


Chapter 4: Selection Procedure  37

 Determine the Required Amount of Refuge Area 38

 Review Construction Drawings and Inspect the Building  39

 Assess the Site 42

 Example of Refuge Area Selection Process 44

 General 44

 Required Refuge Area Space  46

 Architectural and Structural Characteristics  46

 Identifying the Best Available Refuge Areas 51

 Verifying the Best Available Refuge Areas 54

 Selecting the Best Available Refuge Areas in
 Other Types of Buildings  55

 Mid-Rise and High-Rise Buildings 55

 Large Stores and Movie Theaters 55


Chapter 5: Conclusions 57

Information Sources  61





Foreword

Tornadoes cause heavy loss of life and property damage throughout much of the 
United States. Most schools and other public buildings include areas that offer some 
protection from this danger, and building administrators should know the locations of 
these areas. 

This booklet presents case studies of three schools that were struck by tornadoes: 
Xenia Senior High School in Xenia, Ohio; St. Augustine Elementary School in 
Kalamazoo, Michigan; and Kelly Elementary School in Moore, Oklahoma, which 
were struck on April 3, 1974; May 13, 1980; and May 3, 1999, respectively. The 
resulting damage to these schools was examined by teams of structural engineers, 
building scientists, engineering and architectural faculties, building administrators, and 
representatives of the architectural firms that designed the buildings. From these and 
other examinations, guidance has been developed for selecting the safest areas in 
existing buildings - areas that may offer protection if a tornado strikes - referred to in 
this booklet as the best available refuge areas. 

The guidance presented in this booklet is intended primarily to help building 
administrators, architects, and engineers select the best available refuge areas in 
existing schools. Building administrators, architects, and engineers are encouraged to 
apply this guidance so that the number of injuries and deaths will be minimized if a 
tornado strikes an occupied school. 
For the design of shelters in schools yet to be constructed, refer to FEMA publication 
361, Design and Construction of Community Shelters. 




Introduction

What Are "Best Available Refuge Areas"? 

The term best available refuge areas refers to areas in an existing building that have 
been deemed by a qualified architect or engineer to likely offer the greatest safety for 
building occupants during a tornado. It is important to note that, because these areas 
were not specifically designed as tornado shelters, their occupants may be injured or 
killed during a tornado. However, people in the best available refuge areas are less 
likely to be injured or killed than people in other areas of a building. 
The likelihood that a tornado will strike a building is a matter of probability. Tornado 
damage to buildings is predictable. Administrators of schools and other public buildings 
should have a risk analysis performed to determine the likelihood that a tornado will 
occur and the potential severity of the event. If a building is determined to be at 
sufficient risk, the safest areas of the building - areas that may offer protection if a 
tornado strikes - should be identified. This booklet refers to such areas as the best 
available refuge areas. In many buildings, the best available refuge areas are large 
enough to accommodate the number of people who normally occupy the building. A 
qualified architect or structural engineer should assess an existing building and identify 
the best available refuge areas. 

This booklet presents information that will aid qualified architects and engineers in the 
identification of the best available refuge areas in existing buildings. Architects and 
engineers who are designing tornado shelters within new buildings may also find this 
booklet useful, but should refer to Design and Construction Guidance for Community 
Shelters(FEMA 361) for more detailed information. FEMA 361 includes design 
criteria, information about the performance of specific construction materials under 
wind and debris impact loads, and examples of construction plans and costs. 
The Wind Engineering Research Center at Texas Tech University provided much of 
the substance of this booklet. Dr. Kishor Mehta of the Center assisted in the preparation 
and review of the material. Invaluable assistance was provided by the architects and 
engineers of the buildings presented as case studies and by the school administrators.