Safe Rooms: General Information on In Home Shelter
Taking Shelter From The Storm
Every year, tornadoes, hurricanes and other extreme windstorms injure and kill
hundreds of people, and damage millions of dollars worth of property in the
United States. Even so, more and more people build houses in tornado- and
hurricane-prone areas, possibly putting themselves into the path of such
storms.
Having a shelter, or a safe room, built into your house can help you protect
yourself and your family from injury or death caused by the dangerous forces of
extreme winds. It can also relieve some of the anxiety created by the threat of
an oncoming tornado or hurricane.
If you live in a hurricane evacuation area, or a mobile home anywhere in
Escambia County, you should evacuate when instructed by local officials. If you
do not live in one of these, you should consider building a safe room,
protecting windows and doors, and remaining at home during a hurricane.
Basis of Shelter Design
The purpose of a shelter is to provide a space where you and your family can
survive a tornado or hurricane with little or no injury. In hurricane-prone
areas, the shelter cannot be built where it can be flooded during a hurricane.
Your shelter should be readily accessible from all parts of your house, and it
should be free of clutter. To protect the occupants during extreme windstorms,
the shelter must be adequately anchored to the house foundation to resist
overturning and uplift. The connections between all parts of the shelter must
be strong enough to resist failure, and the walls, roof, and door must resist
penetration by windborne missiles.
Extensive testing by Texas Tech University and other wind engineering research
facilities has shown that walls, ceilings, and doors commonly used in house
construction cannot withstand the impact of missiles carried by extreme winds.
Texas Tech University, after years of extensive testing, has developed plans
for shelters or "safe rooms" that will resist penetration by missiles in
extreme winds that are rarely exceeded in the United States (winds of up to 250
miles per hour and the impact of a 15 pound 2 X 4, shot from a cannon at 100
miles per hour).
These shelter plans can be obtained, free of charge, by calling the Federal
Emergency Management Agency (FEMA) toll free at 1-888-565-3896 and requesting
FEMA Publication 320. You can also download the publication from FEMA's website
at www.fema.gov/mit/saferoom. While the booklet was developed primarily for use
in new construction, some of the plans can be used for "retrofit" in existing
homes. The term "retrofit" refers to the process of making changes to an
existing home. Modifying the walls or foundation of an existing house as
necessary for the construction of a safe room is more difficult and more
expensive. There are also a few companies that market "retrofit" kits for safe
rooms that have been tested and certified by Texas Tech University.
Therefore, a shelter built according to these design standards is expected to
withstand the forces imposed on it by extreme winds without failing. Those
forces may cause cracks or other signs of stress in the materials or
connections used in the shelter, and the may cause materials or connections to
yield. However, the intent of the design is not to produce a shelter that will
always remain completely undamaged, but rather a shelter that will enable its
occupants to survive an extreme windstorm with little or no injury.
Shelter Size
The amount of floor area per person that your shelter must provide depends
partly on the type of windstorm the shelter is intended to protect you from.
Tornadoes are not long lasting storms, so if you are relying on your shelter
only for tornado protection, you will not need to stay in the shelter for a
long time. As a result, comfort is not of great concern, and a shelter that
provides about 5 square feet of floor area per person will be big enough.
When the shelter is intended to provide protection from storms such as
hurricanes, which can last up to 12 hours, the comfort of the occupants should
be considered. For this type of shelter, the recommended amount of floor area
per person is about 10 square feet. Necessities, such as water and toilet
facilities, should be provided. The largest shelter design provided in the
booklet is 8 feet by 8 feet. A shelter of that size used for hurricane
protection can accommodate up to six people in reasonable comfort. If you plan
to build a shelter with any wall longer than 8 feet, consult a licensed
professional engineer or architect.
Shelter Location
There are several possible locations in your house for a shelter. Perhaps the
most convenient, safest and least expensive is below ground level, in a
basement. Since most houses in this area do not have a basement, you can
install an in-ground shelter beneath a concrete slab-on-grade foundation or a
concrete garage floor. Inground shelters provide the highest level of
protection against missiles and falling debris. In ground shelters will be
subject to flooding and should not be installed in areas known to flood during
heavy rains or where the water table is high.
Another alternative location, and probably the most practical in this area, is
an interior room on the first floor of the house. Researchers, emergency
response personnel, and people cleaning up after tornadoes have often found an
interior room of a house still standing when all other above ground parts of
the house have been destroyed. Closets, bathrooms, and small storage rooms
offer the advantage of having a function other than providing occasional storm
protection. Typically these rooms have only one door and no windows, which
makes them well suited for conversion to a shelter. Bathrooms have the added
advantage of including a water supply and toilet.
Regardless of where in your house you build your shelter, the walls and ceiling
of the shelter must be built so that they will protect you from missiles and
falling debris, and so that they will remain standing if your house is severely
damaged by extreme winds. If sections of your house walls are used as shelter
walls, those sections must be separated from the structure of the house. This
is true regardless of whether you use interior or exterior walls of the house.
Any space that is to be used for a shelter must be kept free of clutter so that
the shelter can be quickly and easily entered and so that the shelter occupants
will not be injured by falling objects. For this reason, a bathroom is often a
better choice for a shelter than a closet or other space used for storage. This
is especially true for tornadoes, when little warning is given. For hurricanes
however, there is plenty of warning to prepare the shelter for use.
Regardless of where the shelter is built, it must be equipped with a door that
will resist the impact of missiles.
Shelter Materials
Based on the plans in FEMA Publication 320, the materials your
builder/contractor will need to build your shelter should be available from
building material suppliers in this community. These materials have been
carefully selected for their strength, durability, and/or ability to be readily
combined in ways that enable them to withstand the forces of extreme winds and
the impact of windborne missiles. Your builder/contractor should not substitute
any other material for those specified in the designs.
One of the most vulnerable parts of your shelter is the door. The materials
specified for doors in the booklet shelter designs, were tested by the Wind
Engineering Research Center at Texas Tech University for their ability to carry
wind loads and prevent penetration by windborne missiles. The Installation of
the door is as important as the materials used in the construction. Please
confirm with your builder/contractor that the door to your shelter can be
installed the way it is shown in the design plans.
Shelter Cost
The cost of your shelter will vary according to the following:
-
the size of the shelter
-
the location of the shelter
-
the number of exterior house walls used in the construction of the shelter
-
the type of door used
-
the type of foundation on which your house is built
-
your geographic location (material costs vary in different regions of the
country)
-
whether you are building a shelter into a new house or retrofitting an existing
one
In general, the cost of building your safe room may vary from $3,000 if you are
building a new house to $4,500 or higher if you are retrofitting an existing
house. It is an investment that should be considered to ensure your family's
safety.