Traditional storm shelters are installed below ground. The earth itself provides
protection from high winds and flying debris. When an in-ground shelter isn’t practical, a well-engineered above-ground shelter can provide equal protection.
When shopping for an above-ground storm shelter, be sure to consider the following seven critically important features.
1. Wind Resistance
The strongest wind speed ever recorded for a tornado was over 300 miles per hour. Your storm shelter should be engineered to withstand similar wind speeds.
Pay special attention to the method of anchoring the shelter to the ground. The best shelters use expanding bolts to anchor the shelter to a reinforced concrete slab.
2. Impact Resistance
The majority of tornado injuries and deaths are caused by windborne debris. When tossed by a tornado, a piece of lumber can easily go through a concrete block wall.
Standards for impact damage testing and certification are currently evolving. Current guidelines include Federal Emergency Management Agency (FEMA) P-361: Safe Rooms for Tornadoes and Hurricanes: Guidance for Community and Residential Safe Rooms and International Code Council (ICC) 500-2008: Standard for the Design and Construction of Storm Shelters.
Impact testing has been performed in the past by the National Wind Institute (NWI) Debris Impact Facility (DIF) at Texas Tech University and is currently being done by Intertek and Underwriter’s Laboratory (UL).
3. Crush Resistance
Tornadoes often topple trees and demolish houses. The stronger ones can toss cars and other heavy objects hundreds of feet. Your storm shelter must be able to protect you from being crushed as well as from flying debris.
Ask for proof that the shelter has been tested for crush resistance.
Here is an interesting video of a car being dropped from 60 feet onto an Atlas Safe Room storm shelter: https://youtu.be/8NpXqU3z2pw
4. Air Circulation
Although a tornado is over in minutes, you could be trapped for hours. It is critical that your shelter has good fresh air circulation, even if some vents are blocked by debris.
5. Modular Design
Many above-ground storm shelters are built as a single unit, requiring a truck and loader (or possibly a crane) for delivery and installation. These shelters can usually only be installed when a house is being built, unless it is placed outside or in a garage.
Modular storm shelters are assembled from structural panels and components. They are as strong as single-unit shelters, but can be installed indoors or in a basement.
6. Multiple Exits
If the storm shelter has a door that opens outwards, you could be trapped until someone digs you out. If the door swings in, you have a much better chance of getting out.
Modular design shelters may have an advantage, if panels can be unbolted from within to provide an alternative exit.
7. Locking Mechanism
The door must be secured from within the shelter and easily opened even after a disaster. The locking mechanism must be able to withstand the same stresses as the rest of the shelter.
The best locking mechanisms use multiple steel pins to lock the door in place and withstand direct impacts of windborne debris.
You may intend to store valuables in your shelter (perhaps important papers or precious metals). If so, your shelter probably needs a keyed lock to prevent theft. Just make sure it doesn’t keep you locked out in an emergency.
And, if you want to use your storm shelter as a safe room, you will need a way to lock it (like a keyed lock) from the inside.
Regardless of the “bells and whistles” advertised by a storm shelter manufacturer, pay close attention to these seven features. In an emergency, any one of them could make a life or death difference.
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