What to Look for When Researching an Above-Ground Tornado Shelter

Investing in a tornado shelter is a significant decision. You are not merely making a large purchase; you are relying on this structure to protect your family during severe weather events. Therefore, understanding what to look for and selecting the right tornado shelter is essential.

While almost all tornado shelters are FEMA EF5 rated, they are not all constructed equally. Below is a comprehensive guide on what to evaluate when considering an above-ground shelter. This list is intended to help you gauge the structural integrity of your shelter and understand the forces it can withstand.

The Importance of Proper Anchoring

The most critical factor in an above-ground shelter is how it is anchored to your concrete foundation. Powerful tornadoes generate massive uplift forces. The inherent strength of your shelter becomes irrelevant if it disconnects from the concrete and is lifted off the ground.

When evaluating a shelter, take a close look at the hardware used for installation and consider the following:

• Hardware Quantity: The number of bolts, wedges, or anchors connecting the shelter to the concrete.
• Anchor Depth: The depth to which this hardware penetrates the concrete (e.g., 4-inch, 5-inch, or deeper anchors).
• Hardware Diameter: The thickness of the hardware used (e.g., 3/8-inch, 1/2-inch, or 3/4-inch).

A shelter that is correctly mounted will be capable of surviving the impact of a car crashing into it. Conversely, an incorrectly mounted shelter can easily disconnect from the concrete following any significant impact. For visual reference on the importance of proper anchoring, you can view storm shelter impact tests below:

• Storm Shelter Impact Test – Video 1
• Storm Shelter Impact Test – Video 2

Essential Structural Features

After verifying how the shelter is secured to the ground, examine the following essential elements to ensure maximum protection:

1. Material Quality and Thickness

Ensure the shelter is constructed from real steel. Generally, the thicker the steel, the better the protection. Cold-rolled steel is highly preferable, as it can be up to 20% stronger than standard hot-rolled steel.

2. Construction Method: Welded vs. Bolted

Welded shelters offer superior strength compared to those that are bolted together. However, if you opt for a bolted shelter, closely inspect the size and quality of the connecting bolts. It is also important to note that bolts require periodic checking and tightening to maintain structural integrity.

3. The Necessity of a Full Floor

It is vital to ensure your shelter features a full steel floor. Many storm shelters only provide a bottom lip around the edge, which is where the hardware connects to the concrete. To achieve full structural integrity and rigidity, the shelter must be a complete, six-sided cube.

An easy way to understand the importance of a floor is to imagine squeezing a paper coffee cup with and without a lid. The cup with the lid holds its shape while squeezed. Tornado shelters without a floor are like a cup without a lid — they are much more prone to detaching from the concrete, denting, or crushing under pressure.

4. Electrical Protection

In addition to providing structural strength, a full floor helps protect the shelter’s occupants from electrocution. A complete floor allows the shelter to act as a Faraday cage. In the event of downed power lines or lightning strikes, electricity tends to flow around the shelter’s outer shell before safely grounding, rather than passing through the interior.

5. Corner Reinforcements

Look for dedicated reinforcements in the corners of the shelter. Instead of relying solely on the strength of the welds or bolts where the panels meet, high-quality shelters feature additional reinforcements on both the inside and outside of the corners.

6. Internal Wall Reinforcements

High-quality shelters incorporate steel “C” channels inside the structure to add significant strength. This is similar to the studs inside a home’s walls or the bones in an animal. The highest quality shelters feature these channels running both vertically and horizontally, creating strength in all directions. During a real tornado, shelters undergo impacts from multiple angles, and these internal reinforcements ensure the structure remains intact.

7. Adequate Ventilation

Ensure your shelter has proper ventilation. For effective airflow, the shelter should feature at least two distinct vents.

8. Door Security and Design

The shelter door must be secured with large steel pins capable of withstanding severe impacts. Ideally, the slots for these pins should be oversized to allow additional room for the door to slide or shift in the event it takes a direct impact. Furthermore, always ensure the door opens inward — an outward-opening door can easily become blocked by debris, trapping occupants inside.

9. Reliable Access Mechanisms

Make sure you can easily and reliably access your shelter through the door. It is best to avoid keypad entries, as these can run out of battery power or eventually suffer from mechanical failure when you need them most.

10. Manufacturer Reputation and Certification

Always verify that the company manufacturing the shelter is reputable. Authentic shelters are produced by established companies, third-party tested by institutions such as Texas Tech University, and subsequently certified by FEMA, ICC 500, and the ATSA. If a shelter lacks these certifications, proceed with caution.

Following nearby tornadoes, individuals with at-home welding equipment frequently begin selling unverified shelters. These structures are usually untested, and the individuals producing them often appear and disappear with every tornado season.

Conclusion

If a shelter meets all of these stringent standards, it is essentially a bank vault. Above-ground shelters absolutely can be safe options for your family, even during extreme EF4 and EF5 tornadoes. The key lies in who manufactures your shelter, how it is constructed, and how securely it is anchored.

At Valley Storm Shelters, these critical features are standard in every shelter we build. We never want your family to have to wonder whether your shelter will perform when it matters most. We provide extensive video documentation on our website and YouTube channel to show you exactly how our shelters are designed, built, installed, and rigorously tested.

We hope this comprehensive guide has been helpful in your research for an above-ground tornado shelter. Follow us for more articles and essential information regarding tornado safety.

Sincerely,
Valley Storm Shelters