Effective tornado-proof houses and rooms: can they be built?

May 29

Terry Moore shows her granddaughter, Jayzlei Blackwell, 4, the newly installed Storm Safe Shelter tornado shelter in the floor of the garage almost one year after a tornado on May 19, 2014 in Moore, Oklahoma. Barry Stephenson, the Vice President of Storm Safe Shelters, said they put in about 25 shelters a day for home owners. On May 20, 2013 a two-mile wide EF5 tornado touched down in the town killing 24 people and leaving behind extensive damage to homes and businesses. (Photo by Joe Raedle/Getty Images)

In 2011, after a particularly violent tornado touched down in the unlikely vicinity of Springfield, Massachusetts, I explored whether it was possible to build a tornado-proof home.

At the time. claims were made about the exceptional durability and even invincibility of certain construction methods, such as: ICFs (insulating concrete LEGO®-like forms composed of 5-inch thick styrofoam building blocks filled with 8 inches of steel-reinforced, floor-to-ceiling concrete); and SIPs (structural insulating foam core panels, favored because of their strength, and mold-resistant qualities). Dr. Ernst Kiesling, Executive Director of the National Storm Shelter Association (NSSA), believed they held great promise but “greatly increased building cost,” and required the house to be basically “missile resistant.”

Of greater potential, according to Stan Peterson, a member of the American Institute of Architecture Disaster Assistance Task Force, was to build a “safe room,” a hardened interior structure, converted from, say, a bathroom or closet, which could be built for under $2000. Kiesling, of NSSA, agreed, although he now says that a strong, reinforced, barrier-door alone might cost up to $2000.

“Safe” room fatality

As Jason Samenow pointed out in his April 22 post, the 2014 tornado season had an unusually sluggish start, probably due in part to the late spring in many parts of the country. But the April 28 EF-4 twister, which devastated a 41-mile swath in central Arkansas, abruptly changed all of that. It also gave pause to review the standards by which so-called “safe” rooms are constructed because, apparently for the first time (that I know of), someone died from a tornado’s direct hit while seeking shelter in a safe room.

As it turns out, the Federal Emergency Management Agency (FEMA) has published very strict guidelines for building a safe room in its brochure: FEMA P-320, Taking Shelter from the Storm: Building a Safe Room for Your Home or Small Business (third edition, 2008a).

But was it really a “safe” room?

The answer is “apparently not,” for several reasons, the most important of which is that the room wasn’t designed or constructed according to FEMA guidelines. This is known because, according to Dr. Kiesling, neither a permit nor any of the other construction requirements were ever officially registered with the appropriate state and federal agencies. It was actually the husband of the deceased who built the room. (It’s unknown if the woman’s spouse was living at the time and, if so, if he survived elsewhere).

But even if the room had been reasonably well constructed, there are other possible reasons for the woman’s death, because according to Rick Smith of the local National Weather Service office, (1) the door, locks, and hinges may have been insufficient for use on a storm shelter; and (2) it’s possible that the door was not actually shut and locked. (But first responders seem to suggest that the door was at least closed, although only one of 3 dead bolts was engaged, possibly allowing the door to blow open, which caused the woman’s severe head injury.) Obviously, all of this awaits a team of storm shelter experts to provide the best clues as to what really happened.

By the way, it bears repeating (from the earlier post) that even the relatively small expense of a safe room might seem unnecessary to some, as statistics have shown that even in tornado alley, the chances of a particular home being struck by a tornado during its rated life span of 50 years is only about 1%. On the other hand, keep in mind that if you are in that 1%, the destructive force of a 150 mph wind is not 3 times that of a 50 mph wind—it’s more like 9 times!

And in case you’re wondering, the Texas Tech Wind Science and Engineering Research Center has grave misgivings about remote underground shelters—even though they’re in considerable use–because people tend to wait until the last possible minute before taking refuge, thereby subjecting themselves to flying debris, etc.)

For more information about safe rooms, other kinds of tornado shelters, and tornado information in general, please visit the Storm Prediction Center’s (SPC) tornado FAQ page from NOAA.

You can view a partially deconstructed FEMA-specified safe room built to withstand violent tornadic winds to over 250 mph at the National Building Museum’s innovative exhibit “Designing for Disaster.”

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Brendan Richardson · May 29