Every year, an average of 1,000 tornadoes are reported in the U.S., causing 80 deaths and 1,500 injuries. Being in the path of Tornado Alley, Oklahoma is a prime target. Since 1893, 23 tornados have hit Moore, Okla., and surrounding neighborhoods alone, killing 100-plus people. But residential tornado shelters are still more of an exception than a rule in the Sooner State.

This year’s round of tornadoes, which caused at least $2 billion in property damage, would seem the perfect catalyst for changing Oklahomans’ minds in favor of installing shelters into existing homes or ordering them with new builds. And hints of pent-up demand are becoming more evident. “I’m swamped for the next five months,” said Robert Webb, owner of Oklahoma City–based shelter supplier ArmourVault, after the Moore weather event.

In late May, Darla Cheek, marketing and communications director for the Oklahoma City Metropolitan Association of Realtors, found herself No. 541 on a waiting list to have a shelter installed in her home at Winfield, a subdivision on the edge of Moore.

But homeowner demand for shelters rarely extends beyond storm season in early spring. “I would not say we push them,” says Anita Brown, director of marketing for Home Creations, a production builder in Moore that offers tornado shelters as options in its new homes. “We make them available; it’s a personal choice.”

Widespread acceptance of shelters is unlikely unless suppliers and builders can crack Oklahomans’ resistance to spending money on something that, in their minds, they might never need. And as long as shelters are optional in new-home purchases, “hardwood floors and granite countertops just win out,” says Steve Shoemaker, director of marketing for Norman, Okla.–based Ideal Homes, which included shelters in about 24 of the 306 homes it closed in Oklahoma City last year.

Shelters: Why do I need One?

Tornado shelters are a hard sell because, just like Californians and earthquakes, Oklahomans always expect tornadoes to smash someone else’s house.

“The probability of being affected by a tornado is still pretty small,” observes Ernst Kiesling, executive director of the National Storm Shelter Association (NSSA) in Lubbock, Texas. As hard as it is to believe, some Oklahomans have never actually seen a tornado firsthand.

In fact, Lloyd’s of London puts the odds of a structure in Tornado Alley ever taking a direct hit from a tornado at 5,000 to 1.

Violent tornadoes accounted for less than one-tenth of 1 percent of all tornadoes recorded, and less than one-quarter of those tornadoes generated wind speeds above 110 mph.

“We have had so many storms over the years that people almost become resigned,” says local builder Caleb McCaleb. That said, the majority of McCaleb Homes’ customers order tornado shelters with their new-home purchases. McCaleb acknowledges that his clientele is more affluent than typical buyers here. But he’s never understood why any person who readily shells out $25,000 for a pickup truck will balk reflexively at spending $3,000 for an underground storm shelter. (Factory-built safe rooms cost about $2,500 to $6,000, according to manufacturers.)

That attitude might change if shelters and safe rooms enhanced property value. “We have appraisal issues down here, so I doubt any appraiser would give you [credit] for a shelter right now,” says Robert Crout, a land developer and current president of the Central Oklahoma HBA.

Appraisers have viewed storm shelters as they would lawn sprinkler systems, says Keith Taggert, president of the Oklahoma City Metropolitan Association of Realtors: something that people like to have but won’t pay full value for at resale. Although that could change, says Taggert, who recently talked with an appraiser who gives credit to shelters in his evaluations in the wake of the storm.

Mandates: builders Say NO

Property value is really beside the point, as shelters protect people, not structures. And no one disputes the unassailable logic that tornado shelters provide homeowners with greater safety. Chris Ramseyer, an associate professor of civil engineering and environmental science at the University of Oklahoma, tells BUILDER that several of the houses he inspected after the Moore tornado looked like “porcupines,” with shards of wood sticking out of exteriors they penetrated.

The lethal potential of tornadoes to kill people trapped inside of houses has led Ramseyer to conclude that shelters should be mandatory in areas susceptible to annual tornadoes. Moore Mayor Glenn Lewis agrees, and he recently proposed an ordinance that would require shelters in all new single- and multifamily construction.

However, the state’s governor, Mary Fallin, opposes them—and so do local builders and their trade associations.

NSSA’s Kiesling, also a civil engineering professor at Texas Tech University, is concerned less about mandates than with what he says are unfounded assertions by builders, architects, and other “experts” that in-ground shelters are safer than aboveground safe rooms. “There are standards from the national code council and FEMA … for building safe rooms where occupants will be safe. And it’s hard to make an in-ground shelter ADA-compliant,” he says, referring to the Americans with Disabilities Act.

Local observers point out that many of the destroyed Moore homes predated the 2009 International Residential Code (IRC), which Oklahoma adopted as its first statewide building code two years ago. That code requires resistance to 90 mph wind loads at a 3-second burst 33 feet above the ground. (The 2012 code, which the state is reviewing, requires resistance up to 120 mph.)

It is not known how many of Oklahoma’s 77 counties comply with the state code, primarily because the Oklahoma Uniform Building Code Commission doesn’t have enforcement power, according to its administrator Mary Oberly.

Tornado proof: is it possible?

The majority of Oklahomans never encounter a tornado. While tornadoes are violent and the big ones make headlines, they are not all that common and they affect only a small area. You can buy a lot of insurance for what it costs to fortify a home to withstand even a small tornado.

Still, some Tornado Alley homeowners go beyond code and add a safe room or storm shelter. According to Curtis McCarty, a builder of wind-resistant homes in Oklahoma, what has been learned about building homes in hurricane areas may not work in tornado-prone regions.

“A tornado is very different than a hurricane,” McCarty says. “The winds are much stronger and confined to a much more compact area. The winds from a tornado come from all directions in a circular motion in a very short time frame, often seconds, whereas hurricane winds are generally from one direction for an extended period of time.”

The builder says some meteorologists estimate that the winds at the core of an EF5 tornado could top 400 mph. But Kiesling insists that this wind load estimate is a myth when ground-level winds are measured. He adds that the Moore tornado never exceeded 200 mph, so storm shelters—which are designed to withstand winds of 250 mph—should be safe.

Marvin Haworth, president of the Moore Association of Home Builders, concurs with McCarty. “I was here for both the 1999 and 2013 tornadoes,” Haworth says. “While the wind speeds of the 1999 tornado may have been higher, the destruction from the 2013 tornado is much worse. It was a slow-moving storm and just sat in one place for an extended period of time and kept hammering away at structures, chewing up everything in its path.”

While rebuilding homes in Moore after 1999, McCarty began investigating ways to make them stronger. In 2011, several smaller storms caused significant damage in Moore from simple microbursts—short gusts of winds upward of 100 mph. So McCarty put together a program with FEMA, the Oklahoma HBA, Owens Corning, Simpson Strong-Tie, and State Farm Insurance to develop and build the state’s first high-wind-resistant home.

The design ties the roof, walls, and floors to the concrete slab with metal connectors and threaded rod, and the door and window openings are fortified. “After the 1999 Moore tornado, researchers discovered that if we can keep the roof on a house, we can limit damage in many cases,” McCarty explains.

But he adds: “These techniques are designed to make the home wind-resistant up to about an EF3. They are not designed to withstand a direct hit from an EF5. Not much can.”

Jim Gendill, a licensed structural engineer with Anasazi Engineering in Edmond, Okla., agrees. “Not many structures can withstand a direct hit from an EF5 tornado. But 800 feet away from the tornado, many homes are still standing, some with only minor damage.”

For years, Ideal Homes has built with steel connectors and ties, says Todd Booze, the company’s president of construction. He contends that if a house is 50 feet from a tornado, it generally will stay together with ties, connectors, and straps that add about $2,500 to the overall cost of construction.

The question, however, is how much more do you put into the house? “Even if codes called for resistance up to 150 or 160 mph, we’re not going to see that [in Oklahoma] unless we have a severe tornado,” Booze says. “And if you take a direct hit from a tornado, the house will get torn apart.”

Much more common and still very damaging are smaller EF0-EF3 tornados, along with straight line winds of up to 100 mph. Homes reinforced with hurricane clips and roof ties are much more likely to withstand a glancing blow from these more common storms with only minimal damage, lowering both repair and insurance costs.

The builders we spoke with said constructing a home that can withstand a direct hit from an EF5 tornado is doable, but not very practical. “Nobody could afford it,” McCarty says.

Rebuilding: Again and Again

Any discussions about tornado shelters and high-wind resistance homes are relevant only to residents and businesses in the afflicted areas intending to stay and rebuild. Whether they lost electricity or their entire house, some 48,000 Oklahomans were affected by the Moore tornado and the storms that hit the Oklahoma City area again 11 days later. And inevitably, a certain percentage of families—who can’t afford to wait for their houses to be rebuilt—are going to move somewhere else. But if history is any guide, most Oklahomans will hold on and stay.

Crout, the Central Oklahoma HBA president, predicts that homes will be rebuilt, “but not by the people who lived in them. Builders will buy up those lots and rebuild for other buyers.”

Several local builders say they were at or near production capacity before the Moore tornado, so they probably would not get too involved in the rebuilding effort. “It’s not their business model,” says Ken Ford, former manager of NAHB’s disaster assistance program. “You’re dealing with scattered lots, where the owners are trying to salvage the slab or pad.”

At least one production builder is trying to participate in the rebuilding effort. Home Creations has assembled special teams for the purpose of rebuilding and selling destroyed homes in Moore. Those teams are headed up by one of Home Creations’ sales managers, who lost her own home to the tornado.

The Moore tragedy also might be an opportunity for United-Bilt Homes, an on-your-lot builder that operates 22 offices in five southern states. The builder closed about 60 homes in Oklahoma last year, and its office is located on the outskirts of Moore. Mike Johnson, its general manager, says his company could triple its capacity in that market without making major changes to its business “because we wouldn’t have to travel that much.”

Terri Akers, executive director of the Central Oklahoma HBA, expects many of her group’s 300 builder-members to eventually “step up” and get involved in the rebuilding effort. But McCaleb and other builders say they are worried about not having access to enough construction labor once the rebuilding gets going in the next six to nine months.

Labor shortages would leave the door open for out-of-state contractors to fill the void. Oklahoma doesn’t require builders to be licensed, but to discourage fly-by-nighters and predators, cities issue permits to builders only if they can show they have worker’s compensation and general liability insurance coverage. And Oklahoma banks require all builders to carry risk insurance while a house is under construction.

Once Moore gets to the point where rebuilding is feasible again, builders are likely to interest its anxious residents with off-the-shelf, higher-performance options that are within buyers’ budgets and don’t rely on proprietary technologies, says Alex Lukachko, general manager for the engineering and architectural firm Building Science Corp. in Somerville, Mass.

Lukachko’s opinions are informed in part by the time he spent in Greensburg, Kan., a few months after the city was wiped out by an EF5 tornado in 2007. BSC was in the community of 1,400 people under the auspices of the DOE’s Building America program. Wind-resistant construction using ICFs or SIPs “didn’t play out financially” for Greensburg’s residents, recalls Lukachko, especially those who weren’t sure what insurance and government assistance would cover financially. So BSC leaned instead toward the simple and practical: roof tie-downs, hurricane clips, and threaded rods to hold houses onto their foundations. BSC also encouraged owners to include “hardened shelters” within the homes.

“In Greensburg, we were proposing energy-efficient new construction with a relatively low cost—between $90,000 and $120,000 per house,” he says. “But many of the houses in the area were only worth a fraction of that. The average sale price was something like $75,000. What this means is that the resources are just not there to pay for average-sized homes and at the same time protect them against flying trees, 2x4s, etc.”

Lukachko recalls that the BSC had similar problems rebuilding to higher standards after Hurricane Katrina. “This is a hard pill to swallow when your community has been destroyed and you are trying to rebuild your life. The most important thing is expedient construction with reasonable solutions to build homes inexpensively that people will want to live in.”