Reinforced with Kevlar, Stormroom is available with fully customizable walls measuring up to 12 feet long. The room can be finished to match any wall and allows for electricity, plumbing, and HVAC integration. The durable yet lighter-than-steel Kevlar also allows for wireless use and radio reception. The panels use structural steel connectors and attach to a concrete slab foundation with an epoxy anchoring system.

This simplistic panel design bolts together using Grade 8 steel hardware and anchors to the slab floor. The single-motion posi-lock door latch also provides a fail-safe exit for occupants. During debris-impact testing at Texas Tech University, the structure withstood the highest number of impacts of shelters tested, according to the manufacturer. Sizes range from three- to 40-adult capacity.

Offering a range of safe rooms, panic rooms, and security vaults, these drop-in and modular rooms can be outfitted with wood overlays or sheet rock as well as electrical outlets, lighting, secure venting, and communication line conduits. High-strength, wedge-type anchors over concrete slabs provide FEMA rated high-wind protection. Also available are security pocket doors, high-caliber ballistic protection, and two-hour fire protection.

The NASCAR-type safety cage inside this all-welded steel storm shelter can hold about 25 midsize cars, according to the manufacturer, and is bullet-resistant. Three commercial-grade locks allow the room to double as a gun safe or vault, while a patent-pending door system ensures users won’t become trapped inside. Finished units require the loss of only 2.5 inches per wall and install with a Hilti anchorage system.

There’s a lingering perception that underground storm shelters are the only protection people have against powerful tornadoes, but research conducted by Texas Tech University and manufacturers shows aboveground safe rooms provide adequate safety. “Technology has caught up to the point where you can be safe aboveground,” says Marty Strough, CEO of Berryville, Ark.–based Storm Rooms of America.

EF5 tornadoes are the most destructive, according to the Enhanced Fujita (EF) scale, which replaced the Fujita scale in 2007 and rates the strength of tornadoes in the U.S. and Canada based on the damage they cause. The Texas Tech Debris Impact Testing Lab certifies aboveground shelters. As of April, 92 shelter manufacturers completed debris-impact testing to EF5 standards.

“If the shelter has been tested as an EF5, it’s good for a 250 mph tornado,” says Larry Tanner, a lab research associate. In addition to high-wind resistance, the EPA requires that an in-residence shelter be easy to access, so many are installed in closets and utility rooms.

The Texas Tech lab recommends indoor shelters over in-ground ones because residents are less likely to use outdoor shelters and often encounter flying debris when they do.

Strough, who was a home builder for 36 years before entering the shelter business, advises builders who are debating whether to purchase a prefabricated shelter or to build one on site to check first with their insurance provider. “General liability policies look at that as a specialty, and building a shelter is something they’re going to charge a lot more money for. I don’t know of any general liability policy that will pick that up.” As a result, he recommends using factory-made units and having expert installers take on the “huge amount of [installation] liability.”

Tornado Alley encompasses much of the Great Plains and portions of the Midwest, but few homes there have safe rooms. Moore, Okla., certainly is no stranger to tornado sirens, but you wouldn’t guess that by the number of shelters the city boasts. Emergency shelters and safe rooms aren’t required by code in Moore, and when a milewide tornado tore through town in May, only about 1 in 10 new homes had one, according to a report in The New York Times.

Moore city officials are resisting mandating shelters—which typically cost thousands of dollars per residential unit—arguing that it would make housing too expensive in a market where the median home sales price was $123,800 in 2012, according to Metrostudy, a sister company of BUILDER.

“To say that every new home must have a tornado shelter … that would be really difficult for people to be able to have a house at all,” said Robert Crout, president of the Central Oklahoma Home Builders Association.

Read more about how to build safer homes in disaster-prone areas.