MOORE, Okla. — After living nearly 20 years in their one-story brick home, Sherry and Larry Wells finally won the lottery — for a state rebate on a home storm shelter. A contractor finished installing the concrete bunker beneath the slab of their garage in early May. About three weeks later, the shelter saved their lives when a tornado that killed 24 people tore through their neighborhood.

Oklahoma’s SoonerSafe incentive program offers federally financed rebates of up to $2,000 to residents who install storm shelters. The state uses a lottery-style drawing to select rebate winners from among the thousands of online applications. Sherry Wells and her husband decided to get the biggest shelter available— a vault-like box with wooden benches — at a cost of $4,800.

Should residential storm shelters be mandatory in the midst of Tornado Alley? Absolutely, says Sherry Wells, “it’s the best thing ever.”

But not a single state currently requires them in homes. And not many communities do so either, though officials in the Oklahoma City suburb of Moore are now considering it.

Despite the life-saving potential of personal storm shelters, the cost remains a deterrent. So, too, does a general resistance to government mandates in politically conservative states such as Oklahoma.

Some shelters still are dug underground in the backyard. But they are increasingly made with specially fabricated concrete and steel doors to meet Federal Emergency Management Agency specifications. And they aren’t necessarily underground. In some cases, closets or bathrooms are being fortified to double as “safe rooms” that can withstand furious winds even if the rest of the house is blown away.

Moore Mayor Glenn Lewis wants to propose a city ordinance requiring all new homes to have storm shelters. But realistically, he said, city officials may be able to require them only in new assisted living facilities and apartment complexes because of cost concerns. Contractors will be part of the conversation with the City Council.