The same is true in Texas, Alabama, Kansas and Hawaii, where in the past four years state governments have enacted bills forbidding cities and towns from requiring sprinklers in new homes. A dozen have forbidden statewide building code councils from including the requirement in their guidelines.

Advocates — including firefighters, fire safety groups and the sprinkler industry — say sprinklers are needed more than ever in new homes because of builders' heavy use of prefabricated construction materials. The materials burn faster, firefighters say, causing more destruction and making rescue attempts more difficult.

The state laws forbidding sprinkler requirements are unprecedented, public-safety advocates say, and underscore the political clout of the home-building and real estate industries. A Reuters review of lobbying records from five states that considered sprinkler legislation since 2009 shows the groups grossly outspent fire sprinkler advocates.

"This is the only code provision that I'm aware of in 30 years of being in this business, where we've seen a preemptive strike that says, ‘You can't even consider it. It's not allowed,'" said Gary Keith, vice president of field operations for the National Fire Protection Association, a nonprofit advocacy organization. "That's unheard of with any other kind of provision."

LIGHTWEIGHT RISKS

Four years ago the landscape looked strikingly different. Coming off the housing market's peak years, scores of cities adopted fire sprinkler rules despite opposition from builders. And in 2009 sprinkler advocates cheered when the International Code Council, a nonprofit organization that develops national model building codes, voted that fire sprinklers should be required in all new one- and two-family homes.

Then came the worst housing market in U.S. history and a fragile economic recovery. Against that backdrop, lobbyists for the home-building industry, which opposes mandatory sprinklers, gained traction with lawmakers. Even as home building picks up after years of stagnation -- the U.S. Census Bureau projects more than 500,000 single-family housing starts this year -- many lawmakers remain wary of sprinkler regulations.

"When you start mandating a fire sprinkler system, you are going to price a lot of people out of these new homes," said Ned Munoz, vice president of regulatory affairs for the Texas Association of Home Builders, which lobbied heavily for anti-sprinkler legislation.

Although preemptive state laws have been imposed in other public-health policy areas, laws preempting building or fire safety regulations are unheard of, said Mark Pertschuk, an expert on preemptive laws with the Prevention Institute, a California nonprofit organization funded by private health foundations, government agencies and public health groups.

"They haven't just taken away local control," Pertschuk said. "They've stopped the community debate about public safety and health."

Most cities have required sprinklers in larger multifamily residences for decades. Fire safety advocates want to extend the requirement to all single-family homes, often citing the widespread use of lightweight construction, a building technique that relies on prefabricated and engineered wood products.

Designed to carry a greater load with less material, the prefabricated components are made from real or man-made wood fragments held together by glue or metal fasteners. The materials are commonly used to frame roofs and flooring. Assembled in factories and shipped to construction sites, these building components significantly cut down on construction time and cost. Builders also say the materials are better for the environment, because they use less wood, reducing deforestation.

But both real-life and test fires have shown that structures with lightweight construction burn much faster and collapse sooner than traditional solid-wood frame construction. That, firefighters say, makes fires harder to fight and shortens the time occupants have to escape a blaze.

"Not only is that second floor going to come down on your head in a very short period of time, the roof is going to collapse," said Danny Hunt, fire marshal in Nashville, Tennessee, where he said roughly 90 percent of new homes use lightweight construction.

Lightweight construction was introduced in the 1960s, and became popular in ensuing decades. Today, by their own accounts, the nation's largest builders use the materials extensively in new homes, as do many custom home builders. Firefighters say most homes built in at least the last 20 years contain the materials.

The numbers of fires, deaths and injuries related to lightweight construction are unknown, experts say, because most fire reports don't record the construction method.

Firefighters reported more than 1,300 incidents from 2006 to 2010 in which lightweight construction hurt their ability to suppress fires in single-family or multifamily homes, according to a Reuters analysis of the Federal Emergency Management Agency's National Fire Incident Reporting System, the nation's largest fire database. At least 90 percent of those homes did not have sprinklers installed. Twenty civilians were killed and at least 260 firefighters and civilians were injured in those fires.

An additional Reuters review of federal and local firefighter fatality investigations found at least nine firefighters killed since 2000 while battling residential lightweight construction fires.

In May a police captain, his wife and two teenage daughters were killed in a Carmel, New York, house fire started by his son's cigarette butt, tossed in mulch. The fire spread so quickly that the house collapsed within 10 minutes, which fire officials attributed to the home's lightweight construction.

"I was there the morning of the fire," said Eric Gross, a Carmel resident who serves as public information officer for the Putnam County Bureau of Emergency Services. "It was horrible. The firemen got there within a matter of minutes, but seconds later the whole roof collapsed. Once the thing came down, that was the end of it. There was nothing they could do."

HOMEOWNER'S CHOICE?

Sprinkler systems would offset the danger created by lightweight construction, firefighters say. A 2008 survey by the Fire Protection Research Foundation found the systems add an average $1.61 per square foot, or $3,864, to the cost of a new 2,400-square-foot home. Some insurance companies offer policy discounts as high as 10 percent for homes with fire sprinklers.

California and Maryland are the only states that require sprinklers in all new homes.

In many states, builders have successfully argued that sprinklers are not only expensive but also unnecessary, thanks to a drop in fire fatalities related to the widespread installation of fire alarms in the past 30 years. Installing sprinklers, they say, should be a homeowner's choice.

"I'm for fire safety," said Texas State Representative John Otto, a Republican. "But you're taking the decision out of the hands of the homeowner, and you're mandating something that ought to be left to the homeowners."

Otto sponsored the Texas legislation, passed in 2009, forbidding local jurisdictions from requiring sprinklers in new one- and two-family homes. The law's greatest proponents, builder and Realtor trade groups, spent between $1.7 million and $3 million lobbying that year -- at least four times what sprinkler advocates spent.

In Florida, home builders enlisted the political muscle of a former political director for ex-Governor Jeb Bush to lobby state legislators against sprinkler requirements. In 2010 lawmakers voted to block the state code-making body from adopting any sprinkler mandates.

"There's nothing to stop somebody from having a fire sprinkler system installed in their house," said Jack Glenn, technical director for the Florida Home Builders Association. "But to mandate it for the entire population is a very expensive proposition."

(Editing by Lee Aitken, Janet Roberts and Douglas Royalty)