To the consternation of builders and the delight of firefighters and municipal officials, every one- and two-family house built in Pennsylvania after Jan. 1 will be required to have fire-sprinkler systems.

The mandate - part of the 2009 International Residential Code and applicable to new construction, not remodeling - was challenged in Commonwealth Court by the Pennsylvania Builders Association and others after it took effect for townhouses this year.

The builders argued that changes to the residential code, especially the sprinkler rule, would effectively increase the cost of a typical new house $15,000, would have an effect "on the demand for their home-building and remodeling services, and will adversely affect the availability of financing of homes."

The court dismissed the association's petition earlier this year, describing the argument as "disingenuous."

"It is the same argument they have been making since 1989," said John Waters, chief fire marshal and director of safety and code enforcement for Upper Merion Township, which has had its own sprinkler regulations since 1988.

"The builders have been less than forthright in their position," added Waters, who is cochairman of the Pennsylvania Residential Fire Sprinkler Coalition.

Undeterred by its setback in court, the builders association, in a "consumer alert" on its website, urges anyone interested in having a house built to sign a contract before Dec. 31.

Building permits for one- and two-family houses approved by that date will not be covered by the new rules, and, because of action taken earlier this year by Gov. Rendell to help the construction industry, those permits will be valid until 2013.

There is some anecdotal evidence that builders have been racing to municipal offices throughout Pennsylvania to obtain permits, though the most recent data from the U.S. Commerce Department show residential permits at the lowest level in 40 years.

While arguing that they do not oppose residential-sprinkler systems but think the choice should be left to consumers, the builders have vowed to try again to have the code rolled back to 2006.

"Unfortunately, the added cost of this mandated safety feature just moves the dream of homeownership further out of reach for some Pennsylvania families," association president Joseph Mackey said. "We will be back [in Harrisburg] for the new session in January with permanent residential-sprinkler-relief legislation."

New Jersey has not adopted the residential-sprinkler code, although some municipalities have their own requirements.

Pennsylvania builders contend that state code has required hard-wired smoke detectors in new houses for years, "which provide a better-than-99-percent chance of surviving a home fire."

The builders association also maintains that consumers should decide whether they want the additional protection, saying that few have chosen the sprinkler option. The group cites a 2006 study by the National Association of Home Builders that said just 15 percent of all new-home buyers wanted sprinkler systems.

The Burn Foundation counters with a 2005 Harris Interactive poll of U.S. homeowners in which 69 percent of respondents believed having a fire-sprinkler system increased the value of a home.

The builders have received support from House Republican policy committee chairman Stanley Saylor of York County.

With the state housing market "beginning to recover from the worst recession in generations, imposing a mandate of this size could set that recovery back months or even years," Saylor said.

Waters said the benefits of sprinklers far outweighed their cost. According to the Fire Protection Research Foundation, the national average cost to install a sprinkler system in a new house is $1.61 per square foot, or $3,656 for a house of 2,271 square feet.

"We ask [the builders] where they get their figures, but we can never get an answer," Waters said.

The builders say their numbers are based on data collected "from at least 25 Pennsylvania home builders with experience putting sprinklers in homes in our state."

The average cost of fire damage in a house without sprinklers is $45,000, compared with $2,100 in the same house with sprinklers, according to the Burn Foundation.

"Those who are pushing to have residential sprinklers deleted from the code are not responsible for fire protection in their communities, yet they are claiming themselves to be experts in fire safety," Waters said.

"They are advising elected officials, who are now responsible, to ignore the long-term impact that the installation of sprinklers can have."

Contact real estate writer Alan J. Heavens at 215-854-2472, aheavens@phillynews.com, or Twitter: @alheavens.