Behind the walls of Dan and Mary Flannigan's house in Holly Springs lies an almost unthinkable menace that has bedeviled the couple since they moved into their house five years ago this month.

Little did the Flannigans know then that the source of their troubles — a pungent sulfuric odor, corroding metals and numerous health issues — would appear to be their drywall. They contend it’s the same Chinese-manufactured drywall that has plagued homes across the nation but especially in the humid South.

The discovery has led the Flannigans to sue their builder, Stafford Custom Homes of Southern Pines. The couple had hoped to move out of their 1,900-square-foot, two-story home in the Valleyfield subdivision in mid-June. But years of pouring money into what they say were false fixes have taken their toll.

“We looked into it,” said Dan, who noted that he and his wife had considered moving into a nearby apartment complex. “But after reevaluating our financial situation, it looks like it might not be an option after all.”

The Flannigans’ lawsuit, filed April 6 in Wake County Superior Court, claims that Stafford Custom Homes should have foreseen that the drywall in the house could be harmful and damage mechanical systems. The lawsuit appears to be the first of its kind in North Carolina.

“They admitted to us that our house was in fact built using this Chinese drywall,” Dan said. “But still they’ve done nothing to fix it.

“We’re reasonable people,” he added, noting that he and his wife made numerous appeals to Stafford Homes to stand behind their work. “We just want what we paid for — a house without hazardous materials.”

An employee at Stafford Homes who answered the phone Friday declined to give her name but said that the company’s insurance provider was looking into the Flannigan’s case. She said the Flannigan’s house was the only one Stafford Homes was aware of that had problems with the drywall.

The company has declined to comment in previous stories for The News & Observer.

According to a recent article published in the Fort Worth Star-Telegram, the drywall problem appears to be concentrated in the Southeast, which blossomed with construction during the housing boom and where the damp climate appears to cause the gypsum in the building material to degrade faster. In Florida alone, the story says, experts estimate that more than 35,000 homes may contain the product.

The report also states that a Florida Department of Health analysis found that the Chinese drywall emits “volatile sulfur compounds” and contains traces of strontium sulfide, which reacts with air to corrode metals.

Numerous complaints have been filed in Florida and other states against manufacturers and installers of the defective drywall. It remains to be seen whether other lawsuits will be filed in North Carolina, although the Flannigans and their attorneys think it’s likely.

“We think it could be affecting numerous houses throughout the state,” said Raleigh lawyer Scott Harris of Lewis & Roberts, one of the attorneys handling the case.

Added Dan, “It’s impossible for us to be the only ones dealing with this.”

The lawsuit is just the latest in a series of steps the Flannigans have taken to rid their home of both the pungent “rotten eggs” smell that permeates the air and the corrosive black film coating everything from electrical wires to door knobs to picture frames.

Until about a month ago, the couple had no idea what was causing the problem.

Then one morning in late March or early April, Mary turned on the television news. She saw a segment detailing how Chinese drywall had affected homeowners in Florida.

She was stunned.

“When I saw it on the news, I knew exactly what the problem was in our house,” she said.

“The symptoms [homeowners] were having in Florida are exactly what we’re having here,” Dan added.

The Flannigans said they wish they had only known about the problem much sooner, before spending five years and perhaps tens of thousands of dollars repairing or replacing fixtures like their air conditioning unit, hot water heater and appliances. And that doesn’t even take into account what they’ve incurred in medical bills.

“We’re always tired and have sore throats constantly,” said Dan, who noted he and his wife both used to be more active. “We’re sure the house has something to do with it.”

Dan said his wife has battled severe cases of pneumonia several times and had to be hospitalized. And she has developed allergies for which she is now taking three separate medications, he said. But perhaps the scariest problem for Mary came when she had her tonsils removed in the spring of 2008.

“After she had her tonsils removed, the doctor was looking at them and said he had never seen anything like this before,” Dan said. “There were black holes in her tonsils.”

In addition, Dan noted he has developed trouble breathing that led a doctor at one point to question whether he smokes. “I’ve been going to the same doctor for probably eight or nine years, and he knows we don’t smoke,” he said. “But I’m always wheezing.”

“We can hardly sleep here anymore because of all the anxiety this has caused,” Mary said. “Something’s got to change.”

They said they hope their efforts will help prevent others from experiencing the same difficulties. “We’re trying to get the word out to as many people as possible so they’re not affected by the harmful fumes and don’t suffer through the health issues that my wife and I have gone through,” Dan said.

Wade Rawlins of the News & Observer contributed to this report.