Builders, homeowners, and others should soon have some answers why some drywall imported from China during the height of the building boom has been corroding metal in houses and making some people sick.

Government investigators have spent the summer conducting experiments, researching imports, and even visiting China in an effort to determine the problems with the suspect drywall, how widespread the issue is, how dangerous the issues are, and how to address the issue. The reports are expected to be released starting in late August and continuing through September.

Examining Chinese drywall

The research has been wide-ranging.

To determine health hazards, Chinese- and American-made drywall samples have been sealed in isolation chambers so any gases they emitted could measured and identified. Other drywall samples were crumbled and analyzed to determine what, besides gypsum, materials are in the building product.

Special monitors were installed in 50 homes--15 of which were "control homes" with no problems and 35 of which had generated owner complaints of odors and corrosion--where they have been sampling the air for various chemicals.

Engineers are studying corroded switches and electrical outlets, air conditioning coils and gas lines, smoke alarms and appliances, calculating how much exposure to the drywall would cause them to fail. There have been two fires attributed to the effects of Chinese drywall.

Investigators from China visited houses with smelly drywall and corroded copper in Florida and Louisiana. Now American investigators are visiting gypsum mines and wallboard plants in China where the suspected defective product was born.

Researchers also have been meticulously examining import records to determine just how many sheets of drywall from China arrived on U.S. shores in 2006. That year, the twin forces of hurricanes (and the subsequent necessary repair and rebuilding) and a feverish home building climate resulted in drywall demand that was high enough to make it cost-effective to import the heavy gypsum board from halfway across the world.

The U.S. government’s investigation began five months ago when a team from the U.S. Consumer Products Safety Commission visited four Florida houses with Chinese drywall to examine the notorious homes and drywall problems themselves. They spent three days inhaling the noxious odors, noting the corroded metal in air-conditioning coils, circuit breakers, plumbing fixtures, mirrors and picture frames, and experiencing irritated throats, scratchy eyes and headaches, according to a report filed by the CPSC.

The experience was convincing enough that they convened a meeting of senior staff from CPSC, the Environmental Protection Agency and Centers for Disease Control to launch a joint investigation into the potential health hazards of the drywall within three weeks.

Facts about Chinese vs. American drywall

Here are some things researchers know so far about the drywall issue.

  • The Chinese-made drywall from a small sampling of affected homes is different from U.S.-made drywall, a chemical analysis by the EPA determined.

  • In what might be no surprise to anyone who has been in one of these homes, the Chinese-made drywall had dramatically higher levels of sulfur. Researchers found that the Chinese-made drywall had between 83 and 119 parts per million of sulfur, while the four samples of U.S.-made drywall had none.

  • Organic compounds found in acrylic paints were also found in some of the Chinese samples.

  • The metallic element strontium was found at between 2,570 and 2,670 parts per million in the Chinese drywall compared to 244 to 1,130 parts per million in the U.S. samples.

  • Worries that the drywall might present a radiation hazard were put to rest when 21 samples, including four from affected homes, and 17 from U.S. manufacturers were found to have about the same amount of radiation as each other and no more than is typical “background” radiation in the environment.

  • The point of origin of at least some of the troublesome drywall was the Shan Dong province in China, specifically the LuNeng mine, which in 2006 was the sole source of gypsum for one large manufacturer of drywall that imported more of the drywall exported to the U.S. in 2006 than any other.

  • At least 6.2 million sheets of drywall were imported from China in 2006 and the number has been climbing. Figuring out the exact total is challenging because drywall shares an import code with ceiling and acoustic tiles.

Builders and Buyers: Who's been affected by Chinese drywall?

Since December 2008, the CPSC has had 1,046 reports from residents in 24 States and the District of Columbia who believe their health symptoms or the corrosion of certain metal components in their homes are related to the presence of drywall produced in China. Florida residents, by far, lodged the most complaints, 77%, with Louisiana a distant second at 13%.

The number of lawsuits related to the drywall hasn’t been tallied up yet, but they appear to be growing too. In the meantime, a number of builders have acknowledged and set aside funds to pay to fix the houses they built with the faulty drywall. Lennar, for example,  was an early discoverer of the problem and probably the first to start studying and attempting to remediate the issue. The company has also sued the drywall suppliers suspected of installing the defective board.

WCI Communities, Beazer Homes USA, Meritage, Ryland Homes, Taylor Morrison Homes, and Standard Pacific Homes have all said they built homes that include the drywall. Some have set aside funds to repair the homes, which could be costly if the solution is to rip out and replace all the tainted boards. Avatar Holdings recently said in a Securities and Exchange filing that it had built one home with Chinese drywall that it knows of and estimated the cost of repairs to be $70,000.

For more information on the investigation:

Teresa Burney is a senior editor at BUILDER and BIG BUILDER magazines.