Chinese Drywall Inspections

Jan 18, 2022

During the Visual Inspection the inspector checks for common signs of Chinese Drywall in the home, such as an odor of sulfur, corrosion / blackening of copper wires and pipes, and markings on unpainted drywall indicating that it was made in China. If this inspection reveals indicators of Chinese Drywall an Intrusive Inspection may be performed. At that point small samples of drywall will be taken from various areas in the home and sent to a laboratory for testing. Results of the lab testing can take up to two weeks. Additional Fee.

Pure Sulfur May Be Culprit in Chinese Drywall

Scientists addressing a conference in Tampa, Florida, on defective Chinese drywall have offered a more detailed explanation of why the material produces gases that corrode copper elements in buildings, such as wiring and air conditioner coils. According to reporters who attended the "Symposium on Corrosive Imported Drywall," a $300-a-head event sponsored by the University of Florida, a leading investigator into the problem says the gas releases can be traced directly to the presence of pure sulfur in the panels. Bacteria, chemical reaction debated as roots of drywall problem," by Allison Ross. But "the bacteria theory needs a lot of work," said Florida Department of Health toxicologist David Krause, pointing out that while the drywall may contain bacteria, no connection has yet been established between the bacteria and the sulfuric emissions . On the other hand, if carbon monoxide is the limiting element in the formation of carbonyl sulfide, then according to basic chemistry it would make sense that gases are emitted at a steady rate until most of the sulfur in the material is consumed — subject only to the continued availability of carbon monoxide in the ambient air. The firm, said, "If you remove it, clean up the debris, ventilate the home and rebuild, there's no reason you can't expect success.

The Sarasota Herald Tribune says that toxicologist Tom Gauthier of the firm Environ International, hired to study the problem by builder Lennar Homes, has found that the elemental sulfur in the panels reacts with naturally-occurring carbon monoxide in the ambient air to form carbonyl sulfide. The carbonyl sulfide then reacts with moisture and air to produce hydrogen sulfide and carbon disulfide. All three gases have been detected in test chambers and in homes containing the Chinese drywall. And according to Gauthier, Environ was able to stimulate a much faster release of the offending gases by placing the drywall in a chamber rich in carbon monoxide.

Government scientists lag behind Environ's investigators and other outside researchers, notes the Herald Tribune (Commission (CPSC) scientists in a report last month, the paper notes, "were not yet even able to state there was an association between the tainted drywall and the corrosion of copper wires, pipes, air conditioning coils, and other metal components" — even though "Florida, along with a host of private consultants, has long since determined that there is a strong association between the drywall and corrosion." Tom Gauthier's results were corroborated by Michael Tuday, research and development director of California-based Columbia Analytical Services, Inc., and Zdenek Hejzlar, an expert in the environmental and toxic health fields with the Fort Myers office of Engineering Systems Inc., reports the Fort Myers News -Press. Blame sulfur for drywall woes, experts say," by Mary Wozniak). "The three scientists, in separate presentations, confirmed that the sulfur interacts with indoor air and other agents, like carbon monoxide, to cause different sulfur compounds to be emitted from the drywall in low amounts. It is enough to cause the drywall’s corrosive effect on air conditioning coils and other metal items in the home, they said.

Environ scientists also told the conference that in their view, removing the bad drywall and replacing it with fresh, sulfur-free drywall should eliminate the problem, according to the Sun Sentinel paper ("Chinese drywall and start over, scientist advises" by Paul Owens). James Poole, an industrial hygienist with Lennar Homes, which has torn out and replaced the defective drywall in dozens of homes already, refused to comment, the Sun Sentinel reports. But Heather Keith, a lawyer for GL homes, which has replaced drywall in at least 20 units, told the paper that customers were "happy" with the fix, saying, "There are no reported or ongoing health or odor issues. I'd be surprised if the scientific community would say that the extensive repair that involves the complete removal of the interiors of a house is premature or insufficient.”

Call Our Office to Schedule a Chinese Drywall Inspection: 713-723-3330

Current Pricing:

  Chinese Drywall Visual Only:   $355

  Chinese Drywall Visual plus Samples Taken:   $540 + Lab Fee

  Lab Fee:   $125 per Sample / Minimum of 3 Samples

Case Definition (12-18-09) for Drywall Associated Corrosion in Residences.

This revision of the 03-31-09 Case Definition reflects our current understanding of this emerging problem and the results of recently released information regarding corrosive drywall testing. The sole purpose of this case definition is to help identify homes that are affected by corrosion associated with drywall emissions. The case definition is NOT intended to evaluate the health risks for occupants or to evaluate occupant exposures to corrosive emissions.

This case definition is NOT regulatory in nature or required to be used by those inspecting homes. This case definition is provided to the public for informational purposes only and its use is strictly voluntary. Adoption of this case definition for purposes beyond its intended use is at the risk of the user. Criteria to demonstrate that a home is not affected by corrosive drywall emissions may require a different approach and inspection criteria that are not described in this document.

This version of the case definition enables the user to rank homes as a possible, probable, or confirmed case. Homes that exhibit the sentinel indicators of drywall associated corrosion are defined as possible cases. All three sentinel indicators of Criteria 1 must be met for the home to be considered as a possible case. Criteria that define a probable or confirmed case are described in later sections.

For Homeowners

Criteria 1:

Sentinel Indicators of Drywall Associated Corrosion (Possible Case = all 3)

1. The home was constructed or renovated with new drywall since 2001.

2. Observed corrosion of air conditioner evaporator coil exemplified by black corrosion on copper tubing components. The corrosion can result in refrigerant leakage making it impossible to cool the home requiring coil replacement. Coil failures indicative of this problem typically occur every 6-14 months

3. Observed metal corrosion, indicated by blackening of one or more of the following:

copper wires, ground wires, and electrical connectors

un-insulated and un-coated copper pipes and fittings

chrome-plated bathroom fixtures

silver and copper jewelry

mirror backing in bathrooms

If you have answered yes to all three of the above indicators, the home meets the criteria for “possible case”. Continue to Criteria 2 or 3 only if home meets the criteria for “possible case”. Trained professionals performing home assessments based upon this case definition should use their experience, training, and professional judgment to establish their inspection procedures and sampling strategies.

Professional judgment is necessary to determine the number of samples and weight of evidence needed to meet each set of criteria. A trained professional, not the homeowner, should conduct inspections and testing described in Criteria 2 and 3.

For Trained Professionals

Criteria 2:

Supporting Indicators of Drywall Associated Corrosion (Probable Case = 1 or more)

1. Observed markings on the back of drywall indicating the country of origin is China.

2. Objective analysis of drywall in home finds Strontium levels exceed 2,000 mg/kg (ppm), indicating the gypsum used in the drywall was probably mined in China. Analytical methods commonly used for this include XRF and ICP. 2, 3, 5, 7, 8, 9, 10, 11, 12

If you have met the criteria for “possible case” and answered yes to at least one of the above indicators in Criteria 2, the home meets the criteria for “probable case”. These criteria do not confirm that the drywall causes corrosion. Identifying the origin of the drywall is considered a screening tool for suspect drywall, but confirmation requires analysis described in Criteria 3.

Criteria 3:

Confirmatory Evidence of Drywall Associated Corrosion (Confirmed Case = 1 or more)

1. Elemental sulfur (Orthorhombic sulfur, cyclooctasulfur, S8) content of gypsum core exceeding 10 mg/kg (ppm), indicating the gypsum in drywall samples from the home contains the source material that is believed to contribute to the reduced sulfur gasses emitted from corrosive drywall. Analytical methods commonly used for this include GC/ECD, GC/MS, or HPLC. 1, 2, 3, 4, 6, 8, 9, 10, 11

2. Laboratory analysis of suspect drywall headspace for reduced sulfur gas emissions (H2S, COS, CS2) indicating drywall samples from the home emit reduced sulfur gasses capable of causing copper corrosion. Analytical methods commonly used for this include GC/SCD.6 Results that are indicative of corrosive drywall must be established by each laboratory based upon internal procedures, comparison to control samples, and validated methods.

3. Qualitative analysis of suspect drywall for its ability to cause corrosion/blackening of copper under controlled conditions, indicating drywall samples from the home emit gasses capable of corroding copper. Results that are indicative of corrosive drywall must be established by each laboratory based upon internal procedures, comparison to control samples, and validated methods.

If you have met the criteria for “possible case”, ruled out other sources of hydrogen sulfide as significant contributors to copper corrosion in the home, and receive positive results on a sufficient number of samples from one or more of the above evaluations in Criteria 3, the home meets the criteria for a “confirmed case”. Some confounding factors that should be excluded as causes of observed corrosion are hydrogen sulfide from well water, sewer gas, or soil gas.

Odors and Symptoms

* Use of odors as an indicator of drywall associated corrosion is limited. Odors have not been reported in all homes exhibiting drywall associated corrosion.

* Occupant reported health symptoms have limited use in identifying homes with drywall associated corrosion. The symptoms reported by occupants are not unique or consistent across affected homes.

* Documenting the presence of odors and/or occupant symptoms may be important to public health agencies, but their relationship to the presence or absence of drywall associated corrosion in homes remains unclear.


Prior to embarking on efforts to remediate the home, one should perform sufficient evaluation to ensure the criteria for “confirmed case” are met and rule out confounding factors.

Please note: The Florida Department of Health has not examined remediation methods and does not endorse any specific methods or techniques to conduct an effective remediation of affected homes.