March 28, 2016
Yet More On Chinese Drywall
By Michael D. Shaw
This column ran several stories on the matter of tainted and corrosive Chinese Drywall, including this one. Basically, thousands of people in several states were victimized by the effects of certain drywall products, which emitted a variety of sulfur compounds (mostly sulfides). Damage was sustained to copper wiring, coils in air conditioning systems, and a host of residential surfaces. Many affected homeowners also experienced an assortment of health effects, and complained of obnoxious odors.
The Consumer Product Safety Commission arranged for testing to be done, and published a series of reports. Among other things, emissions from numerous samples of drywall were measured—based on elegant work performed by Lawrence Berkeley National Laboratory. The cornerstone of the LBNL effort was its development of a test method, whereby samples of drywall were placed in a chamber, and its emissions, measured in micrograms per square meter per hour, were recorded.
I was a founding member of the ASTM committee charged with looking into test methods and standards for tainted drywall, and immediately endorsed the LBNL methodology. In fact, related chamber testing methods have been used for decades to evaluate formaldehyde emissions (originating from the laminating resins) for plywood and other manufactured wood products. Anyone familiar with analytical chemistry will recognize that this sort of direct measurement is as good as it gets, and should be embraced as the gold standard.
As it happens, though, only one other committee member—who is also one of the nation’s leading experts on evaluating structures for the presence of tainted drywall—agreed with me. I refer to Michael Foreman of Sarasota, FL. Ironically, everyone on the committee acknowledged that the LBNL chamber testing method was the best, but politics got in the way.
Early in the process, CPSC was quite desperate to facilitate on-site testing by home inspectors, and discouraged lab methods, although they had paid LBNL millions to do first-rate laboratory analysis. Instead, CPSC recommended “markers.”
These markers should be semi-quantitative, but reliable indicators of emitting drywall that could be performed on the fly. However, as we discussed, the original marker—strontium—proved to be wildly inconsistent, and thus no marker at all. It was quietly disavowed by CPSC. Unfortunately, many home inspectors had already purchased expensive x-ray fluorescence (XRF) spectroscopy units to perform the strontium testing.
Not learning its lesson, CPSC and its co-conspirators then recommended orthorhombic sulfur (S8) content as their new marker. This was a curious choice for two reasons:
1. Unlike strontium testing, S8 assays must be done in the laboratory.
2. S8 does not correlate with sulfide emissions.
Notably, the latter point was argued—unsuccessfully—with CPSC and ASTM, even though their own data showed that S8 did not correlate with emissions. Incredibly, S8 became the de facto standard, and demonstrates how bad politics can destroy good science.
Which brings us to a recent development. Earlier this month, a single family residence in Land O’ Lakes, FL was assessed for the presence of tainted and corrosive Chinese drywall (TCDW). Although no visual evidence of the material was found inside the house, a disturbing finding did emerge from the garage: Every wire connected to the main electrical panel (located in the garage) showed telltale corrosion, usually identified with TCDW.
Such corrosion, when observed—as this was—on an outside wall can also be explained by sewer gas or sulfur-containing irrigation water. But in this case, no other corrosion was observed anywhere on devices attached to exterior walls. Moreover, when the drywall attached to the electrical box was tested for S8, it fell well below the Florida TCDW standard of 10 milligrams per kilogram. Therefore, the residence did not qualify as a possible, probable, or confirmed case of corrosive drywall, under Florida law.
Oddly, the home testing company did not provide an explanation for the observed and very obvious wire corrosion.
Michael Foreman, who has tested hundreds of homes, and wrote the original ASTM visual inspection protocol, is nearly certain that the drywall adjacent to the electrical panel is corrosive. Indeed, what other explanation could be proffered? He is currently running a jar test—essentially a poor man’s version of the LBNL testing—in which a piece of new copper tubing is placed in a sealed jar along with a measured piece of the suspect drywall.
Any corrosion on the tubing, evaluated after 90 days, but usually observable well before that time, is definitive for TCDW. Foreman, the homeowner, and I look forward to presenting the jar findings.
Whom are you going to believe? S8 or your lying eyes?