Inspecting for Chinese Drywall

Different ways to inspect for the presence of  contaminated drywall.

Like anything else in the inspection business there’s always several ways to inspect something. One way or the other doesn’t necessarily make one right or one wrong however with anything due diligence is always a good course to take. Keeping yourself educated, doing research and keeping abreast of all the issues regarding todays housing market makes us better inspectors. Today I’m going to talk about the many ways to inspect for contaminated drywall.


Black A/C Coil

Black copper pipe

First there is the Florida Department of Health self-assessment guide that can be found on their web site. This self-assessment guide is the “threshold inspection guidelines”  that are used by many home inspectors. In this guideline we determine what year the home was built and do a visual examination. In this visual inspection items such as air conditioning evaporator coils, plumbing fixtures, electrical wiring, mirrors and many other metallic

Black Electrical wires

materials in the home are inspected for tarnishing. Tarnishing is caused by the out gassing of the contaminated drywall. Then there is the inspection of small sample pieces of drywall in regards to color. It is found that American-made drywall is very white  in color than Chinese drywall which has dark particles embedded in the drywall composition or gypsum core from contaminates. We also enter the attic space and wall cavities using equipment such as a Borescopes  we try and look for identifying markings on the back side of the drywall in the home that may give us an indication where the drywall was manufactured.  

Be Aware that all drywall made in China is not contaminated and that there are some American-made drywall that is contaminated.

Lastly but not least in the threshold inspection a smell or odor test is done. Yes, I said a smell test. Believe it or not the unusual odor characteristic of contaminated drywall, if prevalent is an

Made in China

excellent indicator of problematic Chinese drywall. The smell tests are better done with the home having the HVAC system or air-conditioning system turned off for a day or two. These are basically the six items that I consider a threshold inspection. The state of  Florida and United States Consumer Product Safety Commission threshold inspection is the same except they do not include color comparison of  the gypsum core samples.

Of course with these methods there are false negatives. Owners and sellers can cover up these problems with the equipment replacement, spraying cover up type fragrances, lowering the humidity in the home and a plethora of other cover up type methods. There are also other reasons why tarnishing can happen to metal objects such as well water and Gyp-Crete another building material used in multi story type dwellings and buildings.

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Edge Tape Identification

 There is one other visual inspection it can be done and it’s called an, “ edge tape identification inspection”. This step can corroborate the findings in the threshold inspection. In this inspection there’s very little damage done to the structure. Simply remove the baseboard from any given area locate where the drywall butt joints are in locate the edge tape. Edge tape is normally applied to sheet rock for shipping purposes because it shipped two sheets together and the edge tape keeps the two sheets connected. Some Chinese drywall is been known to be manufactured with no edge tape, plain white paper edge tape, or clear plastic edge tape. Other Chinese drywall has specific color patterns that are known to be indicators of contaminated drywall.

LABORATORY TESTING- there are of course several testing methods used in laboratory testing. Here are some of the samples: 

Air-Sampling: air quality tests are very unreliable and they are only about 50% accurate. The most common gas they look for sulfur dioxide. They also checked for carbon disulifide, carbonyl sulfide and dimethyl sulfide. In may vary from one lab do another.

 Measuring sulfur Strontium carbonate:  by Field testing or by using hand-held x-ray devices or in a lab environment. Strontium can have false positives and false negatives and is not a reliable indicator. X-ray devices are available on the market, PX-Ray fluoroscopy devices ( XRF). This equipment is typically used in metallurgy and manufacturing of machined tools and parts. Within the last year it has been ruled by a federal judge that this type of testing has become unreliable in the detection of contaminated drywall. This is not to say that this cannot be used as just another tool to be used in the investigation of contaminated drywall but without proper surface preparation can give false negatives and false positives.

 Measuring sulfur off-gassing: elemental sulfur and sulfur is prevalent and non-problematic as well as problematic Chinese drywall and is often a false positive which must be supplemented by the visual inspections noted above and fails to distinguish good Chinese drywall from bad. The jury is out on this one some feel that this is useful some feel that it is not. 

Carbonate: in the form of calcite and all my can be found in both good and bad drywall American and Chinese.

 Organics: problematic Chinese drywall is often gray in color due to larger amounts of organic contaminants. Levels of organic matter cannot be the only factor to distinguish contaminated drywall. If there is corrosion and darker color content in the drywall the conclusion would lean more toward contaminated drywall.

 So where does all this leave us. It appears that if we combine field observations and laboratory observations we can come up with a definitive answer to whether or not the structure has contaminated drywall. Studies and procedures developed by Certified Mold & Allergen Free Corporation in conjunction with Biostratigraphy Laborotory and Dr. Gary Rosen Ph.D. have come up with a 12 point assessment procedure leaving the structure with very little damaging impact.

 The first five points of the 12 point assessment is laborotory related.

  1. Observations & testing of the reinforcement fibers within the drywall gypsum core
  2. Observation & testing of the fiber type within the gypsum core.
  3. Testing the particulate reaction to acid, the reaction of carbonate in the drywall to strong acid.
  4. Observation of dark particles present in the gypsum core, dark particles are organic contaminants.
  5. Observation of air voids size distribution within the gypsum core. Chinese drywall is denser than American drywall.

 Points six through 12 are field related assessments as noted above. 

  1. Edge tape identification
  2. observations of tarnished metals such as copper
  3. check the drywall thickness
  4. that the drywall have an odor
  5. examination of the drywall core for color
  6. check for brand or labeling on backside
  7. observation of HVAC coils 

In conclusion:  You would take your lab data and your field observations and come to a conclusion using the  12 point assessment. This would come at a much lower cost per sample that “headspace analysis”. Using this 12 point assessment  you would now determine if it’s Chinese drywall are not—-you determine if it’s problematic Chinese drywall are not- and the system is completely nondestructive and easy to interpret.

The downsides are minimal: Biostratigraphy the only laboratory that does it this way however the report is published and open for anyone to use.  The turnaround time is 5 to 6 days and not immediate. 

I find it many times I’m losing a home inspection because a competitor will include a Chinese drywall inspection for free along with his normal home inspection. If I were a customer I would be very wary of this service for free. To properly perform the six field related assessments noted above will take approximately one to two hours and report writing, photo editing at least one to one and one half hours. Something’s going to give and its more than likely going to be the quality of both inspections.

Fred Sylvester, of Accredited Building Consultants, is a State of Florida Certified Home Inspector and Commercial Building Inspector with over 35 years of construction experience. Fred specializes in Southwest Florida, including Home Inspections and Commercial Building Inspections in Fort Myers, Cape Coral, and Naples FL.
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