Chinese Drywall

Chinese Drywall refers to defective or tainted drywall imported from China from 2001 to 2008 which  emits sulfur gasses which usually (but not always) create a noxious odor and corrode copper and  other metal surfaces, thereby damaging your air conditioner, electrical wiring, copper plumbing,  appliances and electronics.  Chinese drywall can also cause adverse health effects, although experts  disagree whether these effects are merely irritants or present a more imminent or chronic health  hazard.  Not all drywall manufactured in China is defective.

While the material source of the problem is known, a complete understanding of the cause of the  problem remains unknown, which is likely due in part because different mines were involved, there  were different manufacturing processes, and different types of construction and building materials  were used.

Initially, the most common theory was that the drywall was manufactured in gypsum mines in China  which used fly ash, a waste material that is a byproduct from power plants using coal. Samples of  Chinese drywall tested by United Engineering, however, consisted of 5-15% organic material, which  contradicts the theory that Chinese drywall was made of waste from coal fired power plants.   It is  now believed that the tainted drywall from China comes from mined gypsum, not synthetic gypsum  which is made from coal ash.    Mined gypsum contains high levels of strontium, which is visible as  inclusions in electron scanning microscopy.   

Another theory is that Chinese drywall contains bacteria (possibly from the water source used to  manufacturer the drywall) which is degrading iron and sulfur compounds to produce sulfur odors,  although the CPSC's recent report disputes this theory.   

There is no question that the gasses emitted from Chinese drywall corrode copper and metal  surfaces.  Corrosion of electrical wiring may hamper the effectiveness of smoke detectors, which  clearly presents a safety concern.  Low level arcing has also been observed in some homes with  Chinese drywall, which could cause an electrical fire.

Chinese drywall was found by Lawrence Berkley National Laboratories to emit hydrogen sulfide up to 100 times greater than non-Chinese produced drywall. Hydrogen sulfide is a hazardous gas which, in  high concentrations, can be fatal.  There is also a strong association between hydrogen sulfide and  metal corrosion. See CPSC list of drywall manufacturers whose drywall has been found to emit the  high levels of hydrogen sulfide. Analytical testing of Chinese drywall samples have revealed strontium  sulfide, although there remains disagreement regarding whether strontium is a valid marker for  Chinese drywall.  

According to Dr. Patricia Williams, a University of New Orleans toxicologist, highly toxic compounds  have been found in Chinese drywall and prolonged exposure to these compounds can cause serious  problems.   Strontium sulfide may be dangerous to developing children; it affects bone growth.   Chronic exposure to these gases may affect the central nervous system (including visual and sensory  changes), cardiovascular system, eyes, kidneys, liver and skin.   Infants, children, the elderly and  infirm (particularly those with heart and lung disease and diabetes) and pets may have an increased  vulnerability to these gases and the particulates that are released from the drywall.  To date, the  Florida Department of Health still maintains that the levels found in Chinese drywall are not high  enough to present “an imminent or chronic health hazard at this time.”  Many experts disagree. See Florida Department of Health Case  Definition for Drywall Associated Corrosion in Residences.

Guidelines for Chinese Drywall Inspections

Since the identification of Chinese Drywall, Home Check has completed hundreds of Chinese Drywall inspections. In fact, as a policy a Chinese Drywall inspection is included in our standard home inspection for any home that was built between the requisite 2001 and 2008 timeframe. We have been looking for, and find Chinese Drywall on an almost weekly basis for the past several years. Home Check Home Inspections follows the Interim Guidance for Identification of Homes with Corrosion from Problem Drywall as published by the Consumer Product Safety Commission and the Department of Housing and Urban Development.

Identification Method
The identification process is two steps: (1) an initial or threshold inspection to find visual signs of metal corrosion and evidence of drywall installation during the relevant time period, and (2) the identification of corroborating evidence or characteristics.

Step 1: Threshold Inspection

Visual inspection2 must show:
(a) Blackening of copper electrical wiring and/or air conditioning evaporator coils; and
(b) The installation of new drywall (for new construction or renovations) between 2001 and 2008.
A positive result for this step (including both criteria) is a prerequisite to any further consideration.

Step 2: Corroborating Evidence

Because it is possible that corrosion of metal in homes can occur for other reasons, it is important to obtain additional corroborating evidence of problem drywall. Homes with the characteristic metal corrosion problems must also have at least 2 of these corroborating conditions if the new drywall was installed between 2005 and 2008. For installations between 2001 and 2004, at least 4 of the following conditions must be met.

(a) Corrosive conditions in the home, demonstrated by the formation of copper sulfide on copper coupons (test strips of metal) placed in the home for a period of 2 weeks to 30 days or confirmation of the presence of sulfur in the blackening of the grounding wires and/or air conditioning coils;
(b) Confirmed markings of Chinese3 origin for drywall in the home;
(c) Strontium levels in samples of drywall core found in the home (i.e. excluding the exterior paper surfaces) exceeding 1200 parts per million (ppm);
(d) Elemental sulfur levels in samples of drywall core found in the home exceeding 10 ppm;
(e) Elevated levels of hydrogen sulfide, carbonyl sulfide and/or carbon disulfide emitted from samples of drywall from the home when placed in test chambers using ASTM Standard Test Method D5504-08 or similar chamber or headspace testing4;
(f) Corrosion of copper metal to form copper sulfide when copper is placed in test chambers with drywall samples taken from the home.

Chinese Drywall Abatement Inspections

As you know, The State of Florida is one of the hardest hit in dealing with the Chinese drywall issue. We now have recommended protocol for finding the symptoms of drywall; there is even remediation recommendations that prescribe what should be done to move beyond the defective drywall:

Interim Remediation Guidance

This Interim Remediation Guidance for homes with problem drywall calls for the replacement of:
1. all possible problem drywall;
2. all fire safety alarm devices (including smoke alarms and carbon monoxide alarms);
3. all electrical components and wiring (including outlets, switches and circuit breakers); and
4. all gas service piping and fire suppression sprinkler systems.
All testing and remediation work should be conducted in compliance with applicable building codes, occupational safety and health standards, and environmental regulations.

The big question of course, is how do you verify that said remediation has actually been completed? That is where our latest service fits into the picture. Home Check has recently rolled out our – Three Step Chinese Drywall Abatement Inspection which is a report that consists of the following:

Part 1: Initial Chinese Drywall Wall Inspection – Completed to verify symptoms of defective drywall are present.

Part 2: Verification of Removal Inspection – Record with photographic evidence all drywall has been removed and additional remediation recommendations have been completed.

Part 3: Final Inspection – Verification of new drywall installation and replacement of all other recommended components is complete.