Chinese drywall refers to drywall imported from China (from approximately 2001 to 2007) which contains extraneous metals and minerals, such as sulfur, strontium and iron. Under certain environmental conditions (typically warm, humid climates), the drywall will emit sulfur gasses. These gasses create a noxious odor and corrode copper and other metal surfaces, which can damage one’s air conditioner, electrical wiring, copper plumbing, appliances and electronics. Chinese drywall can also cause adverse health effects, which are primarily irritant and temporary in nature. Long term health effects are unknown.
Not all drywall manufactured in China is defective.
Does your home smell like rotten eggs or ammonia (sometimes a sweetish smell)? Is it more noticeable when entering your home and then seems to dissipate? The level of odor varies greatly in each home as does each person’s ability to detect the odor. Of course, the strength of the odor also depends on how much drywall was used in the home. Significantly, some homeowners report no smell, but their home clearly has Chinese drywall. In short, do not rely on your nose alone, particularly since many develop olfactory fatigue after being exposed to Chinese drywall.
One of the tell-tale signs is corrosion/pitting of the air conditioner evaporator coils (which are located inside the air handler). Many owners are first advised of a freon leak, and as the corrosion progresses, evaporator coils eventually need replacement. An examination of the coils typically (but not always) reveal a black sooty deposit, which may also appear on the freon line. Chinese drywall also corrodes electrical wiring. After turning off the power (please be careful as you could get shocked), check the electrical receptacles in your walls to see if the ground wires are blackened. The wires in this photo have been corroded from Chinese drywall. Since many homes have mixed drywall (i.e., good and bad drywall), not all ground wires will show blackening.
There are also cases that are not clear cut so please consult a qualified inspector.
Signs of an electrical problem include a circuit breaker which frequently needs resetting without an apparent cause (particularly a GFCI or AFCI); lights that flicker without any apparent cause; bright flashes or sparks anywhere in your electrical system (this may indicate arcing conditions in the wiring); buzzing from electrical systems, switch plates, dimmers and outlet covers that are discolored from overheating; and a smell from overheating plastic.
What is the role of strontium? Strontium sulfide, a material that can emit corrosive gases, has been found in levels exceeding 1200 parts per million in Chinese drywall. “It is possible to misclassify homes because of other possible sources of … corrosion such as volatile sulfur compounds from sewer gas, well water, and outdoor contaminants that may enter the home independent of the drywall in the home.” For these reasons, strontium content should not be used as the only identification of tainted drywall.