Some imported gypsum wallboard products have created problems with issues of off-gassing.
In the United States and in Western Canada, complaints have come up with most from the Southeastern states, where a warm and humid climate seems to encourage the emissions.
Hundreds of millions of sheets of the defective drywall were imported into the United States between 2001 and 2007. It has been reported in as many as 14 states, and may have been used in an estimated 100,000 renovated and newly-built homes, with up to 40,000 in Florida alone.
In addition, an estimated 929,000 square metres arrived in Canada through Vancouver in the same period.
Much of the product imported into Canada was used in the lower B.C. mainland, but some may have reached the Prairies and as far east as Toronto.
The states of Florida (59%), Louisiana (20%), Mississippi (6%) and Alabama (5%) made up 90% of the 3,082 cases reported to the U.S. Consumer Product Safety Commission (CPSC) as of April 2, 2010. More than 700 complaints had been filed with the Florida Department of Health. At that time, it was estimated that from 60,000 to 100,000 homes could have been affected.
In Florida cases, Knauf Plasterboard Tianjin Co. Ltd., part of Knauf Gips KG is the company named as a major producer of imported Chinese drywall. While a number other Chinese companies were suspected of producing defective drywall, Knauf’s name came up most consistently, as the company prints its name on its products. Much of the other contaminated drywall has no markings, making identifying its origin difficult.
Several incidents of gypsum wallboard making homeowners ill and damaging mechanical systems have been reported in British Columbia’s Lower Mainland. The dozen or so instances are linked to far numerous cases in the United States where Chinese drywall is believed to be the culprit.
The building material, thought to have been imported to North America between 2001 and 2007 from China, has been linked with sulphur-like or rotten-egg odours that have resulted in allergy-like symptoms and nose bleeds amongst some homeowners.
The extent of the indoor air quality issues related to this is still unclear. In the United States, the Environmental Protection Agency (EPA) is investigating the problem’s severity. While exposure to sulphur compounds may cause irritation and breathing disorders, the level at which sulphur can be smelled (referred to as the ‘odour threshold’) is very low. In other words, an unfortunate or disagreeable stench does not mean one is being exposed to adverse, health-threatening amounts.
At its worst, this creates a noxious odour, and can result in serious health conditions and illnesses, such as breathing problems, eye irritation, fatigue, dizziness, insomnia, sore throat, bloody nose, and headaches.
The issue is believed to be related to presence of iron disulphide (FeS2 pyrite), which can produce hydrogen sulphide (H2S), carbonyl sulphide, sulphur dioxide (SO2), and carbon disulphide (CS2). These compounds can also corrode air-conditioning coils and other copper-bearing materials, causing them to need frequent replacement. Blackened, scorched wiring behind switch plates and wall plugs have also been repeatedly found. Appliances and other electrical equipment may fail prematurely, and personal jewellery and silverware as well as the wiring in cable televisions and converters can turn black.
It is thought that the problems may be linked to improper storage of the drywall during shipment. Large quantities of Chinese drywall were reputedly kept on sea barges for months, while awaiting permission for importation to the United States. The material could then have developed higher-than-typical density and a higher propensity to off-gas sulphur compounds.
As drywall is usually made of gypsum (i.e. hydrated calcium sulphate), sulphur is one of the main components present in the sample. All drywall has sulphur in its elemental composition; therefore the odour is not explained by an analysis of the total sulphur content alone.
What You Can Do
Houses built or renovated with contaminated Chinese drywall cannot be repaired. The only possible fix for affected homes is to have the owners move out for several months, gut the house and rebuild the interior. Anything inside the house that may have been contaminated by the sulphur gases will also have to be destroyed and replaced.
Industry watchers have estimated that as few as three sheets of drywall in a house can be enough to contaminate it to the point of making it uninhabitable.
House insurance policies do not normally cover environmental issues, and there have been reports of some home insurers refusing to pay for replacement of drywall. In cases like these, homeowners could be facing financial ruin.