Corrosive Drywall Syndrome

1. The home was constructed or renovated with new drywall since 2001.
2. Observed corrosion of air conditioner evaporator coil exemplified by black corrosion on copper tubing components.  The corrosion can result in refrigerant leakage making it impossible to cool the home requiring coil replacement.  Coil failures indicative of this problem typically occur every 6-14 months
3. Observed metal corrosion, indicated by blackening of one or more of the following:
   • copper wires, ground wires, and electrical connectors
   • un-insulated and un-coated copper pipes and fittings
   • chrome-plated bathroom fixtures
   • silver and copper jewelry
   • mirror backing in bathrooms

(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.

1. Observed markings on the back of drywall indicating the country of origin is China.
2. Objective analysis of drywall in home finds Strontium levels exceed 2,000 mg/kg (ppm), indicating the gypsum used in the drywall was probably mined in China.
3. If you have met the criteria for “possible case” and answered yes to at least one of the above indicators in Criteria 2, the home meets the criteria for “probable case”.  These criteria do not confirm that the drywall causes corrosion. Identifying the origin of the drywall is considered a screening tool for suspect drywall, but confirmation requires analysis described in Criteria 3.

(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 thepresence of sulfur in the blackening of the grounding wires and/or air conditioning coils;

(b) Confirmed markings of Chinese 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.

1. Elemental sulfur (Orthorhombic sulfur, cyclooctasulfur, S8) content of gypsum core exceeding 10 mg/kg (ppm), indicating the gypsum in drywall samples from the home contains the source material that is believed to contribute to the reduced sulfur gasses emitted from corrosive drywall. Analytical methods commonly used for this include GC/ECD, GC/MS, or HPLC.
2. Laboratory analysis of suspect drywall headspace for reduced sulfur gas emissions (H2S, COS, CS2) indicating drywall samples from the home emit reduced sulfur gasses capable of causing copper corrosion. Analytical methods commonly used for this include GC/SCD.6 Results that are indicative of corrosive drywall must be established by each laboratory based upon internal procedures, comparison to control samples, and validated methods.
3. Qualitative analysis of suspect drywall for its ability to cause corrosion/blackening of copper under controlled conditions, indicating drywall samples from the home emit gasses capable of corroding copper.  Results that are indicative of corrosive drywall must be established by each laboratory based upon internal procedures, comparison to control samples, and validated methods.