Tainted Drywall

In a recent inspection (ocean front condo) I came across heavily darken coils in the air handler indicative of possible tainted drywall but no other indication any place else. All the ground wiring looked good and all the copper tubing looked good. I even pulled out the refrigerator and removed the back plate to look at the copper in the refrigerator and it looked good. I later found out that in previous inspections of other units performed by a company known to do “tainted drywall inspections” in the local area they found the same conditions and in their opinion that was not sufficient evidence of tainted drywall.

My question is: what else could cause the copper coils to turn black in the absence of tainted drywall?

Attach is a picture of the coils. Thank you in advance for your input.

Tainted drywall could have just been used only in the area near the HVAC, and not throughout the whole home. Only way to know for sure is to have samples of the drywall in rooms professionally tested. Also, people along ocean fronts leave doors/windows open constantly, and air out homes on living levels, and not lower levels.

The salt air from the ocean is certainly one consideration. The air handler has an open return and it is located in a utility closet along with the water heater and all the main copper pipes coming into the unit and nothing else shows any evidence of anything. The water heater pipes just 2 feet away from the air handler look like the day they were installed.

Another consideration would be any alloys mixed with the copper in the air handler. Does that sounds like a plausible explanation?

one thing you should consider is that the HVAC coils are wet during operation. The other copper items are not.

More air passes over the HVAC piping than the other copper items.

I had two inspections last week both of which contained suspected corrosive drywall syndrome. The first home was constructed in 2001 and had all of the signs, corrision at the evaporator coil, wire at the service panel, and all of the outlets that i opened up. the second home only had corrision in the bathroom plumbing,piping,and electrical components. Both homes had an unusual foul odor. as posted earlier the only way to know for certain is to have physical s

amples lab tested

What year was the condo built? Any obvious renos?

The small section of discoloured copper at the coil may have become that way from other conditions. The copper in the right of the picture looks clean and good. If there was a major amount of H2S and other sulfur compounds in the air, I would assume that all the copper in this location would be discoloured.

I certainly hope the buyer/buyers in these two instances immediately left and looked elsewhere for a home. After seeing the corrosion/damage in your pictures, that’s all the evidence I would need as a buyer to walk away. Thanks for sharing.


Oh yes both clients are back out shopping

Mark, I went to do an inspection in a home down here in Homestead built in 2006. The neighborhood was all ready in the news for having the tainted drywall. They went in hoping for the best but expecting the worst.

The very first electrical switchplate I removed from the wall next to the front door showed the discolored copper. The wife immediately told her husband, the agent and myself, “okay that’s it! Inspection is over”! I actually checked a couple other locations and they were contaminated as well. They are negotiating a new deal on another home and will call me once they’re ready.


I would compare copper wiring in outlets near AHU to those in several locations in house. You may get lucky and find contamination in only one location or perhaps even the AHU box. The AHU may have leaked water at some point requiring the immediate drywall to be replaced. If this happened during the drywall shortage (hurricanes) when Chineese drywall was imported, it may just be a couple of gyp boards at AHU. Probably not, but possible.

Looks kinda normal to me.

Question to those experienced with this problem…

Once the ‘chemical reaction’ (from the tainted drywall) begins, does the ‘reaction’ continue even if the source problem is remediated?

Here’s what I’m thinking, based upon the information provided…

Could this have begun while the HVAC unit was in storage, and progressed after being installed? If so, the warehouse could have been the source of the contaminate. This would explain why nothing else in the unit exhibited signs of the reaction, and why other Condo’s had the same issue. All HVAC units from the same warehouse, installed in the same timeframe.