Chinese Drywall??

[jahilliard]

I was asked to do an inspection on a home that is known to have Chinese drywall. I am aware of the effects on the copper conductors within these homes but I am not aware of any evidence that the existing wiring is in need of being replaced or if the "discoloration" or oxidation or whatever it is exactly that causes the black color, is just simply a visual issue. Is there any research or articles about findings of any kind in these chinese drywall houses that have determined the existing wiring to be safe as it is or does it need to be replaced where exposed or completely replaced??

 

[gadfly56]

I was asked to do an inspection on a home that is known to have Chinese drywall. I am aware of the effects on the copper conductors within these homes but I am not aware of any evidence that the existing wiring is in need of being replaced or if the "discoloration" or oxidation or whatever it is exactly that causes the black color, is just simply a visual issue. Is there any research or articles about findings of any kind in these chinese drywall houses that have determined the existing wiring to be safe as it is or does it need to be replaced where exposed or completely replaced??

A quick trip around the web seems to indicate the consensus is replace the wiring. The problem is that the copper sulphide "discoloration" is about 5 orders of magnitude less conductive than pure copper. As corrosion progresses, more wire surface is exposed, leading to more corrosion, etc. Unless you want to clean every conductor and confirm that the gauge is still good I wouldn't keep it. You could risk an overtemperature condition from what is similar to a loose or high resistance connection.

 

[jahilliard]

Without reading lengthy internet articles explaining exactly what happens to the copper, are you able to briefly explain what's going on? For example, in your opinion, would an answer be to remove only the exposed copper and use the copper that has been protected by insulation the entire time. I have been informed the house has had all chinese drywall removed and replaced, seemingly the copper should no longer continue to "discolor" if the effected copper is removed. I am completely ASSuming, and I definitely do plan to read more about this in order to provide a more definite decision to provide the mortgage company, but I encourage any feedback above and beyond that, thanks!

 

[gadfly56]

The drywall emits hydrogen sulfide (H2S) gas. The sulfer reacts with the copper to form a copper sulfide film which is significantly less conductive than copper. Corrosion slows as the film thickens, until the film fractures due to internal stresses brought about by the fact that Cu2S molecules and Cu atoms have different crystal lattice spacing. This exposes more Cu to corrosion. If left long enough you might wind up with a connection that is pure Cu2S. Don't forget that this is happening at the device terminals as well.

We all know that plastic insulation is pervious to water and gases. It's possible that the H2S has diffused through the plastic and is attacking the copper along the entire length of wire, although at a very much slower rate. The H2S is going to diffuse back out of the jacket as slowly as it diffused in, so even with new dry wall you may (and I stress may) still have corrosion occuring in your nice "clean" remodel. What is the H2S is doing to the insulation by the way? I don't know, but who wants to find out the hard way?

Where does the theoretical intersect with the practical? I don't know. Someone would have to run a bunch of tests to see what the reality of the situation is.

Even if you strip back the last 4-6" to be "safe", you probably don't have that much slack in your wire runs. Do you cut in a junction box somewhere and put a blank finish plate on it?

In a nutshell, I'd say don't ask for trouble 'cause the universe will hand you all you want and then some!

 

[dhamman]

The most compelling statement came out last week when the consumer product safety commission stated that wiring should be replaced in these homes. Our local city inspector who was allowing joints to be cleaned and the wire left in place immediately stopped that.
Our County inspectors would not state how to treat these homes they asked for a stamped engineers statement of how to repair and since there is currently no approved method of remediation and no engineer will do that they get rewired. If you look at the cost to remove and replace drywall, insulation, HVAC, wiring devices and fixtures it is not that much more to replace the romex. The jobs that have insurance companies involved get rewired as they don't want to hear a couple years down the road they should have replaced the wire and do it all over again.

So for us being in the #1 foreclosure capital (SW Florida) we will take the work.

We have seen the corroision (blackening) travel up the fine stranded wire on the Arc Fault nuetral 8" or more. Does not seem to travel on the solid conductors in the romex.

http://www.chinesedrywall.com/

Dave

 

[bphgravity]

Please see the CPSC Drywall Remediation Guide attached.

 

[bphgravity]

FYI:

Chinese company to fix 300 homes, possibly thousands more damaged by corrosive drywall.

CAIN BURDEAU
Associated Press Writer


October 14, 2010
NEW ORLEANS (AP) — A Chinese drywall manufacturer, along with suppliers, builders and insurers, agreed Thursday to repair up to 300 homes in four states and possibly thousands more damaged by corrosive drywall.

In this pilot program, up to 300 homeowners in Florida, Louisiana, Alabama and Mississippi whose homes had drywall manufactured by Knauf Plasterboard Tianjin Co. will get their homes fixed, lawyers said. Homeowners in Texas, North Carolina and Virginia could be added soon.

Knauf and the other companies have agreed to replace drywall, wiring, fire and alarm systems, and fixtures in damaged homes. Many more of the 2,000 to 3,000 homes built with Knauf drywall might be fixed under similar terms if the pilot program is successful.