There's a thread about Chinese drywall on the LBN forum. In it there's a lot of strange information, such as the concept greed brought that rock to our shores. Someone in that thread urged me to write an article about drywall. Without further ado, here we go.
Begin at the beginningIn 1894, Augustine Sackett patented "Sackett Board." He interleaved wool felt paper with gypsum plaster to produce boards 36 inches square by 1/4" thick. Sackett tried selling it as a wall finish (similar to what drywall is used for today) to people who really hated using it--the edges crumbled and it looked terrible. Then a plasterer thought, "what would happen if we put Sackett Board on the wall and plastered over it?" It turned out to install faster than wood laths, and took plaster better. Sackett was soon making all the board he could. In 1901, Sackett was making almost five million square feet of board.
A slew of innovations followed until, at long last, they came to the board we know today: it's four feet wide, has wrapped, tapered edges, is "air entrained" to make it lighter, and comes in four basic thicknesses: 1/4", 3/8", 1/2" and 5/8" with 1/2" the most commonly used. It is faced with either recycled paper or fiberglass. It was named "drywall" to differentiate it from a plastered "wet wall," and it's also called "plasterboard" because it's made from plaster.
It got popular during World War I, and the Army is to thank for this. The Army wanted naturally fire-resistant and fireproof building materials for barracks construction, and drywall delivered. When these contractors worked on civilian projects, they chose drywall: they knew it and liked it, and continued to use it. Later, the post-WWII building boom permanently cemented (pun not intended) drywall's place as a choice building product.
How drywall worksI know, I know..."screw it to the wall and mud the joints and screwholes." Now let's talk fire performance.
Drywall protects from fire because each gypsum molecule is bound to two water molecules. When the stuff is exposed to fire, the gypsum releases the water, which helps to retard the fire. So...if your house catches fire, replace all the drywall, m'kay?
Tell me about gypsumGypsum is the heart of drywall. It's calcium sulfate. Bear that in mind: there's SUPPOSED to be sulfur in it, but it's supposed to be bound up with calcium and oxygen. Two popular places to get this are by mining it and by recovering it from coal-fired power plants. By cleaning the ash of free sulfur and such wonderful contaminants as mercury and arsenic, a wonderfully pure gypsum can be recovered from coal smoke. Some places recover it because it's legally required, others because drywall companies will buy it. Go back two sentences and read the first four words. Commit them to memory.
Now tell me about Chinese drywall
During the Bush administration, two factors collided to cause a drywall shortage in the US. First was the building boom, where people were throwing up houses as fast as they possibly could, (Most observers don't add house flippers to this problem; perhaps they should. There were a lot of people flipping houses then and they were using a lot of drywall.) The second were the hurricanes along the Gulf Coast. The only way many builders could complete projects on time was to purchase foreign drywall--and most of it came in from China.
The drywall was made out of improperly cleaned flue-sourced gypsum. The free sulfides stayed in the material and eventually started going into the air, where they corrode metals and cause health problems.
Is Chinese drywall a threat to the US gypsum industry?
A container of dtywall has 680 sheets of board in it and costs from $5000 to $7500 to move by ship from China to the US. You can walk into any Home Depot in America and buy a sheet of drywall (which, incidentally, is proudly made in the USA) for $5.62. At that price, one container of drywall will sell for $3821.60--a net loss of $1178.40 not counting the cost of making the board, profit for the manufacturer, trucking it to the port, trucking it to a US warehouse then finally carrying it to a store and selling it. (And forget the idea you can just put more board in the container. Twenty lifts of drywall weigh 40,800 pounds. Add the container and you're very close to being at maximum legal weight for a truck on American roads.) People go into business to make money, so no you won't see this stuff darken our doors again.
How to tell you have itIf you have a garage check it. Most people just firetape garage walls and leave them, so look at both sides of it. You're looking for the words Made In China or Knauf Plasterboard Tianjin (KPT). A lot of times it's on the back of the sheet. Sometimes it's not there, so go to alternate means: check copper items like wiring, plumbing and air conditioning condensers.
I can't answer what to do if you have it. Gutting the house is too expensive. Sellling is a minefield. Suing is a worse one. Walking away from the house will destroy your credit. As I said, there's no good answer, sorry.
References:
Walls and Ceilings Online, http://www.wconline.com/Articles/Column/090578779d768010VgnVCM100000f932a8c0____
The author of this piece was in the building materials trade for six years, including the period when the Chinese drywall was coming into the US market.
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