I bet you never considered drywall to be a potentially toxic product until the Chinese drywall problem raised its ugly head back in 2008. Unfortunately, we’re still not out of the woods for drywall made here or in China. Even today, gypsum board can contain mercury and formaldehyde that in turn off gases into your home.
Mercury Content in Drywall: In 2009 the EPA tested drywall products from both China and the US. Some showed very low levels of 0.0668 to 0.562 parts per million and one American-made product contained a very high level of 2.08 ppm.
The drywall with the highest mercury content was made from synthetic gypsum, which is created from a waste product of coal-burning plants. Some green home certifications specify levels below a specified amount. For example, the Florida Green Building Coalition provides green points for using recycled content drywall throughout the house, if the Mercury levels in the drywall are less than 0.562 parts per million (ppm).
Formaldehyde in Drywall: Also in 2009, EPA testing did find formaldehyde in the core boards of American-made drywall products. The State of California tested gypsum drywall boards for formaldehyde emissions in 2003 and found products emitting more formaldehyde than was safe by the state’s standards. Lovely thought, isn’t it.
I’d like to say that improvements in drywall manufacturing have been made across the board since 2009 reducing or eliminating these toxins, but content still depends on the manufacturer.
In addition to its potentially toxic content, drywall is flammable, the paper coating provides a food for mold, moisture causes it to disintegrate and termites find it quite tasty. In spite of these properties, it has served us well for years.
Magnesium Board to the Rescue: However, we now have a better choice. What if I told you you could contribute to your home’s indoor air quality and durability by selecting a drywall that is completely non-toxic (no off gassing), impervious to moisture and pests, non-flammable and does not offer a food source for mold? I know this sounds too good to be true but it actually does exist and is known as magnesium oxide board.
This product has many uses but is a particularly good choice for showers. Unlike cement board, it has no degree of porousity and the screws can be countersunk.
The downside is cost. Right now it’s running about 3 times more than traditional drywall but obviously, there is no comparison. It is extremely popular for commercial use and in custom residential construction. It’s available in thicknesses ranging from 1/8 inch (easily contoured over curved surfaces) to ¾ inch.
In addition to drywall, the base magnesium product is made into exterior sheathing, soffit material, fascia and lap siding. Very interesting stuff. One manufacturer calls their product Magnum Board. Read more at, http://www.magnumbp.com/products/mb-applications.htm.