How safe is drywall?
GBA Editor
| Posted in Green Products and Materials on
I’m analyzing materials choices for an upcoming project and am wondering how safe drywall is, from an indoor air quality (IAQ) and end-of-life perspective?
Does it off-gas anything notable? Anything at all?
Does synthetic gypsum contain anything (like mercury) that would pollute my site at the end of the building’s life?
I don’t have any particular concerns here, but since I’d be using many pounds of it, I want to make sure I’ve really thought it through. I’m not looking for a “don’t worry” answer. I’m looking for anything at all that might be a concern, so that I can weigh it against alternatives.
Thanks in advance.
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Replies
Tristan,
Before the current Chinese drywall scandal, I never heard anyone raise any IAQ concerns about drywall. If you are unfamiliar with the Chinese drywall scandal, check out these links:
https://www.greenbuildingadvisor.com/blogs/dept/green-building-news/ongoing-chinese-drywall-mess-and-possible-remedy
https://www.greenbuildingadvisor.com/blogs/dept/green-building-news/tainted-drywall-story%E2%80%99s-sturdy-legs
Personally, I think U.S. and Canadian drywall is completely safe. However, if the Chinese drywall scandal has you spooked, plenty of green home builders are very happy with traditional plaster. Remember, though, that these days traditional plaster is often installed over conventional drywall or "lath" that resembles drywall. (If you like old-fashioned building techniques, nothing prevents a builder from installing wooden lath.) Other options include earth-based plasters (often used by builders of adobe or straw-bale homes).
Thanks, Martin.
Interestingly, LEED for Schools has a credit for "Low Emitting Materials—Wall and Ceiling Systems." It does not specifically point to drywall as a high emitter, but this is one of the things that made me think twice about it. Also, the use of synthetic gypsum from coal power plant scrubbers, the same "supply chain" that gives us fly ash with mercury in it.
I did a homemade earthen plaster over wooden lath on my last project. The results are great, but the lath installation was time-consuming, so I'm considering a thinner coat of plaster over drywall for the next time around.
Tristan,
Testing at the Consumer Product Safety Commission and independently at the University of Florida have indicated some sulphur emissions from US-made drywall as well as the Chinese imports, though generally in smaller quantities.
http://www.cbsnews.com/stories/2009/11/23/cbsnews_investigates/main5752469.shtml
My guess is that covering gypsum lath with plaster would seal in any potential out-gassing, but you might want to consider expanded metal lath as a plaster substrate. It also has the advantage of being able to be installed on curved walls and window returns.