Q: Is there such a thing as green drywall? If so, what alternatives to conventional drywall do you recommend? I obviously want to avoid drywall from China, and probably greenboard drywall that has been treated with biocides. What else?
Asked by Jo-Ellen
Editor: Here's what our friends at Green Home Guide say.
Answered by Mary Cordaro, Mary Cordaro, Inc.
Because the word “green” can mean so many things, I'll start with the
- reasons why drywall, often referred to as sheetrock, can be problematic, and then discuss
- my criteria for green and healthy drywall.
- Finally, I’ll review the material types that meet those criteria best.
I’ll also be using the terms “drywall,” “wall board,” and “construction panels,” because there are alternatives to drywall that are made very differently from drywall.
Standard gypsum drywall — okay, but…the down side
Most U.S.-made standard drywall, as long as it is not chemically treated with biocides for mold resistance (as biocides are toxic), is technically a low-toxic material for most individuals, except for some highly chemically sensitive individuals. Compared to other alternatives, it is definitely not 100% nontoxic, as it’s made with a variety of polymers, binders and chemicals, often including very low levels of vinyl acetate monomer, acetaldehyde and formaldehyde.
But with good ventilation, and when correctly and safely installed, as long as the manufacturer has screened for sulfur gases (see below), it rarely leads to serious health problems.
- Workers are required to wear respirators and should use dustless cutting methods to eliminate exposure to carcinogenic crystalline silica in the drywall dust and to cut down on the dust released into the structure.
- I also advise cutting drywall outdoors, not inside the structure, as long as the drywall is protected from all sources of moisture.
- If post-construction cleaning includes a thorough HEPA vacuuming and wipe-down, the construction area is isolated airtight from current living areas, and all exposed HVAC equipment and registers are sealed off airtight, occupants are not typically exposed to the dust.
USG Sheetrock Gypsum Panels, according to the manufacturer, are zero-VOC-emitting, and not manufactured with added formaldehyde. And now, to conserve resources, most of the drywall on the market is made with recycled gypsum and recycled paper.
Blue and green
You are right to avoid the version called “green board,” which is treated with very high levels of toxic antimicrobial biocides and other chemicals.
It’s best to avoid any drywall that is treated with biocides.
The same low-toxicity profile and the caveats that apply to drywall also apply to “blue board,” a type of drywall that is made to be plastered. The paper on the blue board is treated with a detergent that creates a better bond with plaster veneers, and is generally safe for most people, with the exception of some extremely chemically sensitive individuals.
Toxic drywall isn’t just from China anymore
Chinese drywall isn’t alone in its reputation for toxicity. This article from the Sarasota Herald-Tribune describes the recent unfortunate experiences of homeowners whose homes have been contaminated with sulfur gases from U.S.-made drywall, manufactured with toxic synthetic gypsum.
All standard drywall is made with at least some synthetic gypsum now, so before you purchase any standard drywall, check that the manufacturer has screened for the sulfur gases that result from poorly produced synthetic gypsum.
Drywall is "mold food"
When it comes in contact with either liquid water or water vapor, all standard drywall acts like a sponge, sucks up water and moisture vapor readily, and holds onto the moisture. Then, because the drywall surfaces are faced with paper, within 48 hours of becoming wet in the event of a leak or flood, it becomes a perfect meal for mold. In high humidity areas, this can occur over time, if moisture vapor can’t dry fast enough to the interior or exterior of the building, and either builds up on the surface or gets trapped inside the wall cavity.
In addition, with the now-routine recycling of drywall to make new drywall, there’s a possibility that the recycled materials could be harboring dormant mold, which could become activated by moisture vapor under the right conditions. Drywall is incredibly vulnerable to moisture, so if it’s not installed correctly from a building science standpoint, it’s a ticking time bomb, ready to be a growth medium.
To avoid common occurrences of mold contamination in a building, drywall should always be installed as part of a whole-systems approach, using building science procedures that are specific to your climate region, whether it’s for a remodel or new construction.
- It’s essential to plan for moisture, leaks and floods in any project design, but particularly when drywall will be installed.
- For articles and builders’ guides, go to the Building Science Corporation website