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.
National Gypsum Sheetrock Gypsum Panel, 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.
Ideal criteria for wall board
The widespread use of drywall for light frame buildings in the U.S. has taught us a lot about drywall's weaknesses and has informed our criteria for an ideal alternative.
I have long had this wish list of criteria for healthy, green wallboard:
- Made from natural materials
- Made with sustainable materials, preferably at least some recycled content
- Low embodied energy (to manufacture the product)
- Completely nontoxic according to German Bau-Biologie standards, which are stricter for health than U.S. green seals
- Moisture and mold resistant, does not wick moisture
- Good moisture transmission, so it dries "in" and "out" (toward the inside and toward the outside of the structure)
- Safer for workers, no exposure to inhalation of crystalline silica dust
- Meets code for wall board, sheathing, subfloors, and roofing
- Meets flammability code requirements without added chemicals
- Pest resistant
- Durable and long lasting
- Easy to install without extensive training
- Comparable in price to drywall and plywood
- Can be plastered or painted
- Widely available and sold locally in most areas of the country
- Made in the U.S.
The (almost) ideal alternative to standard drywall: DragonBoard and JetBoard
When DragonBoard came onto the U.S. market, I got almost everything on my wish list.
- And even though it comes from China and is not yet sold locally in all areas of the country, it is by far the superior choice over all other wallboards on the market, and meets almost all of my criteria for healthy wallboard.
- In fact, DragonBoard is a more than a wallboard; it's also a construction panel, because it can be used in place of plywood for subfloors, exterior sheathing, and other applications.
DragonBoard is made with recycled wood waste dust and minerals, specifically magnesium oxide. The ancient Romans used magnesium oxide to make their super strong cement, which still survives today in ancient Roman ruins.
Since the original publication date of this article, JetBoard http://www.jet-board.com/, made in Texas, has been more recently released in the US, and is available as well. The manufacturer states it is made with the same ingredients as DragonBoard. JetBoard is a great U.S.-made choice .
My colleagues and I have specified DragonBoard and Jetboard for our clients' projects, and we are all very impressed with its healthy ingredients and performance. We had a sample independently lab-tested by a PhD chemist in Germany and it meets all the strictest Bau-Biologie criteria for health. We have not had JetBoard independently tested, but we have compared the ingredients, odor and outgassing time. Both may be better tolerated than drywall, even by most of our highly chemically sensitive clients. I feel great about this product in homes with pregnant women and small babies.
Dust from DragonBoard and JetBoard is not as dangerous to workers when they cut it, as is gypsum drywall, which releases respirable, carcinogenic crystalline silica dust when cut. (Workers should still wear protective goggles and respirators while cutting magnesium oxide board, use dustless cutting methods, and if possible, cut it outdoors, as long as it is completely protected from all sources of moisture.)
The smooth side can be painted, and the rough side can be plastered or tiled with ceramic tile. It should be skim coated if painted.
The downsides to DragonBoard and JetBoard are:
- Most importantly: In some areas of the country and on some projects, depending on factors that include the choice of joint compound or plaster, humidity and temperature variability, settling of the building, earthquakes, and tremors, Dragonboard, Jetboard and other magnesium oxide boards may present cracking problems at the joints or on the plaster/skim coat. This is a real possibility. To avoid possible cracking, consider all factors before choosing magnesium oxide board over conventional drywall for your project.
- Dragonboard must be shipped from China, contributing to a carbon footprint that is higher than U.S.-made JetBoard.
- Both are more expensive than drywall unless you buy a large enough quantity. It may not be cost effective for some smaller projects.
- Both are not readily available in all areas of the U.S., so sometimes it requires more time and cost to order it and have it shipped.
- Although they are compatible with conventional joint compounds, they are not compatible with all nontoxic green drywall joint compounds, particularly Murco-100, as it needs a higher lime content, and especially if applied under natural plasters. (It is highly compatible with nontoxic Keim Dolomitspachtel joint compound, however. For more information on joint compounds, see my article, "Is joint compound really safe? I'm concerned about polyvinyl acetate binders."
Next-best drywall alternative for high-moisture areas: DensArmor Plus Interior Panels
The best and only feature of DensArmor Plus Interior Panels that is superior to conventional paper-faced drywall is that they are mold resistant.
- This is because even though it is a gypsum drywall product, DensArmor Plus is not paper-faced, so it does not provide food for mold.
- Instead, it is faced with a fiberglass mat.Even though it is made of fiberglass, unlike fiberglass insulation, the fiberglass mat does not release hazardous dust.
- DensArmor Plus is also made with binders and other chemicals, but like conventional paper-faced drywall, it is considered low-toxic among healthy building professionals, and does not usually pose health effects, except perhaps to some severely chemically sensitive individuals.
Instead of paper-faced drywall, it's a must for high-moisture areas like bathrooms and kitchens, rooms where water intrusion from leaks and floods is highly likely. It's also great for the interior of lower level exterior walls, where moisture intrusion from poor perimeter drainage and irrigation is also very common.
It is highly available in all areas of the country, and comparatively priced to paper-faced drywall.
DensArmor Plus panels are in the family of Georgia-Pacific DensGlass products, not all of which are biocide-free, so before you purchase DensGlass products, call technical support to check if the product you're interested in is biocide-free or not. As of the date of this article, DensArmor Plus is supposedly not treated with biocides, but it is always best to double-check with tech support at Georgia-Pacific before purchasing, as formulations do change.
Construction alternatives to avoid drywall
Lastly, you could also explore construction alternatives that would obviate the need for drywall/wallboard/construction panels completely, such as Faswall.
These methods require a lot more time, planning, expertise and cost, but they're a great way to go if you can swing it.
For more information:
Read Carl Seville's Q&A "Does DensArmor drywall replace green board? Should I worry about formaldehyde?"