Drywall Hazard Spectrum

Individual products can vary significantly in their chemical content, however there are some types of drywall that generally have less hazardous impacts than others. HBN ranks types of drywall materials on a simplified spectrum below.[1] Products in the green categories are typically better options than those in the orange or red, and products in the yellow categories are generally less preferable than those at the top, but are better choices than those at the bottom.

Drywall use is prevalent in U.S. construction. Nearly 24 billion square feet of gypsum board are sold in the U.S. each year.[2] Drywall, also known as gypsum board or wallboard, is made up of a mineral core of gypsum and additives, sandwiched between facing materials. Fire-resistant panels, like Type X and Type C, and mold or moisture resistant panels contain additional additives like glass fibers and antimicrobials. The facing materials are most commonly paper but can also include fiberglass mat, aluminum foil, or vinyl for specialty applications.[3]

HBN’s guidance on the selection of healthier drywall focuses on the gypsum itself. Gypsum can be natural (mined from the earth), or synthetic (from coal-fired power plants). The type of gypsum available can vary by region, company, and manufacturing plant. Increasingly, drywall manufacturers have shifted toward the use of more synthetic gypsum, also called FGD or flue-gas desulfurization gypsum.[4] This shift has lifecycle impacts in the form of increased mercury emissions from drywall plants. See our blog post for additional information.

Here are some general rules of thumb to use when choosing drywall materials:

  • Prefer drywall with the lowest amount of pre-consumer recycled content you can find. This is because FGD gypsum is classified as pre-consumer recycled content and is identified this way in most product literature. Technical Data Sheets, LEED sheets, recycled content certifications, or other product literature often provide this information for each of the company’s facilities.
  • Look for drywall with post-consumer recycled content when you can. Currently, most post-consumer recycled content in drywall comes from the paper facings. These facings make up about 3-8% of the product weight. In addition, construction trim scrap represents a huge potential recycling stream - an estimated ten percent of the drywall needed for a project ends up as scrap.[5] While not yet widespread, products made with recycled trim scrap are available in some regions. There are existing programs in the Pacific Northwest and Europe, and new innovations and partnerships are being developed by the Building Product Ecosystems’ (BPE) collaboration. Through the BPE Closed Loop Wallboard Collaborative, efforts are underway to collect drywall cut-offs from worksites and reprocess them into new drywall. Be on the lookout for the availability of drywall with this additional post-consumer content in the future, and consider how your projects can separate drywall cut-offs for recycling.
  • Avoid using mold resistant drywall where not needed. Mold resistant drywall may be deemed necessary in certain applications, such as areas that experience periodic elevated humidity, like bathrooms. Because these products contain added antimicrobials which may be hazardous, avoid using them where they are not needed, such as living rooms and bedrooms.
  • Prefer products with a CDPH emission certification. Ask for products certified to the most protective, residential scenario.[6] The California Department of Public Health (CDPH) Standard Method for Testing and Evaluation of VOC Emissions imposes limits on 35 specific VOCs including formaldehyde, which has previously been identified in emissions from some drywall.[7]
  • Prefer products with full disclosure of content (including antimicrobials for mold resistant products) and associated health hazards through the industry’s collaborative, user-designed open standard, Health Product Declaration (HPD). Many drywall manufacturers are active in the transparency movement. Prefer products with HPDs that disclose all content to 100 parts per million (ppm) or are Third-Party Verified. Learn more about why transparency matters and find resources here.
  • Use lightweight boards when possible to help cut down on impacts by reducing the amount of gypsum that is used, as well as the energy and water consumed during manufacturing.[8]

 

See our blog post on drywall accessories for information and recommendations on joint compound and sealants.

Drywall made with natural gypsum is not without human and environmental concerns. Mining can have environmental impacts of its own and natural gypsum is a non-renewable resource. This is one reason to decrease the amount of gypsum waste on projects and to support closed loop recycling efforts like the Building Product Ecosystem Closed Loop Wallboard Collaborative.

Additives in gypsum drywall are typically of low hazard. Much like soil and other natural geologic materials, natural gypsum does contain metal impurities. The quantities of these impurities are typically below background levels found in soil.[9] Crystalline silica is also present as an impurity and is considered a carcinogen when inhaled. Drywall manufacturers report that respirable crystalline silica levels are below OSHA established limits for standard methods of cutting drywall for installation, but jobsite industrial hygiene testing may be required.[10]

Mold exists naturally in the world and can be found almost everywhere, including indoor environments.[11] It requires both a food source (organic matter) and moisture in order to grow. When mold does grow in buildings, it can lead to health problems for occupants such as stuffy nose, wheezing, or asthmatic reactions.[12] Preventing the growth of mold in buildings is important for occupant health and the integrity of the building.

Many building products can provide nutrients that allow for mold growth. In drywall, cellulose and starch found in paper facings and the core of drywall panels can serve as food for mold.[13] Drywall can be made more mold resistant by removing the food sources for mold (for example swapping paper facing for fiberglass facing) or by adding biocides to the core and paper facing.[14]

Paper-faced mold and moisture resistant drywall panels, (the latest iteration of previous moisture resistant panels, sometimes called greenboard), are often used in interior applications where there is periodic elevated humidity, such as bathrooms or laundry rooms. They are not intended for use where there is direct exposure to water or in areas with continuous high humidity. Mold resistant drywall with a fiberglass matt facing can be used for additional applications, such as behind tile in wet areas (tub and shower) where allowed by code, and when drywall is installed before the building is fully enclosed.[15] Both paper-faced and fiberglass-faced mold resistant products commonly contain additives to help repel moisture as well as antimicrobial additives.[16] The specific antimicrobial additives used are not typically disclosed, but antimicrobials that have been identified for use in drywall can be carcinogens and mutagens and most are considered toxic to aquatic life. 

Keep in mind that mold resistant drywall is not “mold-proof.”[17] Use best practices for material handling during construction and implement proper moisture control and ventilation in buildings as primary mold prevention strategies. For applications where mold resistant drywall is needed, ask manufacturers to fully disclose product content, including antimicrobials, and associated hazards through Health Product Declarations. Because of the potentially hazardous antimicrobials, and the fact the mold resistant drywall costs more than standard drywall,[18] avoid using mold resistant drywall when it is not necessary.

Synthetic gypsum, also known as FGD gypsum is produced from pollution control devices at coal-fired power plants. Flue-gas desulfurization (FGD) units generate FGD waste which is further processed into FGD gypsum.[19] These pollution control systems reduce the emissions of mercury and other pollutants from the power plant by capturing them in FGD gypsum and other pollution control residues like fly ash.[20] When FGD gypsum is then used in drywall manufacturing, it can shift the mercury emissions from power plants to the drywall manufacturing process.[21]

According to data reported to the EPA by drywall manufacturers, mercury emissions from drywall manufacturing facilities have increased as more FGD gypsum is used. There are a lot of factors that can impact the amount of mercury found in both natural and FGD gypsum and the amount of mercury released during drywall manufacturing, but overall, the increasing use of FGD gypsum has led to increased mercury emissions from drywall manufacturing facilities. See our blog post for additional information. Mercury is highly toxic, and because it is persistent in the environment, it can travel large distances and have far reaching impacts on human and environmental health. 

The potential impacts on building occupants are unclear. A limited dataset suggests that the use of FGD gypsum in drywall may result in higher levels of mercury in the finished drywall than with mined gypsum.[22] In both cases, the amount of mercury in finished drywall has been found to be very small. More testing of potential mercury emissions from drywall is needed to understand the potential impacts during use.

Prefer drywall products with the lowest amount of FGD gypsum (pre-consumer recycled content) available. If you must use products made with FGD gypsum, ask manufacturers to publicly disclose how they monitor and limit mercury content and emissions.

As with drywall made with natural gypsum, mold resistant panels are less preferred to regular panels in areas that do not have elevated humidity.

Prefer drywall products with the lowest amount of FGD gypsum (pre-consumer recycled content) available. If you must use products made with FGD gypsum, ask manufacturers to publicly disclose how they monitor and limit mercury content and emissions.

For applications where mold resistant drywall is needed, ask manufacturers to fully disclose product content, including antimicrobials, and associated hazards through Health Product Declarations. Because of the potentially hazardous antimicrobials, avoid using mold resistant drywall when it is not necessary. 

Endnotes

[1] Unless otherwise noted, product content and health hazard information is based on research done by Healthy Building Network for Common Product profiles, reports, and blogs. Links to the appropriate resources are provided.

[2] Based on annual sales between 2015-2019. USGS. “Gypsum Statistics and Information.” Accessed June 11, 2020. https://www.usgs.gov/centers/nmic/gypsum-statistics-and-information.

[3] “DensArmor Plus Abuse-Resistant Interior Panels.” Georgia-Pacific Building Products. Accessed June 25, 2020. http://buildgp.com/product/densarmor-plus-fireguard-abuse-resistant-interior-panels/.; “Gold Bond Brand Durasan Prefinished Gypsum Board.” National Gypsum, February 2015. https://nationalgypsum.com/File/110705.pdf.; “Health Product Declaration: USG Sheetrock® Brand Foil-Backed Gypsum Panels.” USG, August 15, 2018. https://hpdrepository.hpd-collaborative.org/repository/HPDs/publish_90_USG_Sheetrock_Brand_Foil_Backed_Gypsum_Panels_1534346717.pdf

[4] Based on annual survey results from the American Coal Ash Association. The annual use of FGD gypsum in drywall has increased from about 3 million to 12 million tons between 2000-2018. See ACAA. “Coal Combustion Products Production & Use Statistics.” Accessed June 25, 2020. https://www.acaa-usa.org/publications/productionusereports.aspx

[5] “Recycling - Gypsum Association.” Gypsum Association. Accessed June 25, 2020. https://gypsum.org/recycling-gypsum-wallboard/.

[6] California Department of Public Health (CDPH) Standard Method for Testing and Evaluation of VOC Emissions (formerly called California 01350) uses a small scale chamber test to determine emission of VOCs from products. Results of the small scale testing are modeled to represent different real world scenarios. The most protective is the residential scenario, and this should be preferred if available. Most certifications now available are for the less protective school or private office scenarios. Programs that certify the CDPH Standard Method or a variation of the standard include GreenGuard Gold, SCS Indoor Advantage Gold, and Berkeley Analytical Clear Chem.

[7] “Drywall Sampling Analysis.” United States Environmental Protection Agency, May 7, 2009. https://pharosproject.net/uploads/files/sources/1828/epa-testing-2009.pdf.; Alevantis, Leon. “Building Material Emissions Study.” California Integrated Waste Management Board, November 1, 2003. https://www2.calrecycle.ca.gov/Publications/Download/582

[8] “Gypsum Board.” Architecture 2030 - Carbon Smart Materials Palette. Accessed July 1, 2020. https://materialspalette.org/gypsum-board/

[9] Yost, Lisa J., Scott S. Shock, Stewart E. Holm, Yvette W. Lowney, and Jessica J. Noggle. “Lack of Complete Exposure Pathways for Metals in Natural and FGD Gypsum.” Human and Ecological Risk Assessment: An International Journal 16, no. 2 (April 7, 2010): 317–39. https://doi.org/10.1080/10807031003670352.; Data shared by project team from Wagner, Danielle, Zhongqi Cheng, Amanda Kaminsky, Sydney Mainster, Geoffrey Brock, Ronald Spalter, and Catherine Bobenhausen. “Safeguarding Our Resources And Indoor Air Gypsum Wallboard Closed-Loop Recycling In An Era Of Increased Chemical Transparency.” Boulder, Colorado, 2015.; and “Comparison of Coal Combustion Products to Other Common Materials.” Electric Power Research Institute (EPRI), September 30, 2010. https://www.epri.com/research/products/000000000001020556

[10]  “OSHA Crystalline Silica TechUpdate: CertainTeed Gypsum Board Products.” CertainTeed, October 18, 2017. https://www.certainteed.com/drywall/osha-crystalline-silica-techupdate-certainteed-gypsum-board-products/.;  “Safety Data Sheet: SHEETROCK® Brand AR Gypsum Panels FIRECODE® Core.” USG, March 24, 2017. https://www.usg.com/content/dam/USG_Marketing_Communications/united_states/sds/usg-sheetrock-abuse-resistant-firecode-core-gypsum-panels-sds-en-54000002006.pdf.; “Safety Data Sheet: Gypsum Wallboard Panels.” American Gypsum, February 25, 2020. https://www.americangypsum.com/sites/default/files/documents/SDS_1.pdf.; “2015 Study on Respirable Crystalline Silica Emissions When Sizing Drywall.” Gypsum Association. Accessed June 25, 2020. https://gypsum.org/2015-study-on-respirable-crystalline-silica-emissions-when-sizing-drywall/

[11] “Mold - General Information - Basic Facts.” Centers for Disease Control and Prevention (CDC), December 17, 2019. https://www.cdc.gov/mold/faqs.htm.; Parrott, Kathleen. “Mold Basics.” Virginia Cooperative Extension. Accessed June 25, 2020. https:////www.pubs.ext.vt.edu/content/pubs_ext_vt_edu/en/2901/2901-7019/2901-7019.html.; “Ten Things You Should Know about Mold.” Collections and Lists. United States Environmental Protection Agency, October 22, 2014. https://www.epa.gov/mold/ten-things-you-should-know-about-mold

[12] “Mold - General Information - Basic Facts.” Centers for Disease Control and Prevention (CDC), December 17, 2019. https://www.cdc.gov/mold/faqs.htm

[13] Dedesko, Sandra, and Jeffrey A Siegel. “Moisture Parameters and Fungal Communities Associated with Gypsum Drywall in Buildings.” Microbiome 3 (December 8, 2015): 71–71. https://doi.org/10.1186/s40168-015-0137-y.; Lstiburek, Joseph, Terry Brennan, and Nathan Yost. “RR-0208: What You Need to Know About Mold,” January 15, 2002. https://www.buildingscience.com/documents/reports/rr-0208-what-you-need-to-know-about-mold/view.

[14] Dean, Timothy, and Doris Betancout. “Microbial Resistant Test Method Development.” United States Environmental Protection Agency Office of Research and Development, August 2015. https://nepis.epa.gov/Exe/ZyPDF.cgi/P100U64N.PDF?Dockey=P100U64N.PDF

[15] “Submittal Sheet: USG SheetRock® Brand Glass-Mat Panels.” USG, April 2020. https://www.usg.com/content/dam/USG_Marketing_Communications/united_states/product_promotional_materials/finished_assets/usg-sheetrock-brand-glass-mat-panels-mold-tough-ar-firecode-x-submittal-WB2750.pdf.; “Submittal Sheet: DensArmor Plus® Interior Panels.” Georgia Pacific, January 2014. https://buildgp.com/wp-content/uploads/2018/11/PDF-DensArmor-Plus-Interior-Panels-Submittal.pdf?x14232

[16] “Health Product Declaration: Sheetrock® Brand Glass-Mat Panels Mold Tough® AR Firecode® X.” USG, June 18, 2019. https://hpdrepository.hpd-collaborative.org/repository/HPDs/publish_90_Sheetrock_Brand_Glass_Mat_Panels_Mold_Tough_AR_Firecode_X.pdf

[17] Manufacturer literature states that their mold-resistant products provide increased mold resistance versus standard drywall products. The mold-resistance claims are most commonly based on results of testing per ASTM D3273, “Standard Test Method for Resistance to Growth of Mold on the Surface of Interior Coatings in an Environmental Chamber.” Manufacturers note that this testing is done under controlled laboratory conditions and actual real world conditions may vary. They also note that the most effective way to avoid mold and mildew is to avoid exposure to water during storage, installation, and following installation, using good design and construction practices. See: “Submittal Sheet: MBloc® With Mold & Moisture Resistance.” American Gypsum, February 2019. https://www.americangypsum.com/sites/default/files/documents/M-BlocSubmittal.pdf.; “Submittal Sheet: Certainteed M2Tech® Regular & Type X Gypsum Board.” CertainTeed, February 2017. https://www.certainteed.com/resources/CTG_2403_M2Tech_DSS_Eng.pdf.; “Submittal Sheet: Mold Curb® Plus Mold & Water Resistant, Regular, Type X.” Pabco Gypsum. Accessed June 25, 2020. https://www.pabcogypsum.com/sites/default/files/PABCO_Mold_Curb_Plus_Submittal.pdf.; “Submittal Sheet: Mold Defense®.” Continental Building Products, December 2019. https://continental-bp.com/content/uploads/2019/12/2019-Mold-Defense-Submittal-US.pdf.; “Submittal Sheet: ToughRock.” Georgia Pacific, January 2014. https://www.buildgp.com/wp-content/uploads/2018/10/ToughRock-Mold-Guard-Submittal.pdf

[18] A review of drywall costs from Home Depot, Lowes, and Menards on June 9, 2020 indicates that mold and moisture resistant drywall is commonly about 40-50% more expensive than standard drywall, and fiberglass faced drywall adds even more cost. Also see: “Drywall Installation Cost by Type.” Accessed June 25, 2020. https://drywallpriceguide.com/drywall-prices-by-type/

[19] Coal Combustion Residual Beneficial Use Evaluation: Fly Ash Concrete and FGD Gypsum Wallboard.” United States Environmental Protection Agency: Office of Solid Waste and Emergency Response and Office of Resource Conservation and Recovery, February 2014. https://www.epa.gov/coalash/coal-combustion-residual-beneficial-use-evaluation-fly-ash-concrete-and-fgd-gypsum-wallboard

[20] Kosson, D., F. Sanchez, P. Kariher, L.H. Turner, R. Delapp, and P. Seignette. “Characterization of Coal Combustion Residues from Electric Utilities – Leaching and Characterization Data.” United States Environmental Protection Agency, December 2009. https://nepis.epa.gov/Exe/ZyPDF.cgi/P1007JBD.PDF?Dockey=P1007JBD.PDF

[21] See our blog post, “Selecting the Wrong Drywall Could Introduce Mercury into the Environment,” for a detailed analysis. 

[22] “Coal Combustion Residual Beneficial Use Evaluation: Fly Ash Concrete and FGD Gypsum Wallboard.” United States Environmental Protection Agency: Office of Solid Waste and Emergency Response and Office of Resource Conservation and Recovery, February 2014. https://www.epa.gov/coalash/coal-combustion-residual-beneficial-use-evaluation-fly-ash-concrete-and-fgd-gypsum-wallboard.; Compiled data in Appendix A includes three studies with limited test data on the mercury concentration in FGD gypsum drywall and/or natural gypsum drywall. Concentrations reported were: 0.07-1.4 ppm in FGD gypsum drywall and 0.0007-0.0011 ppm in natural gypsum drywall. One study looked at emanation rates of mercury from drywall, which were higher from panels with higher mercury content (those made with FGD gypsum). 

Last updated: July 6, 2020