Waterproofing is one of those underappreciated building materials that very few people think about until it fails to do its job of keeping water and moisture out. It is an essential component of a structure, as water is a highly destructive element when it gets into places it's not meant to be, causing deterioration, impacting indoor air quality due to mold and mildew, and creating all sorts of other damage to property and human health. It is one of the most important products used on a building.
Even more underappreciated and unknown are the impacts from the chemicals and materials used in making various waterproofing products, and the havoc some create for human health and the environment.
Some of you have considered impacts of the installers and building occupants, and you assessed whether the products off-gas volatile organic compounds (VOCs). Perhaps you have wondered whether they contain chemicals that mimic hormones (aka endocrine disrupting) like phthalates that are devastating to children's health, as well as for adults.
While these are very important considerations, it is vital that we also look beyond the installers and building occupants and examine how these materials broadly impact our overall health and the environment.
Healthy Building Network (HBN) recently highlighted the true cost of toxic materials. This work emphasized the numerous ways select materials have an impact during raw material extraction, product manufacturing, installation and end-of-life. HBN’s Product Guidance incorporates some of these often overlooked considerations, in addition to the impacts on those installing and living with these materials. We recently added information on waterproofing and dampproofing. Take a look at some examples of how broader life-cycle considerations were incorporated into our recommendations.
New! Waterproofing and Dampproofing Guidance
The figure below is a snapshot of our hot-off-the-press waterproofing and dampproofing product guidance. We encourage you to select product types that are yellow or above to decrease toxic chemical exposures to people and the planet. Products in green are the best options while products in red should be avoided. Those in-between provide intermediate, and meaningfully better options from a health hazard perspective as you advance up the color rankings. In short, strive to get out of the red-zone.
Use mineral-based products like bentonite sheet waterproofing and crystalline/capillary concrete waterproofing when they can be used. These products do not contain any chemicals likely to be a concern during the products’ use. While Crystalline/capillary concrete waterproofing does have significant life cycle concerns, it fares better than products that fall below it on the HBN’s product guidance ranking. Let’s discuss this further.
- Petroleum. Polymethyl methacrylate (PMMA) and polyurethane are all commonly used petroleum based waterproofing materials. Oil and gas extraction and processing can have significant impacts on surrounding communities, or “fenceline communities”.1 Oil and gas wells and refining facilities in the United States are disproportionately located in communities of color and low-income communities and contribute to environmental injustices.2 Polyurethane and PMMA are used in greater amounts and require more hazardous chemical inputs than the polyethylene and polypropylene films on bentonite sheet waterproofing. Thus, they can have greater impacts through chemical and product manufacturing.3
- Asphalt. Asphalt can expose installation teams to bitumen fumes, which are identified as an occupational carcinogen.4 Production of asphalt releases hazardous chemicals, such as polycyclic aromatic hydrocarbons, hydrogen sulfide, lead, and copper, into the environment. These releases expose fenceline communities to a wide array of chemicals that can impact their health.5 Asphalt is a petroleum-based material so we must also consider impacts we noted above which are burdening people living in fenceline communities further back in the supply chain.
- Cement. Crystalline/capillary waterproofing contains a large quantity of Portland cement. The most common method of producing Portland cement involves heating limestone in cement kilns to extremely high temperatures to produce clinker, the primary component of cement. These cement kilns are typically powered by burning fossil fuels like coal. The process emits hazardous chemicals, such as lead, mercury, and benzene, that impact fenceline communities.6
- Application Method. Many types of waterproofing and dampproofing require or suggest some type of personal protective equipment (PPE). PPE is recommended for crystalline/capillary waterproofing to protect installation teams from respiratory or skin-sensitizing dust generated when products are mixed. Products that react on site, such as cold fluid-applied PMMA waterproofing and polyurethane waterproofing, are of particular concern because they contain highly reactive chemicals that are respiratory sensitizers. Isocyanates, in particular, have been identified as a leading cause of work-related asthma.7 These products also contain catalysts that are developmental and reproductive toxicants. All asphalt products contain known carcinogens (cancer causing) polycyclic aromatic hydrocarbons (PAHs), and products that are heated on site are of even greater concern because of the additional asphalt fumes that are released.8 Occupational exposure to asphalt fumes during roofing, which uses similar hot-applied asphalt waterproofing, has been identified to be ‘probably carcinogenic to humans’ by the International Agency for Research on Cancer (IARC).9
The recommendations below can guide your conversations around what type of waterproofing is appropriate for your project:
- Prefer bentonite sheet waterproofing for applications where appropriate.
- Prefer crystalline waterproofing for concrete substrates if bentonite sheet waterproofing cannot be used.
- Prefer cold-applied asphalt emulsions over solvent-based products, foundation waterproofing sheet membranes, and hot-applied asphalt waterproofing if asphalt-based products must be used.
- Avoid products reacted on-site, like PMMA and polyurethane waterproofing.
When we think about material health it is easy to stop at the chemicals that building occupants may be exposed to. HBN’s Product Guidance demonstrates that a broader approach to material health considerations can be used to determine how the materials we choose impact public health and the environment. For some applications it may not be possible to use the preferred products, so remember that any movement up the HBN’s product ranking is a move in the right direction.
 “Environmental Impacts of Natural Gas,” Union of Concerned Scientists, June 19, 2014, https://www.ucsusa.org/resources/environmental-impacts-natural-gas; Tim Donaghy and Charlie Jiang, “Fossil Fuel Racism: How Phasing Out Oil, Gas, and Coal Can Protect Communities,” April 13, 2021, https://www.greenpeace.org/usa/reports/fossil-fuel-racism/.
 Gonzalez, David J. X., Anthony Nardone, Andrew V. Nguyen, Rachel Morello-Frosch, and Joan A. Casey. “Historic Redlining and the Siting of Oil and Gas Wells in the United States.” Journal of Exposure Science & Environmental Epidemiology, April 13, 2022, 1–8. https://doi.org/10.1038/s41370-022-00434-9.; Tim Donaghy and Charlie Jiang, “Fossil Fuel Racism: How Phasing Out Oil, Gas, and Coal Can Protect Communities,” April 13, 2021, https://www.greenpeace.org/usa/reports/fossil-fuel-racism/.
 Ann Blake and Mark Rossi. “Plastics Scorecard.” Clean Production Action, July 1, 2014. https://www.cleanproduction.org/resources/entry/plastics-scorecard-resource.
 International Agency for Research on Cancer (IARC). “Occupational Exposures to Bitumens and Their Emissions,” 2011. https://www.iarc.who.int/wp-content/uploads/2018/07/IARC_Bitumen_Eng-1.pdf; International Agency for Research on Cancer (IARC). Bitumens and Bitumen Emissions, and Some N- and S-Heterocyclic Polycyclic Aromatic Hydrocarbons. Vol. 103. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. https://publications.iarc.fr/Book-And-Report-Series/Iarc-Monographs-On-The-Identification-Of-Carcinogenic-Hazards-To-Humans/Bitumens-And-Bitumen-Emissions-And-Some-Em-N-Em---And-Em-S-Em--Heterocyclic-Polycyclic-Aromatic-Hydrocarbons-2013; National Institute for Occupational Safety and Health (NIOSH). “Hazard Review: Health Effects of Occupational Exposure to Asphalt.,” December 2000. doi.org/10.26616/NIOSHPUB2001110
 Based on U.S. EPA Toxics Release Inventory Data from 2020; Also see U.S. EPA. “Residual Risk Assessment for the Asphalt Processing and Asphalt Roofing Manufacturing Source Categories in Support of the 2019 Risk and Technology Review Final Rule,” December 2019. https://downloads.regulations.gov/EPA-HQ-OAR-2017-0662-0038/content.pdf.
 Veena Singla and Sasha Stashwick. “Cut Carbon and Toxic Pollution, Make Cement Clean and Green.” NRDC (blog), January 18, 2022. https://www.nrdc.org/experts/sasha-stashwick/cut-carbon-and-toxic-pollution-make-cement-clean-and-green.
 US Occupational Safety and Health Administration. “OSHA Fact Sheet: Do You Have Work-Related Asthma? A Guide for You and Your Doctor,” March 2014. https://www.osha.gov/Publications/OSHA3707.pdf.; Rosenman, Kenneth D., Mary Jo Reilly, and Barton G. Pickelman. “2019 Annual Report Tracking Work-Related Asthma in Michigan.” Michigan State University, July 20, 2020. https://oem.msu.edu/images/annual_reports/2019-WRA-Annual-Report-FINAL.pdf.; Lefkowitz, Daniel, Elise Pechter, Kathleen Fitzsimmons, Margaret Lumia, Alicia C. Stephens, Letitia Davis, Jennifer Flattery, et al. “Isocyanates and Work-Related Asthma: Findings from California, Massachusetts, Michigan and New Jersey, 1993-2008.” American Journal of Industrial Medicine 58, no. 11 (November 2015): 1138–49. https://doi.org/10.1002/ajim.22527.; US Environmental Protection Agency. “Methylene Diphenyl Diisocyanate (MDI) and Related Compounds Action Plan [RIN 2070-ZA15],” April 2011. https://www.epa.gov/sites/production/files/2015-09/documents
 National Institute for Occupational Safety and Health (NIOSH). “Hazard Review: Health Effects of Occupational Exposure to Asphalt.,” December 2000. doi.org/10.26616/NIOSHPUB2001110.
 International Agency for Research on Cancer (IARC). “Occupational Exposures to Bitumens and Their Emissions,” 2011. https://www.iarc.who.int/wp-content/uploads/2018/07/IARC_Bitumen_Eng-1.pdf; International Agency for Research on Cancer (IARC). Bitumens and Bitumen Emissions, and Some N- and S-Heterocyclic Polycyclic Aromatic Hydrocarbons. Vol. 103. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. Accessed January 25, 2022. https://publications.iarc.fr/Book-And-Report-Series/Iarc-Monographs-On-The-Identification-Of-Carcinogenic-Hazards-To-Humans/Bitumens-And-Bitumen-Emissions-And-Some-Em-N-Em---And-Em-S-Em--Heterocyclic-Polycyclic-Aromatic-Hydrocarbons-2013