Waterproofing & Dampproofing Product Guidance

HBN’s Product Guidance identifies the biggest opportunities to select types of products that are safer for occupants, fenceline communities, and workers. Use the red-to-green ranking below to select safer product types by avoiding those in the red and preferring those in yellow and green.

Here is some general guidance to use when choosing waterproofing and dampproofing materials:

  • Prefer bentonite sheet waterproofing for applications where it is appropriate.
  • If bentonite sheet waterproofing cannot be used, prefer crystalline waterproofing for concrete substrates.
  • If asphalt-based products must be used, prefer cold-applied asphalt emulsions over solvent-based products, foundation waterproofing sheet membranes, and hot-applied asphalt waterproofing.
  • Avoid products reacted on-site, like PMMA and polyurethane waterproofing.

Waterproofing and dampproofing products are designed to prevent the penetration of water through both horizontal and vertical surfaces. Waterproofing refers to products designed to prevent the passage of liquid moisture, while dampproofing refers to products designed to resist the flow of water vapor.[1] While there is variation in the applications for which the products in this ranking will be used, there is also considerable overlap. 

Many waterproofing and dampproofing materials are based on asphalt. Use of asphalt can expose installation teams to bitumen fumes, which are identified as an occupational carcinogen.[2] In addition, production of asphalt releases hazardous chemicals such as polycyclic aromatic hydrocarbons, hydrogen sulfide, lead, and copper into the environment exposing fenceline communities to a wide array of chemicals that can impact their health.[3]  Therefore, products requiring significantly more asphalt for a given surface area are ranked worse on the spectrum than products requiring less asphalt. Similarly, Portland cement production results in hazardous environmental emissions, such as lead, mercury, and benzene, that can impact fenceline communities.[4]

Petroleum-based chemicals, including asphalt, also have impacts on fenceline communities farther back in the supply chain. Oil and gas extraction and processing have significant impacts on surrounding communities.[5] In the United States, oil and gas wells and refining facilities are disproportionately located in communities of color and low-income communities, contributing to environmental injustices.[6]

Here is some general guidance to use when choosing waterproofing and dampproofing materials:

  • Prefer bentonite sheet waterproofing for applications where it is appropriate. These products do not contain chemicals expected to be a concern during their use. In addition, bentonite sheet waterproofing has the fewest hazardous chemicals associated with manufacture and installation of the materials considered.
  • If bentonite sheet waterproofing cannot be used, prefer crystalline waterproofing for concrete substrates. While there are hazardous emissions associated with Portland cement production, required for crystalline concrete waterproofing, there was no hazardous content identified in these products themselves.
  • If asphalt-based products must be used, prefer cold-applied asphalt emulsions over solvent-based products, foundation waterproofing sheet membranes, and hot-applied asphalt waterproofing. While these products still contain hazardous content, including asphalt, cold-applied asphalt emulsions are water-based so they avoid the use of hazardous solvents. They also generally use less asphalt than other asphalt-based waterproofing.
  • Avoid products reacted on-site, like PMMA and polyurethane waterproofing. These products contain respiratory sensitizers, and other hazardous chemicals including carcinogens and developmental and reproductive toxicants.

Bentonite sheet waterproofing membranes do not contain any chemicals likely to be a concern during the products’ use, but they are not free of chemical concerns.  Bentonite strip mining can expose miners to respirable bentonite dust, which contains significant levels of silica.[7] Respirable silica is identified by numerous authoritative bodies as a carcinogen. If dust is generated during installation, this can also be a concern. In addition, sealants used during installation can contain solvents that add additional hazards.[8] 

Similar to bentonite sheet waterproofing, crystalline silica waterproofing contains little content expected to be a concern during use. Dust generated on-site when the product is mixed with water can irritate the skin and eyes. Crystalline concrete waterproofing is ranked lower than bentonite sheet waterproofing because, similar to other concrete products, Portland cement is an integral component of these products. Fuel-related and process related emissions from Portland cement manufacture can expose fenceline communities to toxic chemicals, including mercury.[9] In addition, decarbonization efforts often promote incineration of plastic and solid waste at cement kilns that can release additional harmful pollutants including dioxins, benzene, lead and mercury.[10] 

In general, it is best to avoid asphalt-based products whenever possible. Particular chemicals of concern in asphalt are polycyclic aromatic hydrocarbons (PAHs), which are known carcinogens. Cold-applied asphalt emulsions generally use less asphalt than other asphalt-based products and typically do not contain solvents. They can, however, contain potassium dichromate, a hexavalent chromium compound, which is a known carcinogen and has many other associated health hazards. Some substrates also require asphalt primers to be used, which can introduce additional hazardous chemicals during installation. In addition, asphalt production releases hazardous chemicals including PAHs into the air, which can affect workers and people living in nearby communities.[11]

As noted above, chemicals of particular concern in asphalt are polycyclic aromatic hydrocarbons (PAHs), which are known carcinogens. Solvents used in solvent-based asphalt dampproofing products introduce additional hazards. Stoddard solvent, a carcinogen and mutagen, is commonly used. In addition, asphalt production releases PAHs into the air, which can affect workers and people living in nearby communities.[12]

Sheet waterproofing membranes are composed of a polymer film laminated to a rubberized asphalt adhesive. This adhesive makes up the majority of the product by weight. As noted above, chemicals of concern in asphalt are polycyclic aromatic hydrocarbons (PAHs), which are known carcinogens. In addition, asphalt production releases PAHs and other chemicals into the air, which can affect workers and people living in nearby communities.[13] These products are ranked lower than water-based asphalt dampproofing products because they can contain a larger amount of carcinogenic chemicals including process oils that are persistent, bioaccumulative, and toxic.They also require contact adhesives and primers that may add additional hazards. For instance, primers can contain ethylene glycol, a developmental toxicant. Some sealants used for edges and lapping may contain hazardous content such as orthophthalates and organotin catalysts. See the sealants product guidance page for guidance on selecting safer sealants.

Cold fluid-applied polymethyl methacrylate (PMMA) waterproofing systems are made of multiple components that are reacted on site to create a water-resistant barrier. Much of the product is made up of respiratory sensitizers, including methyl methacrylate and other acrylates. Catalysts can contain orthophthalate plasticizers that are known developmental and reproductive toxicants and endocrine disruptors. Primers can also contain carcinogenic solvents. 

PMMA waterproofing requires a larger quantity of petroleum-based chemicals than higher-ranked materials. Extraction and processing of petroleum has significant impacts on fenceline communities, which are disproportionately communities of color and low-income communities.[14]

Single-component polyurethane waterproofing is based on isocyanates, which are potent respiratory sensitizers. While the levels of unreacted isocyanates are lower than in two-component polyurethane products, there are a number of other notable hazardous chemicals present in single-component polyurethane waterproofing. These include a high percentage of hazardous solvents that are carcinogens, mutagens, and/or developmental toxicants, as well as organotin catalysts with reproductive and developmental hazards. Single-component polyurethane waterproofing can also contain a high percentage of chlorinated paraffins as plasticizers. Chlorinated paraffins are a high priority for avoidance because some have been identified as persistent, bioaccumulative, and/or toxic.[15] These products also require primers such as two-part epoxies and polyurethanes for some surfaces, and may use a polyurethane topcoat. All of these accessory products add additional hazards. Finally, polyurethane requires more hazardous chemical inputs than many other materials, which can have impacts through chemical and product manufacturing.

Similar to other asphalt waterproofing and dampproofing products, hot-applied asphalt waterproofing is composed mostly of asphalt. In this case, it is heated on-site before it is applied. The U.S. Centers for Disease Control notes that asphalt fumes contain known carcinogens.[16] Occupational exposure to bitumen and bitumen fumes during roofing, which uses similar hot-applied asphalt waterproofing, has also been identified to be ‘probably carcinogenic to humans’ by the International Agency for Research on Cancer (IARC).[17] These products can also contain carcinogenic petroleum distillates, and primers commonly contain solvents that are carcinogens and mutagens. 

Hot-applied asphalt waterproofing uses the largest amount of asphalt per square foot relative to other asphalt-based waterproofing products considered, so these products have the potential for greater impacts on workers and nearby communities through releases of chemicals such as PAHs during manufacturing.[18]

Supporting Information

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.

Common Product Records Sourced

Endnotes

[1] Henshell, Justin. The Manual of Below-Grade Waterproofing. 2nd ed. London: Routledge, 2016. https://doi.org/10.4324/9781315618753.

[2]  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;

[3] 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.

[4] 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.

[5] “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/.

[6] 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/.

[7] Adamis, Zoltan, Williams, Richard B & International Programme on Chemical Safety. (‎2005)‎. Bentonite, kaolin and selected clay minerals. World Health Organization. https://apps.who.int/iris/handle/10665/43102

[8] “CCW MiraCLAY Sealant Safety Data Sheet.” Carlisle Coatings and Waterproofing, Inc, March 23, 2016. https://www.carlisleccw.com/view.aspx?mode=media&contentID=2443.

[9] 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.

[10] 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.

[11] Based on U.S. EPA Toxics Release Inventory Data for releases of polycyclic aromatic compounds from asphalt plants in 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.

[12] Based on U.S. EPA Toxics Release Inventory Data for releases of polycyclic aromatic compounds from asphalt plants in 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.

[13] Based on U.S. EPA Toxics Release Inventory Data for releases of polycyclic aromatic compounds from asphalt plants in 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.

[14] 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/.

[15] Chemsec. “Chlorinated Paraffins (CPs).” Chemsec SIN list. Accessed May 20, 2022. https://sinsearch.chemsec.org/chemical/63449-39-8.

[16] National Institute for Occupational Safety and Health (NIOSH). “Hazard Review: Health Effects of Occupational Exposure to Asphalt.,” December 2000. doi.org/10.26616/NIOSHPUB2001110.

[17] 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; 

[18] Based on U.S. EPA Toxics Release Inventory Data for releases of polycyclic aromatic compounds from asphalt plants in 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.

Last updated: August 01, 2022