Firestopping & Fireblocking Product Guidance

Use the red-to-green product guidance below to select safer product types by avoiding those in red and preferring yellow and green, which are safer for occupants, fenceline communities, and workers.

When choosing firestopping systems:

  • Prefer assemblies that allow for the use of mineral-based caulks, mortars, and pillows.
  • Prefer products, like firestop pillows, that do not need to be replaced when accessing through penetrations.
  • Where joint sealants are necessary, prefer acrylic products over silicones and polyurethanes.

Firestopping products are designed to prevent the passage of water, smoke, flames, and hot gasses through building penetrations in fire-rated assemblies in the event of a fire, for instance those around pipes, electrical and data cables, and outlets. Fireblocking products are used on non-fire-rated assemblies and are designed to contain the fire within concealed cavities.[1] A variety of materials are used in firestopping and fireblocking. This guidance focuses on sealants, mortars, and intumescent products installed in penetrations and other openings in floors, walls, and partitions. 

Firestopping and fireblocking products can contain hazardous chemicals such as halogenated flame retardants, orthophthalate plasticizers, organotin catalysts, and isocyanates. Similar to many other types of building products, firestopping and fireblocking products can be produced using hazardous processes that expose workers and nearby communities to substances that can impact their health. For instance, many firestopping products are made with a high percentage of petrochemicals, which are derived from oil and natural gas. Living in close proximity to oil and gas wells has been associated with numerous health impacts, including adverse pregnancy outcomes, cancer, exacerbation of asthma, and mental health issues.[2] A recent body of research also demonstrates that oil and gas wells are disproportionately located near historically redlined communities composed of high percentages of people of color, contributing to environmental injustice.[3]

Because firestopping products and systems are often not interchangeable, this guidance is intended to guide collaboration and discussion among stakeholders around material health considerations early on in the design process. This guidance aims to help you minimize the use of products that introduce hazardous chemicals into the environment and that can impact human health. It should be considered in tandem with all applicable safety requirements and applicable building codes.

Here is more detailed guidance to use when choosing firestopping and fireblocking materials:

  • Prefer assemblies that allow for the use of mineral-based caulks, mortars, and pillows. These materials typically contain less hazardous content and are composed of fewer petrochemicals than other types of firestopping products.
  • Prefer products, like firestop pillows, that do not need to be replaced when accessing through penetrations. This can reduce the chemical impacts associated with production by preventing the need for new products.
  • Where joint sealants are necessary, prefer acrylic products over silicones and polyurethanes. Acrylic sealants tend to contain fewer hazardous chemicals than other types of sealants.

Non-combustible sodium silicate caulks are composed of minerals and cure via water evaporation. They contain a sodium silicate intumescent that provides fireblocking properties. 

These products are relatively low hazard. They are made primarily of minerals with limited petrochemical content. They contain a small amount of crystalline silica, which is a carcinogen when respirable. Workers may be exposed when dust is generated during extraction and processing of minerals containing quartz, or during product manufacturing.

Firestop pillows or cushions are usually comprised of an insulating, heat-resistant core surrounded by an intumescent material and sealed in a plastic bag. The core is commonly made of mineral wool with a urea formaldehyde binder. These binders can release formaldehyde, a carcinogen and respiratory sensitizer, over time. The remaining content is relatively low hazard, although there are some hazardous chemicals used to manufacture the fiberglass and intumescent system. One advantage of these products is that they can easily be moved, reducing the total amount of product used over time in areas that require frequent access or retrofitting.

Within this type watch out for: Products that use bags coated with PVC.[4] More hazardous chemicals are required to make PVC than other types of plastic used in firestop pillow bags, such as polyethylene.[5] PVC production may have greater impacts on workers and fenceline communities relative to those plastics. PVC also has additional end-of-life concerns relative to other plastics, including its potential to form persistent, bioaccumulative toxicant dioxins when burned.[6]

Firestop mortars are used to seal through penetrations, construction gaps, and other openings in concrete or masonry assemblies. Some contain viscosity modifiers that can be carcinogenic in dust form, a consideration since these products are powders mixed with water on-site. Fuel- and process-related emissions from Portland cement manufacture can expose fenceline communities to toxic chemicals, including mercury. 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.[7]

Firestop putties are made of mineral filler, a binder, and an intumescent designed to expand during a fire. They may be used to protect various construction openings and are frequently used in openings created by electrical boxes. These products commonly contain chemicals that have few known hazards during use, but information on their contents’ potential toxicity is limited. 

Hazardous chemicals, such as the carcinogens formaldehyde and acetaldehyde, are used to produce the common intumescent system used in these products. In addition, over half of the product is composed of petrochemicals. Oil and gas extraction and refining, necessary for the production of petrochemicals, exposes fenceline communities to elevated concentrations of hazardous pollution.[2, 3]

Firestop putties commonly contain a large amount of polymeric binder. These polymers are not always disclosed, but one common binder system is styrene-butadiene rubber (SBR). SBR is produced using styrene and butadiene, which are both carcinogens.

Within this type watch out for: Products containing formaldehyde-based char-forming resins or silicones. During products’ use, formaldehyde-based resins can release a small amount of residual formaldehyde, a carcinogen. These are usually listed in safety data sheets (e.g. “phenol formaldehyde polymer”). Hazardous chemicals are integral to the production of both SBR and silicones. Still, the latter are a priority for avoidance since they are made from or form cyclic siloxanes during manufacturing, which are persistent and bioaccumulative toxicants. Technical or product data sheets may indicate whether or not silicones are present.

Acrylic firestop sealants and joint sprays are water-based products that contain acrylic polymers, and are similar in composition to standard acrylic sealants. They are non-reactive and cure via water evaporation. Most of the contents in these products are not expected to be hazardous during the products’ use. However, acrylic polymers are produced using hazardous chemicals such as the carcinogens ethyl acrylate and acrylonitrile. Acrylic firestop sealants and joint sprays are also comprised of roughly one third petrochemicals by weight. Oil and gas extraction and refining, necessary for the production of petrochemicals, exposes fenceline communities to elevated concentrations of hazardous pollution.[2, 3]

Within this type watch out for: Products containing orthophthalate plasticizers. Orthophthalates, also known as phthalates, are a class of chemicals that should be avoided because they are developmental toxicants and endocrine disruptors that can mimic hormones and are associated with numerous health effects.[8]

Acrylic intumescent firestop sealants are similar to standard acrylic firestop sealants, but they contain an intumescent system that expands during a fire to prevent the passage of smoke and flames. The intumescent is commonly based on expandable graphite and is produced using the hazardous chemicals sulfuric acid, a carcinogen, and potassium permanganate, a developmental toxicant

While these products are water-based, petrochemicals still account for more than a third of the product by weight. Oil and gas extraction and refining, necessary for the production of petrochemicals, exposes fenceline communities to elevated concentrations of hazardous pollution.[2, 3]

Within this type watch out for: Products containing orthophthalate plasticizers. Orthophthalates, also known as phthalates, are a class of chemicals that should be avoided because they are developmental toxicants and endocrine disruptors that can mimic hormones and are associated with numerous health effects.[8]

Silicone firestop sealants can be applied as caulks or spray-applied. These products commonly contain organotin catalysts that can be reproductive and developmental toxicants. Silicone sealants cure by reacting with moisture in the air. This reaction releases chemicals that vary depending on the particular product. The most common systems used in firestopping products release 2-butanone oxime, a carcinogen.

Silicones themselves are produced with a number of hazardous chemicals that include methyl chloride, a carcinogen, and developmental and reproductive toxicant. Cyclic siloxanes are integral to the production of silicones, used as an input or formed during manufacturing, and are persistent and bioaccumulative toxicants. Silicone firestop sealants and joint sprays contain the most petrochemicals per unit volume of all products reviewed. Oil and gas extraction and refining, necessary for the production of petrochemicals, exposes fenceline communities to elevated concentrations of hazardous pollution.[2, 3]

Within this product type prefer: Products that use titanium-based catalysts to avoid organotins. Silicone products that avoid organotins are still not a recommended product type, so prefer options ranked green or yellow.

One-part polyurethane foams used for fireblocking or firestopping contain several hazardous chemicals. The uncured products contain large amounts of isocyanates, which are respiratory sensitizers. They also commonly contain the halogenated flame retardant tri-(2-chloroisopropyl)phosphate (TCPP) and can contain additional halogenated flame retardants such as chlorinated paraffins and brominated polyols. Halogenated flame retardants are a class of chemicals that are a high priority for avoidance because they can be persistent and toxic.[9]

One-part polyurethane products also commonly contain organotin catalysts that can be reproductive and developmental toxicants. In addition, they contain blowing agents that cause them to foam. The most common blowing agent is a mixture that includes isobutane, a suspected carcinogen and mutagen. While less common, some products use hydrofluorocarbons (HFCs) with high global warming potential. 

Polyurethanes are composed almost entirely of petrochemicals. Oil and gas extraction and refining, necessary for the production of petrochemicals, exposes fenceline communities to elevated concentrations of hazardous pollution.[2, 3]

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] International Code Council. “2018 International Residential Code (IRC) - CHAPTER 3 BUILDING PLANNING - R302.4.1.2 Penetration Firestop System.” Accessed November 27, 2023. https://codes.iccsafe.org/s/IRC2018/chapter-3-building-planning/IRC2018-Pt03-Ch03-SecR302.4.1.2; Construction Specifications Institute. “MasterFormat® - Construction Specifications Institute.” Accessed November 27, 2023. https://www.csiresources.org/standards/masterformat.; International Code Council. “2018 International Residential Code (IRC) - CHAPTER 3 BUILDING PLANNING - R302.11 Fireblocking.” Accessed November 27, 2023. https://codes.iccsafe.org/s/IRC2018P7/part-iii-building-planning-and-construction/IRC2018P7-Pt03-Ch03-SecR302.11#.

[2] “Environmental Impacts of Natural Gas,” Union of Concerned Scientists, June 19, 2014, https://www.ucsusa.org/resources/environmental-impacts-natural-gas; Garcia-Gonzales, Diane A., Seth B.C. Shonkoff, Jake Hays, and Michael Jerrett. “Hazardous Air Pollutants Associated with Upstream Oil and Natural Gas Development: A Critical Synthesis of Current Peer-Reviewed Literature.” Annual Review of Public Health 40, no. 1 (2019): 283–304. https://doi.org/10.1146/annurev-publhealth-040218-043715; Deziel, Nicole C. “Environmental Injustice and Cumulative Environmental Burdens in Neighborhoods Near Oil and Gas Development: Los Angeles County, California, and Beyond.” American Journal of Public Health 113, no. 11 (November 2023): 1173–75. https://doi.org/10.2105/AJPH.2023.307422; Deziel, Nicole C., Cassandra J. Clark, Joan A. Casey, Michelle L. Bell, Desiree L. Plata, and James E. Saiers. “Assessing Exposure to Unconventional Oil and Gas Development: Strengths, Challenges, and Implications for Epidemiologic Research.” Current Environmental Health Reports 9, no. 3 (September 1, 2022): 436–50. https://doi.org/10.1007/s40572-022-00358-4.

[3] 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; Berberian, Alique G., Jenny Rempel, Nicholas Depsky, Komal Bangia, Sophia Wang, and Lara J. Cushing. “Race, Racism, and Drinking Water Contamination Risk From Oil and Gas Wells in Los Angeles County, 2020.” American Journal of Public Health 113, no. 11 (November 2023): 1191–1200. https://doi.org/10.2105/AJPH.2023.307374; Chan, Marissa, Bhavna Shamasunder, and Jill E. Johnston. “Social and Environmental Stressors of Urban Oil and Gas Facilities in Los Angeles County, California, 2020.” American Journal of Public Health 113, no. 11 (November 2023): 1182–90. https://doi.org/10.2105/AJPH.2023.307360; 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/.

[4] “Intumescent Pillows FiP - Fischer International.” Accessed December 15, 2023. https://www.fischer-international.com/en/products/firestop/intumescent-pillows-fip.

[5] Ann Blake and Mark Rossi. “Plastics Scorecard.” Clean Production Action, July 1, 2014. https://www.cleanproduction.org/resources/entry/plastics-scorecard-resource.

[6] Zhang, Mengmei, Alfons Buekens, Xuguang Jiang, and Xiaodong Li. “Dioxins and Polyvinylchloride in Combustion and Fires.” Waste Management & Research 33, no. 7 (July 1, 2015): 630–43. https://doi.org/10.1177/0734242X15590651; Avakian Maureen D, Dellinger Barry, Fiedler Heidelore, Gullet Brian, Koshland Catherine, Marklund Stellan, Oberdörster Günter, et al. “The Origin, Fate, and Health Effects of Combustion by-Products: A Research Framework.” Environmental Health Perspectives 110, no. 11 (November 1, 2002): 1155–62. https://doi.org/10.1289/ehp.021101155.

[7] 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

[8] Gore, A. C., V. A. Chappell, S. E. Fenton, J. A. Flaws, A. Nadal, G. S. Prins, J. Toppari, and R. T. Zoeller. “EDC-2: The Endocrine Society’s Second Scientific Statement on Endocrine-Disrupting Chemicals.” Endocrine Reviews 36, no. 6 (December 2015): E1–150. https://doi.org/10.1210/er.2015-1010; Engel, Stephanie M., Heather B. Patisaul, Charlotte Brody, Russ Hauser, Ami R. Zota, Deborah H. Bennet, Maureen Swanson, and Robin M. Whyatt. “Neurotoxicity of Ortho-Phthalates: Recommendations for Critical Policy Reforms to Protect Brain Development in Children.” American Journal of Public Health, February 18, 2021, e1–9. https://doi.org/10.2105/AJPH.2020.306014; Bennett Deborah, Bellinger David C., Birnbaum Linda S., Bradman Asa, Chen Aimin, Cory-Slechta Deborah A., Engel Stephanie M., et al. “Project TENDR: Targeting Environmental Neuro-Developmental Risks The TENDR Consensus Statement.” Environmental Health Perspectives 124, no. 7 (July 1, 2016): A118–22. https://doi.org/10.1289/EHP358; American Public Health Association. “A Precautionary Approach to Reducing American Exposure to Endocrine Disrupting Chemicals,” November 9, 2010. https://apha.org/Policies-and-Advocacy/Public-Health-Policy-Statements/Policy-Database/2014/07/09/09/03/A-Precautionary-Approach-to-Reducing-American-Exposure-to-Endocrine-Disrupting-Chemicals.

[9] DiGangi, Joseph, Arlene Blum, Åke Bergman, Cynthia A. de Wit, Donald Lucas, David Mortimer, Arnold Schecter, Martin Scheringer, Susan D. Shaw, and Thomas F. Webster. “San Antonio Statement on Brominated and Chlorinated Flame Retardants.” Environmental Health Perspectives 118, no. 12 (October 28, 2010): A516–18. https://doi.org/10.1289/ehp.1003089.

 

Last updated: December 15, 2023