Healthier Insulation
Watch our Six Classes video above on Flame Retardants
Introduction
Problem: For improved energy efficiency, foam plastic building insulation (polystyrene, polyisocyanurate, and polyurethane) is increasingly used in “green” buildings.
To meet flammability standards, the manufacturers often add flame retardant chemicals that are either known to be toxic or lack adequate health and environmental information. These chemicals do not increase fire safety when used below-grade or behind thermal barriers. (Navigate to Research to learn more.)
We have been working with architects, builders, policymakers and fire safety experts to reduce the use of flame retardants in building materials when they do not improve fire safety.
Foam plastic building insulation is used:
- in wall and ceiling cavities, including attic insulation (spray foam or foam board)
- below-grade foundation (foam board)
- under concrete slabs (foam board)
Flame retardant chemicals in building insulation
HBCD–Hexabromocyclododecane
In recent decades, the brominated flame retardant HBCD was added to polystyrene insulation (EPS and XPS). It bioaccumulates in fat, becoming more concentrated as it moves up the food chain. Marine mammals have on average 100 times greater levels of HBCD in their bodies than small aquatic organisms.
HBCD is associated with adverse reproductive, developmental, and neurological health effects. This harmful flame retardant was banned from use by the Stockholm Convention, a global treaty adopted by over 180 countries in order to reduce the release of Persistent Organic Pollutants (POPs).
PolyFR – brominated styrene butadiene copolymer
As manufacturers phased out HBCD, they substituted PolyFR, a polymeric brominated flame retardant. Adequate data on PolyFR is not currently available; according to the EPA, it is very persistent in the environment. PolyFR also presents serious lifecycle concerns, as research shows it breaks down into smaller and likely more toxic molecules. Like other brominated flame retardants, it may produce potentially carcinogenic compounds during combustion.
TCPP – (Tris(1-chloro-2-propyl) phosphate)
The chlorinated flame retardant TCPP, is used in most polyurethane and polyisocyanurate insulation (spray foam insulation). Research shows TCPP can accumulate in the livers and kidneys of rats, may be neurotoxic, and may cause reproductive toxicity in female mice.
HBCD bioaccumulates up the foodchain. (Covaci, 2006)
HBCD and TCPP are global pollutants found in:
- the environment and animals
- soil, sediment, and sewage sludge
- indoor air and dust
- and breast milk
Facts: Flame retardant chemicals in building insulation
| Flame Retardant Name and ID# | Use in insulation | Chemical Class | Health and Environmental Concerns | Legal restrictions |
|---|---|---|---|---|
HBCD Hexabromo-cyclododecane CAS RN: | Expanded and extruded (EPS and XPS) foam board insulation | Brominated organohalogen flame retardant | Neurodevelopmental toxicity Strong potential to bioaccumulate Persistent in air and subject to long-range transport Very toxic to aquatic organisms | Banned by the European Union in 2015 Recommended for global elimination by the Stockholm Convention Phased out by Canada in 2016 |
TCPP Tris (1-chloro-2-propyl) phosphate CAS RN: | Polyurethane and polyisocyanurate insulation (foam spray and boards) | Chlorinated organophosphate flame retardant | Persistent in the environment Accumulates in livers and kidneys Potential carcinogen, endocrine disruptor, reproductive toxin, and neurotoxin Lack of data | European Union: Regulated in toys under Toy Safety Directive Under study at the U.S. Environmental Protection Agency and National Toxicology Program Listed on the California Safer Consumer Products Candidate List |
Poly FR Brominated styrene butadiene copolymer CAS RN: 1195978-93-8 | Expanded and extruded (EPS and XPS) foam board insulation | Brominated organohalogen flame retardant | Persistent in the environment Lack of data |
Legislation
In 2013, California passed Assembly Bill 127 (AB127), directing the State Fire Marshal to reexamine flammability standards for building insulation, and if appropriate, to propose changes to the building and fire codes allowing for certain applications of foam plastic building insulation without the addition of chemical flame retardants, while still maintaining overall building fire safety.
Research makes the case for updating building codes
Flammability study finds adding flame retardants to below-grade foam plastic insulation provides no added fire safety benefit
The California Office of the State Fire Marshal (OSFM) directed researchers at Oklahoma State University to study foam plastic building insulation installed below-grade with and without added flame retardants.
The study found that:
- Adding flame retardants to foam plastic insulation does not significantly change peak heat release rates.
- The time to ignition for foam plastic insulation without flame retardants is comparable to other combustible construction materials.
- When installed below grade, insulation without flame retardants has no risk of fire spread to the structure and will not endanger occupants or responders.
- California’s residential building codes can be safely updated to allow use of below-grade foam plastic insulation without added flame retardants.
Read the full report, published on the California Office of the State Fire Marshal’s website.
Peer-reviewed paper: A case for re-evaluating building codes
Our interdisciplinary peer-reviewed paper, Flame retardants in building insulation: a case for re-evaluating building codes, explores the history, fire safety, health and environmental issues of flame retardants in building insulation. After extensive review of fire science studies, we concluded that flame retardants in building insulation do not provide a fire safety benefit for many applications.
We found that:
- Since 1961, building codes have required foam plastic insulation materials to meet flame spread requirements as measured by the Steiner Tunnel test. (pictured)
- The Steiner Tunnel test does not accurately measure the flame spread of foam plastics.
- Flame retardants are added to foam plastic materials to pass the Steiner Tunnel test, but they do not provide fire safety benefits in many building applications.
- Fire safety for foam plastics is provided instead by code provisions requiring firestopping and thermal barriers.
Read the full study, published in Building Research & Information
Read more on our blog
Picture shows the Steiner Tunnel test, which does not accurately measure the flame spread of materials which melt and drip like foam plastics. Photo: Intertek Testing Services, Inc.
Code Change
For healthier and energy-efficient buildings, codes and standards need to be updated to reduce the use of harmful flame retardant chemicals while maintaining fire safety.
In 2018, the California Office of the State Fire Marshal (OSFM) submitted a proposal to allow below-grade polystyrene insulation without added chemical flame retardants.
To learn more about this proposal and below-grade polystyrene insulation without added flame retardants, please refer to either:
Resources
Science
- Peer-reviewed paper: Flame retardants in building insulation: a case for re-evaluating building codes
- USGBC-CA Council of Experts white paper on halogenated flame retardants in buildings
- Building Evidence for Health: a collection of fact sheets on key topics related to buildings and health created by the Harvard T.H. Chan School of Public Health.
Architects and Builders
- Flame retardant-free alternative insulations chart
