California Building Standards Commission voted on 19th January 2019 to authorise the use of non-flame-retardant expanded polystyrene foam (EPS) insulation in specific circumstances buildings. This concerns only use in horizontal applications in foundations underneath 3.5 inch (8 cm) concrete. The InsulationValues website (Dow Dupont) indicates that this decision ignored the opinion of the Commission’s expert committee. The study commissioned to Oklahoma University to inform the proposed code change showed that non-FR EPS foam was much more easily ignited and flammable than FR EPS foam, but concluded that the non-FR foam was did not pose a higher risk than other flammable materials stored on building sites, and did not pose a significant fire risk as used in foundations, even if accidentally partially exposed. This report recommended that rulemaking to require flame retardancy of ABS piping be considered, because this was more flammable than the other construction materials tested (EPS foams, rolled polyethylene sheetings), and that all flame retardants should be evaluated for possible health and environmental impacts.
“Flammability Standards for Building Insulation Materials, Phase II Working Group Report: Final Report August 17, 2017”, https://osfm.fire.ca.gov/codedevelopment/pdf/CalFire-OSU_Phase_II_Working_Group_Final_Report.pdf and “Why Did the California Building Standards Commission Just Approve An Unregulated Building Product?”, 24 January 2019, InsulationValues (Dow Dupont) https://www.insulationvalues.com/accountability/2019/1/24/why-did-the-california-building-standards-commission-just-approve-an-unregulated-building-product