Photo Credit: Owens Corning Thermafiber


Rigid insulation is associated with several serious environmental and social impacts. The worst come from chemicals used during manufacturing: blowing agents with massive global warming potential and halogenated flame retardants. 1 Halogenated flame retardants like HBCD are substances of global concern; they are among the most toxic, persistent, and bio-accumulative substances used in building products. The EPA has also acknowledged its effects on the thyroid and potential reproductive toxicity. 2 Polystyrene insulation is the primary use of HBCD. The removal, recycling and disposal of this insulation from buildings will contribute to global HBCD pollution long after companies stop making the flame retardant. 1


Prioritize these products: 3


  • Mineral wool, cellular glass, cork, or wood fiber board insulation that have no blowing agents and require no flame retardants
  • Halogen-free polyisocyanurate insulation with Greenguard Gold or Indoor Advantage Gold certification
  • Low-global-warming-potential XPS (extruded polystyrene) with Cradle to Cradle Silver or higher

Finding it impossible to avoid XPS? Spec the product featured below or minimize its use by specifying it only where alternatives have a shorter history of use (such as under the slab) and use cleaner materials elsewhere. Alternatives such as mineral wool have more of a track record in low-slope roofs and rainscreen assemblies. 4