Foam insulation in its various forms – polyeurethane (typically sprayed) or polyisocyanurate and polystyrene (typically rigid) – has proven its ability to improve energy efficiency and occupant comfort. With consistent R-values per inch that exceed traditional insulations like fiberglass and cellulose, and the added benefit of better air barrier functionality, foams have become increasingly popular, especially in “green” buildings.
One factor that is often overlooked, however, is the flame retardant component in these insulators. Because foam is highly flammable, the building code currently requires the addition of chemicals that are suspected, and sometimes have been shown, to be toxic to human health and the environment. In a completed building, the foam is inert and non-toxic, so it is only during initial application, demolition or a fire event that the toxins could be released. Interestingly, a recent study suggests that flame retardants do little to improve fire safety, while the use of a thermal barrier such as drywall does make them fire safe – thus not requiring flame retardant.
When feasible, alternative insulations that perform well can be considered. Green Science Policy Institute has created a chart for your reference. On the regulatory side, the organization Safer Insulation Solutions is working to update U.S. building codes to enable the safe use of foam insulations without added flame retardants.