The article about residential fires attributed to spray polyurethane foam ( JLC Report, 10/11) states that I see the risk of fire from foam applications as minor. I hope readers understand that I do not imply that a fire that causes injury or death and major property damage is minor; only that the actual occurrence of fire attributed to spray-foam applications is extremely rare. I have extensively researched fires attributed to foam applications in order to develop fire safety documents, which were published by the American Plastics Council around 10 years ago. At that time, no fires were reported in houses, but a few were reported in commercial applications (caused by cutting or welding torches). I am aware of four fires linked to spray-foam applications over the last five years. To put this into perspective, conservative estimates indicate that there have been approximately 5,000 residential insulation contractors spraying foam during the last five years. If each of those contractors sprayed 25 houses a year, the total would be 625,000 jobs over that period. Assuming four fires have been linked to spray foam applications, that would be less than 1 in 100,000.

The article also reported that I said you would have to pile on a foot of foam or more for it to spontaneously combust. I think the word I used was "typically." Depending on chemical formulation, site conditions, and spray equipment settings, spontaneous combustion could occur in thinner or thicker applications.

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