"Rigid polyurethane and polyisocyanurate spray-foams will, when ignited, burn rapidly and produce intense heat, and will act as fire accelerants. That leads them to sometimes being referred to as “solid gasoline”."
"In addition to being of such chemical composition that it acts as fire accelerant, a problem with foam spray-on insulation is the fact that it envelopes building structures in a continuous manner, making it prone to a quickly moving fire."
"To eliminate fire risk around foam insulation is not possible, so for the moment preventative measures are centred around creating a thermal barrier around the foam (such as GIB, cellulose, Portland cement etc) in an attempt to extend the time at which the foam would reach its auto ignition temperature should a fire originate from other sources."
I've been watching videos such as this: www.dailymotion.com/video/xquk2n_exclu-l-incendie-de-roubaix-filme-par-un-voisin_news#.UNtNW29X269
And reading articles such as this: foursevenfive.com/reason-foam-fails-2-unacceptable-fire-hazard/
It's, like... yeah.