In this work, we have studied the evolution of an flame retardant intumescent EVA-based material during combustion. The formulation uses an original concept of the laboratory, i.e., use of char forming polymer (here the polyamide-6) as carbonisation agent associated to a carbonisation catalyst in an intumescent formulation. The fire behavior was modelled using the cone calorimeter and we have explained the evolution of the rate of heat release curve in terms of chemistry of the system using FTIR and solid state NMR.