The fire behavior of various large samples polymers assemblies is an under‐researched topic. In fire risk assessment, the resultant heat release rate of burning different combustibles has to be known. To highlight interactions between components, 2 types of configurations were tested: juxtaposed and layered materials, using a specific radiant panel setup. For juxtaposed assemblies, results indicated that the more flammable component acted as an accelerator for the global combustion kinetics. For layered assemblies, 2 main phenomena were evidenced: the front material acted as a shield delaying the combustion of the backside material and the presence of a backside material induced a thermal thickening that slowed down the combustion of the front material. The experimental burning behaviors of the assembly were compared with a simulated one calculated from the superposition principle. This method was described by introducing a time offset and/or a slowdown factor in the model, confirmed with the use of different assemblies.