Nanocomposites have been increasingly used, as an alternative to traditional fire retardants, to improve the strength and fire retardancy of polymeric materials. A number of studies using the cone calorimeter showed that the nanoparticles used in small quantities (e.g., 3 wt%) reduce significantly the heat release rate (HRR). The formation of a surface layer on top of the unpyrolysed material is generally considered responsible for the reduced HRR. In a previous study, the global effects of the surface layer were examined by the present authors and a methodology was subsequently developed to predict pyrolysis of a polyamide nylon (PA6) nanocomposite in good agreement with the experimental data. This work presents further validation of the methodology for two more nanocomposites, namely polybutylene terephthalate and ethylene-vinyl acetate. Furthermore, the existing model is extended to explain the effects of change in the nanofiller loading on the HRR, and the modified model is applied to the experimental data obtained for a PA6 nanocomposite by Morgan et al. (Fire and polymers: materials and solutions for hazard prevention. American Chemical Society, Washington, DC, 2001, pp 9-23).