Building polymers are highly flammable and produce a vast amount of toxic chemical compounds in the event of a fire which can lead to potential incapacitation and death. To gain an in-depth understanding of this issue, smoke toxicity and thermal characteristics of seven commonly used building polymers were analysed through a systematic fire performance evaluation system using a Thermogravimetric Analyzer and a Cone Calorimeter coupled with an FTIR arrangement. Four Fractional Effective Dose (FED) expressions were compared to assess the smoke toxicity of the fire effluents based on different assumptions. It was found that FEDN2, calculated using Purser’s equation, reported the highest values of FED with the following order of potential smoke toxicity at 50 kW/m2 radiative heat flux: LDPU > HDPU > PE > HDEPS > XPS > EVA > LDEPS. Furthermore, fire performance evaluation of the polymers was carried out by considering three key fire risk parameters, i.e., flashover propensity, total heat released, and toxic hazard. At 50 kW/m2 radiative heat flux, HDPU exhibited 11.7 times flashover propensity compared to the least flammable polymer (HDEPS), EVA exhibited 5 times total heat release compared to the polymer with the lowest total heat release (LDEPS) and, LDPU exhibited 6.7 potential times toxic hazard compared to the least toxic polymer (EVA).