Urea formaldehyde foam (UFF) possesses outstanding properties of fire resistance, low smoke emission, low toxicity, and excellent insulation. These properties make it suitable for thermal insulation in buildings. UFFs were prepared in this work via a foaming technology using hexane as a physical-blowing agent. By the use of varying dosages of hexane, the effect of hexane on the properties of UFF was investigated. Increased hexane dosage was shown to cause an adverse effect on the properties including compression strength, pulverization rate and limiting oxygen index. Foam microstructure was analyzed through scanning electron microscopy (SEM); cell sizes were determined and the mean cell size increased with increasing hexane dosage. This work further investigated the relationship between the physical properties and density of UFF. Furthermore, the pyrolysis behaviour of UFF and the corresponding evolution of gaseous products were examined by using a thermogravimetric analyzer coupled with Fourier transform infrared spectrometry (TG-FTIR). Gaseous products during the pyrolysis such as HNCO, NH₂CN, HCN, H₂O and CO₂ were found in the infrared spectra. And possible formation pathways for the main pyrolysis products were tentatively presented. The flammability of UFF was measured by cone calorimetry.