In recent years, there has been increasing interest in the development of wood–plastic composites (WPC) for use as building materials. Using wood as natural reinforcement in composite materials, instead of mineral reinforcements, has several advantages such as low density, low cost, and less abrasive finish. The natural reinforcements are also non-toxic and recyclable. The wide variety of WPCs makes it difficult to discuss the performance of these composites. In this research, the bubble inflation technique, introduced by Joye et al., is used to study the behaviour of biocomposite materials in cold temperatures. The results of experiments with high-density polyethylene and WPC membranes with 20, 30, 40, 50 and 60 wt% of wood fibre, under the combined effect of temperature and pressure are presented. The membranes are tested under the maximum pressure of 18 psi within the temperature range of -50C to +50°C with 25°C increments.