Wood is generally more insulating than rubber. This is due to wood's higher thermal conductivity compared to rubber. According to the U.S. Department of Energy, wood has a thermal conductivity of approximately 0.16 W/m·K, while rubber has a thermal conductivity of around 0.16-0.18 W/m·K. Despite the close values, wood's higher density and cellular structure contribute to its superior insulating properties. Wood's cellular structure contains air pockets, which act as natural insulators, reducing the heat transfer rate. Additionally, wood has a higher R-value, which is a measure of a material's resistance to heat flow. The R-value of wood ranges from 1.0 to 2.0 per inch, depending on the wood type and density, whereas rubber's R-value is typically lower. This indicates that wood is more effective at reducing heat transfer, making it a better insulator overall.