Thermal conductivity is a measure of the rate of heat flow through one unit thickness of a material subjected to a temperature gradient. The thermal conductivity of common structural woods is much less than the conductivity of metals with which wood often is mated in construction. It is about two to four times that of common insulating material. For example, the conductivity of structural softwood lumber at 12% moisture content is in the range of 0.7 to 1.0 Btu×in/(h×ft²×^oF) compared with 1,500 for aluminum, 310 for steel, 6 for concrete, 7 for glass, 5 for plaster, and 0.25 for mineral wool.

In Chapter 4 of the USDA Forest Products Lab Wood Handbook, Table 4-7, entitled “Thermal conductivity of selected hardwoods and softwoods” lists thermal properties for various species of wood.