ThermoWood® Construction ThermoWood® is a special thermally modified timber developed in Finland. The timber is heated treated up to 215 °C to remove all excess moisture. This wood is well suited for outdoor applications where demanding weather conditions are the norm. The key performance features of ThermoWood® over normal timber are: Improved durability against decay Resin removed Improved dimensional stability Consistent colouring throughout Reduced equilibrium moisture content