IRT techniques for the detection of timber moisture

The object of this research is to develop a procedure using IRT to detect critical levels of moisture content in wood. Passive and active approaches are compared to define the most reliable procedure to map the moisture diffusion and to evaluate the moisture content of the surfaces. Laboratory research reported in the scientific literature has determined that the water content in porous materials is more related to the evaporative speed of the surfaces and the presence of soluble salts than to their absorption capability. Moreover, evaporative fluxes were studied at different environmental conditions and water content in order to determine a correlation between moisture content, evaporation and boundary conditions. The thermal characteristics of timber are different those of porous materials such as brick and stone and mortar, particularly in that the thermal capacity of wood is lower. Nevertheless, because of the lower heat capacity of wood, the presence of water greatly affects the wood thermal capacity. Therefore, the active procedure guarantees the best results. Lab tests and a study case (Knight House, Kirtland OH) show the advantages and the limits of IRT techniques, and the results obtained demonstrate the sensitivity of the method in oak and pine wood species.