Moisture detection in wood and plaster by IR thermography

In the last decade, many research have been carried on the application of IRT to detect moisture in the materials of historic buildings, but only few studies are comprehensive of IRT application on wood. The thermal characteristics of timber are highly different from the porous materials ones; particularly, the thermal capacity of wood is lower than bricks, stone and mortar. Laboratory researches and scientific literature determined that the water content detection in porous materials is more related the evaporation rate of the surfaces and the presence of soluble salts than to the absorption capability of the materials. Moreover a correlation between moisture content, evaporation and boundary conditions was studied by analyzing evaporation fluxes at different environmental conditions and water content. Because of the lower heat capacity of the timber, the thermographic shot after the heating can be affected by the influence of water presence. Lab tests and study cases show the advantages and the limit of the IRT techniques, and the results obtained permit the comparison between the different heating systems applied. (C) 2004 Elsevier B.V. All rights reserved.