Risk analysis of biodeterioration of wooden beams embedded in internally insulated masonry walls

Energy retrofit of the envelope of existing historical buildings, due to their historical and cultural value, often includes the addition of an interior insulation layer. The new wall configuration changes the hygrothermal performance of the structure leading to higher moisture contents that increase the risk of damage, especially in wooden components. The hygrothermal performance of different retrofitted masonry assemblies is studied through HAM (Heat Air and Moisture) numerical simulations, for different external renders. Simulation results are post-processed using a damage model for wooden materials to evaluate the risk of biological deterioration as a consequence of the addition of an interior insulation layer. The external render, and in particular the combination of its liquid and vapor transport properties, strongly influences the hygrothermal behavior of the wall and, thus, the risk of moisture related damage to embedded wooden structures as a consequence of addition of interior insulation.