Probabilistic assessment of the impact of material properties on the risk of frost damage in masonry constructions

Historically valuable buildings often contain a huge energy saving potential due to their current lacking thermal performance of the building envelope. Next to this, unfortunately insulation measures, which normally occur at the inside, induce a decrease in the temperature and drying potential of the structure which results in a risk for frost damage. To validate this risk Heat, Air and Moisture simulations are a valuable tool. Heritage facades often consist of masonries, which are known to have a complex hygrothermal behaviour. Therefore nowadays a homogenization of the masonry, for example to a homogenous brick wall, is often assumed to save computational time. Nevertheless these homogenizations, which include neglecting mortars, can have a drastic impact on the hygrothermal behaviour of masonries. Hence this study compares the impact of basic material parameters for the brick, pointing mortar and bed mortar of a masonry separately under a constant indoor and outdoor climate based on probabilistic simulations. The evaluation is done for three frost related criteria. Generally, the main impact parameters for the one and a half brick construction are found to be quite similar for interior insulated and not insulated cases but diverse between the chosen criteria