Experimental study on hygrothermal behaviour of retrofit solutions applied to old building walls

Rural houses are usually built with traditional materials, stone and wood, and have a poor thermal and hygrometric behaviour. On the other hand, this kind of residences are generally degraded, and it is necessary to study adequate solutions to rehabilitate roofing (wood structures), walls (stone masonry) and floors (wood), particularly to improve house envelop resistance to water penetration and thermal comfort. Is it also urgent, as well, to study and develop adequate methodologies for the rehabilitation of such typical construction having this specific characteristics. Thus, under this scope, an experimental study on hygrothermal behaviour of retrofit solutions applied to old building stone masonry walls is presented. This analysis has been carried out in order to evaluate the influence of some wall retrofit solutions that can increase its thermal resistance. The study took place in laboratory, using a climate chamber, in which variations of temperature and humidity that occur in a stone masonry wall have been measured. The results obtained in laboratory were compared with analytical results obtained using specific software for the assessment of probability of occurrence of walls internal condensation. The experimental results obtained in this work contribute to a better understanding of the thermal-hygrometric behaviour of stone masonry walls, when thermal rehabilitation solutions are applied to its inside surface. The study also points out the importance of using repair-building solutions that can minimize the risk of superficial and internal condensation.