Wall base ventilation system to treat rising damp: The influence of the size of the channels

One of the major causes of pathologies in our historic buildings is the presence of moisture, particularly rising damp. Since these constructions tended to be built near water lines, to facilitate their supply, and because their walls are mainly made of high porosity materials, the presence of rising damp is constant. Although many historic buildings in Portugal have already been the targets of interventions to eliminate pathologies, the fact is that it has not been possible to do it properly. The treatment techniques available nowadays are quite diverse but all of them have low applicability to historic constructions. Research has been carried out, in this past years, at the Department of Civil Engineering of the University of Coimbra in collaboration with Department of Civil Engineering of the Faculty of Engineering of the University of Porto to try and solve this problem. An old but poorly studied technique has been investigated experimentally and numerically in the past few years: ventilation of the base of the walls. It was experimentally validated to limestone walls 20 cm thick. Numerical investigation has been carried out in order to analyze the influence of different parameters on its efficiency. In this paper we present the results of the latest investigations that have been carried out about the influence of the size of the ventilation channel on its efficiency.