Degradation Control of Historical Walls with Rising Damp Problems

Abstract

Treating rising damp in the walls of historical buildings is a very complex procedure. Moisture transfer in the walls of old buildings in direct contact with the ground leads to the migration of soluble salts, which are responsible for many building pathologies. This work follows two main lines of research: one theoretical (analytical and numerical) and one experimental. The theoretical part describes an extensive analysis of the phenomenon of rising damp using an analytical equation based on the concepts and methods of unsaturated flow theory, and a numerical validation study. The results show that the simple analytical model clearly describes the rising damp front when compared with the numerical simulations. The influence of wall thickness, boundary conditions, wall composition and material properties such as porosity and sorptivity are analyzed in detail. The experimental part presents the results of the work developed by the Building Physics Laboratory (LFC) to treat rising damp in a historical church, locate in Northern Portugal. The main purpose is to validate the technology of wall base ventilation, for treating rising damp in walls of historic buildings. The analytical model used and the numerical results obtained describe well the observed features of rising damp in walls, verified by in-field tests, who contributed for a simple sizing of the HUMIVENT device to be implement in historic buildings.