The damp-proof course (DPC) is an important system within our house’s structure to ensure that dampness does not build up within the house. However, in the earlier days, the materials used to build the DPC like roofing slates, lead sheets, glazed ceramic tiles, and bitumen-based materials, were not as effective as the present day’s black polyethylene sheeting. As this is so, a lot of the walls of these older houses had to pay the price, where rising damps, a condition when ground water rises through the walls, would occur. This made these houses look unsightly where the problem occurred. Thus, damp treatment for walls is required.
In this situation, the best and most effective solution to overcome such problems is to insert a new DPC in the base of the walls. The new DPC can be installed either physically or chemically. The traditional method of undersetting requires progressive replacement as the base is removed and the DPC and new materials are inserted. For places with dampness caused by high salt concentrations, this is the best method used since the salted masonry is removed and replaced. Another way is to saw a slot of the wall horizontally along the mortar joints, and the DPC membrane is inserted while refilling the joints. The chemical method, on the other hand, is done by injecting water-repelling substances into the wall where holes are drilled for the purpose. Especially if the base is thick, this is difficult to be done properly.
Other methods like getting ventilation and site drainage is also effective. However, these require much maintenance, as compared to the DPC which you will just require regular inspection to ensure it works properly. Overall, the best damp treatment for walls when it is due to a defective DPC is to get a new DPC installed altogether.