To prevent this from happening, we ensure that the damp proof spray stays intact on the wall by applying more than one layer. This extra layer can be done inside or outside the foundation wall. The perk of doing it inside is that this additional coat acts as a final layer of protection in case your foundation has water seepage issues. This makes the basement stay dry even if the foundation has moisture in it. Another major advantage is that this layer of tar can also help in creating an effective seal in the basement between the floor and the wall. Since these two parts are caste separately, the link between the floor and wall is the first place through which water can seep in. But with the use of a damp proofing spray inside the basement, this link gets effectively sealed.