Wet basements can not be used fully and might endanger the building substance. We offer three methods for making basements usable again by applying a new, permanently safe waterproofing: From the outside with polymer-modified thick film sealants, mineral sealing slurries or a cold self-adhesive waterproofing membrane – whereby the entire external wall area is treated and thus protected from water penetration. Alternatively, the waterproofing can be done by installing the external waterproofing from the inside of the basement. This method can also be used at a later point in time, e.g. when a new subbasement is added to a house. In this case, the wall/bottom junction is waterproofed via injection.