When we moved in, we hired a contractor to build walls in the finished basement. There was no dampness then, but now, 3 years later, it's all damp, need dehumidifiers running all spring/summer. There is commercial tile in all the rooms, but with age they are all broken or coming up, allowing moisture and a funky smell. These rooms were bedrooms, but I can't use them as such. The problem is the floor, not the walls. How do I go about waterproofing? I would like to do this myself. There is enough headroom to build up...any info is appreciated.