I have been faced with the same problem recently and found a number of companies online that offer solutions of varying types. Most fall into two (2) categories. One attacks the problem under the basement floor, the other on top of the floor. I like the latter best. It is far less cost and mess. One company in particular offered what I felt was the best sounding product. They have been around for over 20 years and are nation wide. You can install the system yourself or have them do it. You can find them online at www.REALDRY.com Good luck.