OOPS!! I would seal the concrete basement floor
http://www.ardexamericas.com/en-us/P...s/MCULTRA.aspx
one more thing...go to a building supply and pick up a radon test kit...cheap...any reading above a four is a problem...may have to put in a remediation system....U be surprised how many houses with finished basements have high radon problems...we sell a lot of real estate and some homes have to have the system put in in order to sell...cost approximately 1,200 bucks for a contractor to install...good selling feature if U ever go to sell...most installers guarantee them.