Your problem, as you should have guessed, is too much moisture. Your main concern is to find out where the moisture is coming from. If you have a bare section of concrete available, check the moisture content. Clean @ a 1 foot square or more area thoroughly. Allow it to dry and then place a piece of plastic,preferably clear, on the floor and tape the edges for an airtight seal. Check back in a day or two for moisture under the plastic. If you find none then the moisture is being produced from inside of your house. If there is moisture then you will have to go outside and try to figure out how the moisture is entering your house. Some examples: improper ground slope, bad gutters, broken storm sewer, etc. HAPPY HUNTING!!!!!