I am expriencing a build up of moisture inside the exterior walls of my home. The home is 48 years old and the moisture is causing a mold smell in the house. We have checked all of the gutters and down spouting and they seem to be okay. We have no problems with ice damming. The walls are filled with 3 1/2 inches of paper backed insolation with the paper facing the living space. The house is built on a cement slab. We have been living in the house for 5 years and the problem started with in the last 8 months. We have had some contracter look at the house and they do not know exactly what is causing the problems. The interior walls are drywall with a painted surfaces. The outside of the house has vinyl siding. I hope someone has an idea of what is the problem. If you heard of this kind of thing before please help. We are at a loss.