I don't know the technical terms, but above the cement walls, and below the main floor of the house I noticed today that if I remove the insulation that exposes the plywood, it's all wet and turning black with mold. My house is 3 years old. I use a dehumidifier in the summer, but in the winter the dehumidifier freezes up. The humidity level now is 43% according to my gage so I wasn't concerned about using it in the winter anyway. Is this a humidity problem or something else. I'm remodeling my basement, thus coming across the problem. Before I drywall the ceiling, I want to make sure I'm not covering something I should get fixed. Any advise would be greatly appreciated. I plan to talk to the builder about it Monday, but I expect zero cooperation. Txs!