I live in a slab house with one ring of concrete block showing on the outside of the house just below the vinyl siding. I also have pergo flooring in the whole house. The bedroom is the only room that does not cool in the summer and is too hot in the winter. It is also the only room with cold floors. On the outside of the bedroom ONLY is where the white mold is growing. It has no odor, but is powdery to the touch. My son-in-law says it's calcium, but I wonder since I'm nasal all the time. Could I have a leak in the slab? Or what could it be?