We have mold and/or mildew in our finished basement. One contractor said this is because the drywall that was installed after we put in a perimeter drainage system was placed too close to the drains. The drainage system works well, and, as a result usually has some water in it. Between the water itself and the increase in relative humidity between the drywall and the cinder block of the foundation, mildew has an ideal environment in which to grow. The contractor said he could retrofit the basement system drain with a humidity extraction system. This will create negative air pressure within drainage system and will exhaust humidity to the exterior of the house. DOES THIS SOUND PLAUSIBLE TO ANYONE? It kind of makes sense to me, but I don't know how a humidity extraction system would actually work. Anyone ever hear of that?