This may prove to be counterproductive if the caps do not insulate. The wood will still get cold and collect moisture, only to be trapped inside the caps. The moisture is not coming from the ground but from the air. Coating them, however, would keep the moisture out and protect them.
A better option would be to seal off your basement and keep the moisture down with a dehumidifier and AC unit. If moisture is collecting, you probably will have a lot of other issues.