We moved a 100 year-old schoolhouse to our property and set it on a concrete slab and two courses of concrete block. While we are repairing the floor, we've noticed the slab "sweating" a bit. I don't know if this is moisture passing though the concrete as the frost leaves the ground (happy early spring!) or condensation from the humid air (since there is a 7x7 foot hole in the floor)...

We have an access door at the back of foundation to get into the crawl space. The schoolhouse will be (mostly) conditioned, but there may be a month or three in the winter when it is closed up and not heated.

Do we need to be concerned about the moisture on the slab? There is no ventilation in the crawl space and we are worried that over time this could lead to moisture/mold/mildew issues. Thanks!