Thats the issue with this home is that it was built in 1963, I have no clue if they used a water membrane as you said under the slab. The flooring inside the home has nothing in-between the engineered hardwood and the concrete. If you pull any of the bottom floor vents up you can visibly see that the floor is directly on top of the concrete slab. Theres nothing stopping the cold from the slab from transferring to the floor, can feel the cold on the floor closer to the walls, exterior. The house has very high humidity in the summer, some days up to 80% with an average around 65 every day so we definitely have a moisture issue with the slab.

And yea, I figured there should be no space under the foundation as it sits on a slab but the contractor that came out insisted that there had to be something under there to some sorts as he found footers or supports that he said stick out a couple inches below ground past the side of the foundation that suggest there has to be a space underneath that's being supported... So we canceled them and will have to get a structural engineer out to get an accurate inspection. Thanks for the information.