Hi, I live in Southwest Indiana and the basement to our home has no insulation with a cinderblock wall that they have either applied white paint or drylok to, can't tell though. The basement is also a walkout so three sides are exposed to air while the front of the house is underground. My question is should I apply 2 inch foam board to the inside of the wall or leave a gap for air? I understand mold will not grow on the board but I am afraid that there are very small cracks in the mortar in-between some of the blocks and don't know if this will affect anything.. I found a tiny stream of light coming through only one block and had to seal it. Rain does not get directly on the walls and the crack was so small that nothing comes through. Sorry for the rambling but I wanted to give you as much information as possible. Thanks for any help you can provide.