I read somewhere that cinder block needs to breathe because it it needs to vent moisture. So now that I waterproofed the outside of my basement wall (excavated and installed sheet drain and pipe) should I be using Thoroseal (or something like it) on the inside?? Will this prevent the block from venting natural moisture? If I don't seal the inside, will I be able to insulate the wall? When I stripped off the old drywall I found that the previous owner had installed a sheet of plastic between the block and the framing. I had to take this down so my wall would dry out. I imagine the Thoroseal will take the place of the plastic.