Hello folks, first time poster so I will try to be detailed and specific with my question. I just had a thermal scan done of my 120 year old house and I have a wicked amount of heat radiating from my basement. The basement has a cement floor and is heated. The foundation from the bottom to about 4.5 feet upwards consists of sandstone blocks about 10-12 inches wide. On top of the rocks up another 2 feet of so are hollow cinder blocks and then the large 12 inche wide wooden sill. Ground level would approximately be where the cinder blocks start.
Since the cinder blocks are pretty much high, dry and exposed, any amount of water I get in the basement comes in the form of seeps through the porous sandstone blocks (mostly down low). Not a major amount of water ever comes in. What I plan on doing is bringing a 2x4 stud down from the top for a length of about 5 feet. This will take me 2 feet below ground level and onto the sandstone. I plan on putting R-20 bats in between the studding. My main question is, what should I used as a barrier to drape down against the cinder blocks and the 2 feet down I am going onto the sandstone blocks? I want something that will keep the bat insulation dry and functioning in the odd time that dampness will occur and I don't want issues with sweating or mold formation. The reason I am using bat insulation vs. simply gluing on rigid foam, is that I need something flexible. With the cinder blocks being about 8 inches wide and the sandstone being another 4 inches out from that, there is no way with out major air space to make this work. Will a heavy layer of poly 5 feet down suffice to drain any dampness?
I by no means am looking for a perfectly finished gyprocked basement. I simply want a 5 foot insulated section around my sill and covering this cold and exposed section of wall.
Any help or suggestions appreciated. I have looked at Tyvek drain wrap, but don't know if I am waisting my money when poly would suffice?