As the post reads, I keep on reading conflicting information on what type of product to use when insulating interior basement walls, and whether or not to use a vapor barrier. (Had a thread up regarding my furnace, but didn't want to confuse things) Seems like its not a cut dry answer, as it depends on your climate) 1.) I have not completed a heat loss calculation yet (thanks for the tip), but my question is mainly on whether to use rigid foam insulation or bat type insulation. 2.) Also, in the spring/summer, I will be taping plastic to the walls and floor of the basement to determine if I have a moisture issue or condensation issue. (Summertime it smells musty, but no signs of water/leaking....never any puddles after heavy rains) Foundation is completely below grade, and the ceiling joists in the basement are insulated with R19 Bat insulation. We will be finishing off 2/3rds of the basement. I have been monitoring temps in the basement, and the coldest I have seen is 53F when it was about 13F outside. (Temps are being taken from the far corner of the basement, furthest away from any light/furnace etc..) Some things I read states that R10 is needed for the basement, other items I see is R19 is needed. I would like to go with the rigid foam board insulation, but its max is about R8 for 2" think, so I guess I would be putting up additional layers. (The reason I am thinking about rigid vs bat is that even though we don't get water, and I don't think we have a moisture issue, it does get a musty smell downstairs, and have read that the regid is better versus moisture.) Again, just looking to see what others have done as I have read so many articles my head is starting to spin, and many of them conflict each other. Thanks.