I have a 20 year old house (which is a basic colonial box). The basement has a standard poured concrete exterior wall. Against the concrete exterior wall, they framed a standard wood 2 x 4 wall, filled the bays with fiberglass insulation and covered it all with a plastic sheet, which I guess is a moisture barrier of sorts. I would like to rip out the insulation and framed wall and replace it all with foam boards (DOW Thermax). My question is, how do I know that the framed wall is not load bearing in any way? I'm 99.9% sure from what I've read that it's the concrete wall holding up the house and the framed wall is just there to hold the insulation in place and possibly to add sheetrock to in the future.
I know that people might be nervous to answer questions about load bearing walls. I'm just looking for some general advice rather than a definitive answer.
EDIT: Here's a photo of the rim joist area. The framed wall at the front is the one I'd like to remove. From the answer below, it sounds like the joists are indeed sitting on the concrete wall.
EDIT 2: Somebody commented that I have no insulation in the rim joist. I actually pulled out the fiberglass to take this photo. I then replaced it with a block of 2" XPS foam board and used spray foam around the edge. I luckily have access to a thermal imager from my employer, so I took some images. Here's an image of no insulation (lots of heat loss):
Here's the original fiberglass. It does a good job, though there are some obvious cold spots from air leakage:
Here's the new 2" of XPS with spray foam around the perimeter. It also does a good job and it's more even. However, I'm surprised that there are still cold spots around the edge. It was tough to maneuver the spray foam gun in the tight area and I may not have done the best job:
Finally, here's a side by side of a fiberglass next to XPS:
Overall, I'm not sure there's a big enough improvement to warrant the cost. I think I could do a better job with the spray foam and a second piece of foam would obviously improve things. Aesthetically, I do like the clean look of the foam boards.
Getting back to the original question, here's a photo of the framed wall with the fiberglass insulation. Again, the fiberglass does a decent job, but there are some cold spots.