Basement – How to attach wall on top of french drain in basement

If you're willing to put a little extra work into it, using screws instead of nails can really help make this kind of "light" framing much more durable. It's a little/lot more time consuming, depending on how much you love your power drill, but well worth the extra time, in my opinion.

Are the top and bottom plates already installed? Could you use a 2x2s for the top and bottom plates? Then you could nail (or screw) through from the outside of the plate into the stud.

2X12 is great, 3/4" plywood would be easier to handle and to drill through when you need to. Chalk your plate line where the wall will go on the room side, rip your plywood to go to the basement wall and 1/4" shy of the chalk line. That way when you set your upper plate you can still see the line to accurately set your wall. To answer your question, using nails will work, it is only fireblocking, you only really need enough to keep it up, since it is not structural, but do it anyway. Screws would work better, especially if it needs to be adjusted after it is up in place, and you see it needs to move a bit, it does happen. Shear or expansion should not be a concern. material usually shrinks once installed.