I'm thinking about insulating the tops of my basement concrete walls with 15x12" pieces of fiberglass insulation. The space between the top of the wall and the house floor is about 12" Would I use faced or unfaced insulation for this little area? What R rating would be best with cold Missouri winters?

I used a spray foam kit and it worked great. Sealed out the drafts and the cold.

The spry foam is great for sealing the corners and eliminating infiltration, but it gets unreasonable if you are filling many voids.. After that, you can use unface fiberglass in the spaces between to joists or between the rim joist and the first interior joist parallel to the exterior wall until you decide to finish the basement.

If you have a wall thicknes of 8" or more, you can use multiple layers, but do to pack the fiberglass in tighly, because this decreases the insulating properties of the fiberglass.

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Originally posted by SageBuilder:
I'm thinking about insulating the tops of my basement concrete walls with 15x12" pieces of fiberglass insulation. The space between the top of the wall and the house floor is about 12" Would I use faced or unfaced insulation for this little area? What R rating would be best with cold Missouri winters?

Unless you live in the US Coastal West or Gulf Coast South...Your basement will require a vapor barrier on the warm-in-winter-inside location in all cases.

For Missouri, your state energy code requires a vapor barrier on the warm-in-winter side.

Your R-value will be required to be at least R 10 if your basement walls are at least 50% or more below grade or R-19 if they are are at least 5-% or more above grade.

OK. I can put faced insulation in those spaces but from a practical perspective it will do nothing to stop vapor. With all the wiring, pipes, ducts, and AC lines running through those spaces there is no way to seal the facing to the floor joists to create an effective vapor barrier. In most places the vapor will simply go around the insulation and condense on the outside 2x12 if it wants to.

You are quite correct on that issue. But you need to do the best you can to stop as much moisture from reaching the exterior areas of the wall.

The tighter the fit the better the barrier will end up being.