Let us know how it works out. Our house had an un-insulated basement.
So, the big wall of my shop was just 8" of bare concrete on both
sides. I applied 2 layers of 2" insulation foam to the exterior
of the wall, expecting a big improvement in heating bills. I was
disappointed that I really couldn't find any decrease in bills.
On the other hand, I really FEEL a difference working there in the
winter. I used to have to wear a jacket, now it usually is comfortable
in just shirtsleeves.
Later, we had an energy consultant come in and find all the leaks,
and I ripped the walls apart and sealed a bunch of leaks, mostly
around windows. Again, I couldn't really tell much of a difference.
Hope your results are better.
Jon