Hi KarenAnne,
My hubby (Tool Man) and I insulated the back wall of our garage in Sept. using the Insulpink foam (
http://secure.owenscorning.net/Portal/uploads/document/20040720/58103.pdf). It was very easy and not too expensive. We have a daylight basement, half below grade and the wall we insulated was below. First we put two coats of the UGL latex Drylok paint - that took one weekend. The following weekend we applied the 1 1/2 inch Insulfoam. The boards are 24" wide and 8 ft. high. They are attached to the wall using 1" x 2" furring strip boards every 24" and concrete screws. Finally, you can install electrical wiring very easily by running the Romex along the furring strips and using shallow electrical boxes. Being that the foam is very flammable, you must cover it with sheetrock. We had the wall complete in 3 days, well not quite - we tend to sleep in on weekends.
I can't tell you what a difference this has made in the garage. It's much drier, no more mustiness and stays much warmer than before. Plus we get to take the tax credit on the insulation for this year.
Now in NJ the minimum insulation value is R-8, but in NH and please double check this, it looks like if you use this continuous insulation system, you need to use the 2" insulation boards which are R-10. If you decide to use studs with cavity insulation, like fiberglass, you need R-11.
How much did it cost us to do the 20 foot by 8 foot wall? Here's what we got from the Depot:
2 gallons Drylok paint: $44.00 (actually used 1.25 gallsons)
10 1" x 2" furring strips: $ 9.00
10 1.5" Insulpink boards $117.00 (2" boards would cost about $32 more)
1 box 75 Tapcon screws $14.00
5/8" firerated sheetrock $59.00 (1/2 inch blue board would cost about $65 more)
Total $243
Good luck with your project, it will be well worth doing!!