Cutting kerfs in the rigid foam will allow the panels to conform. I use a sharpened spackling knife to cut or score rigid foam. Works like a champ!
I was at the big box store today, and the R-Tech rigid foam now comes with a reflective metal reflective facer. This is the first time I've seen it. It helps with moisture control. Anyway... back to my dilema...
I noticed the fiberglass batting at 6.5" thickness has an R value of R-13. The rigid foam uses the term "effective R-value". To get close to an R-13, rigid foam needs a thickness approx. 2.5". Trying to figure out if there are any technical advantages of using rigid foam. The fiberglass seems easier to install, other than protecting exposed skin.
Product PDF
http://www.insulfoam.com/images/stor...4101_RT_CW.pdf