I will be insulating my garage this weekend and have had a couple different people tell me different things. So i'm looking to clear up some things.

The garage is 40X22X12 with walls that are 2X6, and rafters are that are 2X4.

I'm going to use R19 (6 1/2" deep X 15" wide) on the walls, and then drywall over that - no biggy here.

The roof, however, is different. I thought i could just use insulation in between the rafters in the roof, much like the walls, but someone told me that the roof needs to be left alone (no insulation against it) so it is the same temp as outside. which to me seems odd, because owens corning has illustrations of using insulation in rafters on thier web site (the same way i would use them in my garage).

For Example!

[img]http://chaordicconsulting.com/bp/Erik/Pictures/Erik/Houses/10mile/insulation.gif[/img]

I was planning on using R13 Foil insulation (about 1/8" thick) first inbetween the rafters in the roof, and then using R13 fiber insulation over that (remember the rafters are only 3 1/2" thick, so r19/21 is out of the question), and then finally using 2" thick R8 polyboard to cover everything up, giving me a nice white ceiling with a total R value of 34.

Now, will this work?