Why are you going with solid foam in the first place. It is not the best insulator. I would go with bat insulation--check the R value when you go shopping for it-- or sprayed foam. Unlike it's solid cousin the sprayed foam adheres to all surfaces and fills every nook and cranny. If you use bat insulation don't forget behind electrical boxes too.

You need a vapor barrier no matter what you use for insulation. It goes on the side that is warm in winter. In most cases that is after the insulation is installed and on the inside of the house, just behind the plaster or drywall. All seams and around electrical boxes must be sealed with a special tape made for this. What the vapor barrier does is to keep moisture from the house from getting into the insulation thus rendering it useless for insulating.

You'd probably can have this confirmed by posting in the building a home or one of the home forums.

We used Icynene, a spray in foam as mentioned above, in our homes exterior walls six years ago and though this home is more than twice as large as our last home we spend quite a bit less on heating and cooling it. I'd seen it done on some home show while we were still in the planning stages so we investigated it along with other typical insulation and felt it was the best for our home. That doesn't mean it would be the best for yours. You'll have to do some research, but you might want to check out the link to what we used and see for yourself. Oh and it's a green product.
I have no connection with the company, just like their product.

Here is a link that might be useful: Icynene

If you Google: Holmes on Homes Spray Foam

there are lots of sites to explain closed cell vs open cell.

BASF "Walltite" is a well known brand of closed cell spray foam.

The closed cell is much higher in R value which means less thickness is needed. Open cell takes up more room and may exert more curing pressure in areas of a structure where that isn't helpful.

Either one would be a good choice when compared to older methods and materials.

Here is a link that might be useful: a few facts in one place

Closed cell is the only way to go if it is appropriate for your applications--it think it would be.

We upgraded and used the closed cell spray foam in our current home, 2X4 exterior walls. Even though our home is nearly twice as big as our old home and our last home had 2X6 walls, plus an inch of sytro on the outside, our utility bills are now 1/3 lower even though the new home is bigger.

It is amazing stuff--you won't be disappointed.

Thanks for all the info I think we have made a decision we are going to use 2 inches of closed cell in the walls and beam ends and then use r-30 fiberglass in the ceiling I would love to spray the ceiling with open cell but its not going to happen the budget is to tight. along with the closed cell in the walls we will be adding r-8 in the walls to bring the R-value up a bit.