I have a 1600 sq ft house with a Vaulted Ceiling in all rooms with large exposed beams. The roof is tin, on top of OSB, rafters are 2 x 8s. I am going to be doing T and G pine ceiling. What should I use to maximize R value. I would like to use fiberglass insulation. Do I need vents on ridge and eves? I really just need help figuring out the right thing to do. PLEASE ADVISE! Thank you for help

Personally I would go with a spray foam when insulating a vaulted ceiling. You'll get maximum insulation in that small area. I have asphalt shingles on top of plywood roof decking held up with 2x8s. I used icyene and I love the results thus far. No matter the season, I can keep two floors within 1 degree of each other and everything is on 1 zone. All my neighbors have a hard time heating and cooling the top floor of their cape cod except for me.

It is a one level house so no real issues there.. I have heard the spray in is good stuff to get in all the cracks and small spaces, just a little more pricey. I am wondering, what about ventilation.. is it required with the spray as it is in the fiberglass insulation?

From what I've seen on home improvement shows and from what I've read in "This Old House" as well as other literature, you do not have to ventilate the roof if you are spraying the foam directly to the underside of the roof decking. This is what I did in my house. The cavities between the 2x8s were completely filled with icyene and then the foam was trimmed back to be flush with the 2x8s. I have had no problems in the past two years... and all ice damming has been eliminated.

This being said, I would still contact the manufacturer of whatever material you use since there are so many spray foams out there.