Sealing my attic space?


I have a small new construction house being built in southern mississippi. It has a metal roof with a vented ridge cap on top of the roof. My question is regarding insulation. I subcontracted out the insulation for the house and the installer said he would spray open cell in the walls and roof sheathing and closed cell under the house between 2x12 joists. Do I need to tell him to leave the vents open or seal the whole roof? Any ideas would be greatly appreciated.
Thanks in advance


Personally I do not like foam on the bottom of the roof deck. If it was my house I would insulate the attic floor. I have seen Several foamed roof decks rot out from condensation. If you have ridge and sofit vents you would want to fully baffle each bay before foaming to allow air circulation.


Agree 100% with the no foam against bottom side of sheathing.