Insulation Help Needed

[Ron Petersen]

Looking for info on getting my new 12x24 Gambrel Roof Shed insulated. I am wanting to use the foam board due to cost and ease of use as well as being able to seal the edges with spray foam to prevent air leaks. I am in North Dakota where it gets down to the below zero temps. I want to be able to heat it all winter so I can keep my fridge and freezer out there as well as being able to work in it. Possibly smoking meats.
I am confused to the roof air venting to prevent moisture buildup. Currently the shed has no vents under the roof eave or top, it only has 2 small vents on each end.

Do I need to make vents or can I get away with just putting foam board between rafters and sealing with spray foam?
Roof has osb then steel on top. Walls are wood siding (not pressboard). Floors are foam board insulated. Floor is treated plywood which I will cover with either linoleum or something else.

Thank You for your help

[Chris Damm]

If you're using extruded polystyrene (pink or blue) don't worry about ventilation. Your door will allow enough air unless you built it like a refrigerator. I would built removable panels for your existing vents, open as necessary.

[Eric Keller]

you can insulate between the rafters and seal with foam, as proposed. Smoking meats may cause enough moisture to be a problem. Building inspectors and shingle manufacturers sometimes have a problem with doing this. In a house, with a fairly large movement of moisture, it takes careful detailing and possibly more insulation than you want to use. I'm currently putting up foam board in my basement, it's nice to work with.

[Ron Petersen]

I plan on building a cabint style smoker, it'll be more for low temp smoking, it'll have an exhaust vent to the outside. The real cooking is done outside.

Wasn't sure if I needed to add ventilation at the rafters with a 1" gap between the roof and foam board. If I can seal it like discussed, even better. Was going to seal with spray foam on the edges of the rafters and the edges of the foam board to create a tight seal.

I want to eventually cover the foamboard with either wood panels or thin 4" wood strips.