Determining ventalation

I am looking at a roof deck that has cathedral ceilings and the decking is very sturdy for the age of the building. The problem? No venting. I would love to install ridge vent to vent every rafter spacing but its the issue of does it need it? no gable vents either. Never seen anything like it. I know you can spray foam insulation to fill the voids in the rafters therefore no need for venting but that is not the case here, just bat insulation. what gives. any pointers? i am wanting to make sure the manufactures warranty sticks, CT.

We had to tear off sheathing,strap it out then sheathing back on top of strapping then ridge vents,on a simmaler roof.

I’ve seen vent issues act like a leaky roof. One customer complained that his new roof was leaking, but only when the sun was shining.

I’d recommend some sort of ventilation to the rafter bays. Ideally ridge vent, soffit vent(s), and propa-vent. If the cathedral ceiling has enough of a flat top, you might get away with gable vents.

I would strongly advise against sealing it tight with spray foam for the same reasons.

Good Luck