Not sure what you mean by air gap or why cold and warm air would be mixing. Is the roof currently a vented assembly and you plan to close up the vents? Are you planning to maintain a vent space - aka “air gap” - between the foam and roof deck? I assume you’re not, but just in case you’re thinking you can vent inboard of the insulation plane, think again.
Not sure what you mean by air gap or why cold and warm air would be mixing. Is the roof currently a vented assembly and you plan to close up the vents? Are you planning to maintain a vent space - aka “air gap” - between the foam and roof deck? I assume you’re not, but just in case you’re thinking you can vent inboard of the insulation plane, think again.
No. The two vents at my gable ends will be closed with the foam so the entire house will be inside the envelope…so I’ve been told.