40ft high cube

Finished interior width with 2x4 walls, 85", 2x3 walls 86"

I am going to frame mine out with 2x3 footers and headers with 2x4 studs in the ribs. The ceiling will be 2x4s tied into the walls with hurricane clips, only because I am using screws versus nails for construction. Once the walls, ceiling, wiring and plumbing are in place, I am going to have the member from the fishing forum spray foam it 100% to the face of the studs, because I will be living in mine full time once it is complete. There will be no exterior windows or doors, entry will be thru the original doorway, for security purposes. If you use closed cell spray foam, there is no reason to have ventilation between the interior and exterior walls, because there is no way for the condensation to form. The ventilation for the interior is simple, I will be using an automatic controlled exhaust system with a humidistat, a dual zone dehumidifier mini split system with heat pump.

Condensation is your biggest enemy, so no gas appliances, not to mention the carbon monoxide poisoning. Loose batt insulation is a no go as well for the same reasons, it allows condensation to form between the walls. I have researched this ad nauseum, if you want to PM me, I will get you my contact