Is an air gap between foam and finished ceiling ok?

[Mokey-SKO]

Hello! I can't seem to find any consensus on ceilings, insulation and air gaps. My E450 shuttle came with a spray foamed ceiling between the aluminum ribs. My plan is to put furring strips up so I can attach 1/4 ply as a ceiling. This will create an almost inch or more air gap between the ceiling and the foam. Will this create condensation issues? Do I need vapour barrier? I have sound mat that I was going to run under the furring strips to prevent any thermal bridging. Opinions please!

 

[JA6net]

You'll thank yourself later if you fill that gap. Condensate forms less on foam, but could still happen. I'd be more focused on the benifit of an inch of insulation. Even stuffing it with rock wool or denim fluff would be a good plan.

 

[Mokey-SKO]

You'll thank yourself later if you fill that gap. Condensate forms less on foam, but could still happen. I'd be more focused on the benifit of an inch of insulation. Even stuffing it with rock wool or denim fluff would be a good plan.

Thank you! I actually ordered some thin fibreglass batting to go in the space. Why skip this small step and have big regrets later.

 

[TMartineau]

I would still add a vapor barrier between the insulation and the ceiling. Its just a piece of plastic and adds peace of mind. From all that I have read and with zero experience... lol Yes spray foam insulation is less likely to form condensation but not until its 2-3 inches thick. Just some food for thought.
Thomas