Vapor barrier or not?

[wantacoe]

I am using the pictured insulation sheets on the ceiling of my pole building. I will be using metal roofing for the ceiling. Do I need a vapor barrier with this type of insulation? Also on the walls I will be using the same insulation with OSB. Will that need a vapor barrier? Thanks

 

[NUTTSGT]

Does it have a foil face to it ? If it does, I would tape those joints and call it good.

 

[wantacoe]

It does not have a foil face. It is kind of like a roofing felt surface.

 

[jack stand]

How thick will the wall insulation be and what's Morton's plan for the ceiling?

 

[kumquat]

If the inside is heated, then yes.

 

[jack stand]

Not necessarily true with foam for insulation. It's important to have enough foam (depth) so that the dew point is within the foam. BUT his foam job needs to be fully sealed at all joints and edges.
2" should be enough.
I don't know how I involved Morton in this in my other response. Either I need my eyes checked or a "checkup from the neckup"

 

[wantacoe]

The insulation is 2 1/2" thick and I have it doubled up so it is 5". That is for the ceiling and walls. LOL, you did lose me with the Morton comment.

 

[jack stand]

I did this in my shop and house. Buy a foam gun ((about $40) and the screw on foam cans and some cleaner. You can stop and start days and weeks apart unlike the one use cans and the stupid straw. Foam in each layer and from what I've gathered that effectively is your moisture barrier.
I used 1 1/2" (used) foam, but 1 layer in between the wall girts. I built on a foundation for frost reasons and framed with conventional 16" oc and put my 2nd layer in between the studs. There's enough room for r13 fg left.
Of course I moved in before it was finished....
It's still that way
I did tyvek under the metal but that's NOT a vapor barrier, going on 12 years and I just opened a wall up to install a window a/c through the wall. No signs of any problems.

 

[67CarGuy]

Don't install a Class 1 vapor retarder on the interior side of air permeable insulation. If that's closed cell foam (can't tell from the photos, but looks like it might be closed cell) then you likely don't need the vapor barrier anyways.

You're in IL, how's the humidity in the summer? Humidity, like heat (energy) goes from more to less. So if you have A/C in there and drop the relative humidity in your garage below what it is outside, it'll try to draw the humidity from outside in so that it can equalize. The opposite in the winter - your space will be more humid than outside, so you'll have moisture drive towards the outside. All that to say, @jack stand is right about the dew point. You want your wall to be able to dry in one direction or the other (to the interior or exterior), and any bulk water that might get into the wall to have an easy way to get out.