Pole Barn Insulation and Vapor Barrier NJ

[thorthefrugal]

First time posting here. I'm trying to figure out the best way to insulate my 40x60x14 pole barn. The pole barn was built with no exterior house wrap. I glued up 1.5" polystyrene to the girts, foamed and taped the seams, and then nailed 2x4 bookshelf girts between the posts. I plan on finishing the bottom 8 feet of the walls with plywood and then the remaining 6 feet with metal siding. If I went with fiberglass insulation, should I put a vapor barrier between the interior panels and the insulation? I am located in southern NJ. Thanks!

 

[jack stand]

Welcome to GJ!
Will you be heating this and if sow, how?
You've done well with the foam and I've always heard that you want your dew point within the foam to not worry about a vapor barrier. (that you've created with the foam/foil layer)
You might consider an additional layer of foam on the top of what's done. Add up your advertised R value of existing foam and whatever you might add to estimate that value.
With a little checking around there always seems to be someone selling foam 2nds or "recycled" foam from commercial re roofing jobs. This is what I've used quite a few times over the years.
With the 2nds, it's usually a panel thickness issue, like 2" panels that are a little thicker or thinner than advertised. The used foam will have screw holes in it with some screw plates stuck on the panel. Also a chipped corner or broken paper/panel on one side but not completely broken in 2.
They're usually faced with a tar paper like surface.
It's hard to put your time and money into insulating and you have a great start.
You only pay for insulation once vs paying for the ever increasing price of energy for heating and cooling.

 

[thorthefrugal]

Welcome to GJ!
Will you be heating this and if sow, how?
You've done well with the foam and I've always heard that you want your dew point within the foam to not worry about a vapor barrier. (that you've created with the foam/foil layer)
You might consider an additional layer of foam on the top of what's done. Add up your advertised R value of existing foam and whatever you might add to estimate that value.
With a little checking around there always seems to be someone selling foam 2nds or "recycled" foam from commercial re roofing jobs. This is what I've used quite a few times over the years.
With the 2nds, it's usually a panel thickness issue, like 2" panels that are a little thicker or thinner than advertised. The used foam will have screw holes in it with some screw plates stuck on the panel. Also a chipped corner or broken paper/panel on one side but not completely broken in 2.
They're usually faced with a tar paper like surface.
It's hard to put your time and money into insulating and you have a great start.
You only pay for insulation once vs paying for the ever increasing price of energy for heating and cooling.

At this point, I am not planning on heating it yet due to money. As I save up, I am working on it one part at a time. Do you think another layer of foam would be a better than fiberglass?
I'll have to take a look around for seconds. I appreciate the kind words. Like you said, I want to make sure I am prepared down the road, cause heating and cooling costs around here are crazy right now.

 

[jack stand]

It would insure that (when you ultimately heat/cool this space)
that you don't want a moisture issue within the wall.
I'm not a scientist but I'd be concerned about condensation between fiberglass and the foam that you've got there. This wouldn't be an issue with more foam especially if you're foam is the white "coffee cup" type.
I don't remember the difference between polystyrene and polyurethane.

 

[thorthefrugal]

I got you. So would something like polyiso board work as well?

 

[jack stand]

I got you. So would something like polyiso board work as well?

That actually has the highest R/inch @ around R7. That's also what I find almost exclusively in the 2ns & recycled market.
The convenient thing is unless you're wanting to close in your walls right away, it's easily installed anytime giving you a chance to find a source.
I've done well with Craigslist and I hear that FB market place as well.
I just don't do or want anything to do with FB.

 

[cpakalolo]

First time posting here. I'm trying to figure out the best way to insulate my 40x60x14 pole barn. The pole barn was built with no exterior house wrap. I glued up 1.5" polystyrene to the girts, foamed and taped the seams, and then nailed 2x4 bookshelf girts between the posts. I plan on finishing the bottom 8 feet of the walls with plywood and then the remaining 6 feet with metal siding. If I went with fiberglass insulation, should I put a vapor barrier between the interior panels and the insulation? I am located in southern NJ. Thanks!

That polystyrene is a vapor barrier/insulation system of its own since you taped the seams. In New Jersey, you should have at least an R-4.5 capsulated insulation foam if it is against the exterior sheathing. If so, the vapor will not seek the cold surface and won't condense. It is ok to go over it since you already did your exterior envelope and your interior envelope with the same layer. You don't need house wrap. The water can only get to the inner side where the insulation has raised the temperature of the surface above the dew point of the inside air. It won't condense if it is not cooled. It cannot cool if it can't get to the sheathing.

 

[thorthefrugal]

That polystyrene is a vapor barrier/insulation system of its own since you taped the seams. In New Jersey, you should have at least an R-4.5 capsulated insulation foam if it is against the exterior sheathing. If so, the vapor will not seek the cold surface and won't condense. It is ok to go over it since you already did your exterior envelope and your interior envelope with the same layer. You don't need house wrap. The water can only get to the inner side where the insulation has raised the temperature of the surface above the dew point of the inside air. It won't condense if it is not cooled. It cannot cool if it can't get to the sheathing.

So are you saying that since the polystyrene acts as a vapor barrier, I could use fiberglass to fill the rest of it? I’ve been on the hunt for used or seconds polyiso, but have had no luck.

 

[cpakalolo]

Yes. Especially in floor joist pockets where the moisture goes right through the fiberglass. I would rather put up a full 1" of vapor impermeable board like extruded polystyrene. Bead board will usually have a vapor barrier layer on the surface. Remember, that the seams and edges should be caulked or the moisture goes around.