Foam and Batt Pole Barn insulation question

[worldrider555]

I've read and read and read about this topic and can't seem to find a definitive answer.

I am in the process of insulating my 30x40 polebarn in Pennsylvania. My original plan was to put 1.5 inch XPS foam in between the girts against the metal, sealed at all seams with greatstuff foam, and then I planned to frame a 2x4 wall in between the poles and place R-19 kraft face fiberglass. Then plywood as a wallboard.

Some of the reading I've done makes me question whether I should use the kraft face R-19 vs unfaced. I've read that could trap moisure in the wall as there would be 2 vapor barriers, but I've also read that the 1.5 inch xps is semi permeable as is the kraft paper. Any opinions.


One other question I have is on the first wall I did, I spray foamed all the gaps at the floor and the ceiling where the metal meets the studs. I also sealed the gap where the 2 different color metals meet/trim. Should I continue to seal these? Or keep them unsealed so any moisture can escape from between the foam panels and metal.

Thanks for all of your help!

 

[theoldwizard1]

I don't understand why you are doing 3 steps: 1) foaming the gaps/cracks, 2) XPS and then 3) fiberglass. Cutting and fitting the XPS is a pain.

If you did a good job with your gap/crack foaming, you will have no worries with and kind of vapor.

Personally, I would pay to have 2" of spray foam applied to the entire inside and then just go with batts.

 

[worldrider555]

I would have spray foamed it but I was worried about rust issues, which I read about on the boards.

 

[Fueler]

Do your walls have no insulation at the moment?

What I did.
Mine had that outside wrap insulation that wasn't all that thick or modern.
I did not want to give up any floor space.
I used 2" Styrofoam from Menards in between the girts and then put up my OSB wall.
I did seal at the edges of the boards.

If I received a do over and was not worried about losing some inches of floor space I would do the following.
I would use Rockwool (Roxul). I have used it in my home and it is great to work with and works great.

https://www.homedepot.com/p/ROCKWOO...att-15-in-x-47-in-12-bag-RXCB301525/205972559

You can pack this stuff in there tight enough as not have to fool with any extra spray foaming.

 

[toyotadriver]

I did something similar but with a stick framed shop. I did use the paper faced fiberglass between the studs. Similar climate. Works fine.

 

[yeldogt]

I've read and read and read about this topic and can't seem to find a definitive answer.

I am in the process of insulating my 30x40 polebarn in Pennsylvania. My original plan was to put 1.5 inch XPS foam in between the girts against the metal, sealed at all seams with greatstuff foam, and then I planned to frame a 2x4 wall in between the poles and place R-19 kraft face fiberglass. Then plywood as a wallboard.

Some of the reading I've done makes me question whether I should use the kraft face R-19 vs unfaced. I've read that could trap moisure in the wall as there would be 2 vapor barriers, but I've also read that the 1.5 inch xps is semi permeable as is the kraft paper. Any opinions.


One other question I have is on the first wall I did, I spray foamed all the gaps at the floor and the ceiling where the metal meets the studs. I also sealed the gap where the 2 different color metals meet/trim. Should I continue to seal these? Or keep them unsealed so any moisture can escape from between the foam panels and metal.

Thanks for all of your help!

I use spray foam all the time ... I have never built a pole barn and with all the various designs available being specific is not something that's possible online. Nothing works like foam .... if you have the budget ........call a couple of installers and get a price and recommendation. Also -- where is the design for the building coming from. Unless it's odd -- it's been foamed somewhere ..

 

[Natty Bumppo]

What you are thinking about doing sounds almost exactly like what I did. I used 2" polyiso in between the posts up against the girts, foamed all the seams, and then studded out between the posts with 2x3's. That brought me out flush with my 6x6 posts.
I then used 1x12 shiplap pine horizontally on the walls. I don't have many pics, but I'll attach a few.

Not sure how toasty you want to get your barn, but I will say that with 2" of polyiso my barn gets T-shirt warm on the coldest days with nothing but a portable buddy heater. IMHO I don't think you need the fiberglas.

One tip...if you haven't wired your barn yet, do it before you add the polyiso and frame out the walls. I ran all of my wire on top of the girts. Made it easy and quick to runs lots of wire. No holes to drill!

 

[dcg9381]

I would have spray foamed it but I was worried about rust issues, which I read about on the boards.

I'm in the south and have seen probably 30 of these steel buildings done with foam, some of them 10 years old. Haven't seen the foam cause rust. Might be a climate thing - not 100% sure. Foam, if applied correctly, is very consistent...

 

[4EyedTurd]

I’m curious about the same thing, except my shop is all metal. I’ve thought about the foam panels, spray foam the edges, batts and osb a few sections at a time versus splurging for spray foam and done.