Advice on insulating polebarn

[MopardudeWI]

Location: SE WI
Building: 20x30 Pole building
Current Insulation: Some sort of wrap or blanket that was installed before the metal was put on walls and roof. I assume the wrap is a vapor barrier as well as its plastic backed, and I been heating it in the winter so far with a propane torpedo and haven't seen any moisture inside. But i guess that doesn't mean there isn't any between the wrap and metal? Soffit is vented. Unsure if the cap at peak is vented as well yet haven't climbed up there yet to see.

My plan is to build 2x4 inner walls flush to the poles and will be adding ceiling joists to make it a 10ft ceiling. The insulation wrap that was put on during construction doesn't exactly fill the voids between the girts.

Option A: use 2x6 insulation which will leave air voids in the walls behind the 2x4's and between the girts where the wrap doesn't fill good.

Option B: Foam board flush with girts, compressing the wrap/blanket in order to do so. Than a second layer of foam board flush out to corner and secondary bracing. Than 2x4 insulation in the 2x4 part of the wall.

Option C: I am open to other ideas as long as its not to overly pricey or if it is pricey something I can do on my own when as I have the cash. I am not rich but I do see the value in putting a few dollars in to insulate it good so heating is cheaper.

Vapor barrier of course on inside and ceiling. Ceiling bats in the ceiling.

 

[Stnbrgn]

Have a look at my thread. I'm not saying it's the way to go but it may help with some of your questions or give you ideas.
Here's the link I hope it works.

https://www.garagejournal.com/forum/showthread.php?t=375560

 

[lakeroadster]

Current Insulation: Some sort of wrap or blanket that was installed before the metal was put on walls and roof. I assume the wrap is a vapor barrier .........

Vapor barrier of course on inside and ceiling. Ceiling bats in the ceiling.

Double vapor barrier could be a problem. Traps moisture, moisture freezes, etc.

Does the building have soffit and ridge vents?

I'd go with option A.. a lot less hassle than cutting and fitting all the foam board. I used the 2x4 and batts approach on one wall in my barn. See post #142, page 8 in my build thread link below.

Have a look at my thread. I'm not saying it's the way to go but it may help with some of your questions or give you ideas.
Here's the link I hope it works.

https://www.garagejournal.com/forum/showthread.php?t=375560

two page thread.. nothing about insulation... except the R14 roll up door?

 

[stm317]

If the wrap that they added is an insulation blanket, you don't want to compress it and should just do 'option A'. Be mindful of double vapor barriers as mentioned by lakeroadster

 

[shaggyant]

Why does everyone perpetuate the myth that insulation stops working if you compress it? It’s just not true. The North American Insulation Manufacturers Association even has a fact sheet on it.

http://insulationinstitute.org/wp-content/uploads/2016/08/Compressed_R_values.pdf

This is what they have to say:

“When you compress fiber glass batt insulation, the R-value per inch goes up, but the overall R-value goes down because you have less inches or thickness of insulation.” “R value decreases by roughly half the percentage of compression.”

So, what this means is that using thicker than depth insulation is much better than using thinner than depth and leaving an air space.

 

[bobbyjean]

option b-i did it that way...air sealed everything....yep everything...kicks *** and save's space and money...
sounds like you were thinking 2 inch foam...that's pricey..but it's r-20 plus the compressed layer...thats nice....get the great stuff and seal everything..good luck with it

 

[MopardudeWI]

I guess what defines a vapor barrier? I am just assuming its acting as a vapor barrier because its plastic backed and when I run my heater in there when its around freezing I haven't experienced any moisture in there yet. I also don't try to push it either. I will only kick on the heater in there if its around freezing and above. Like today when we are -10 I don't dare try to chance it and warm it. I know to many farmers around with metal building that talk about they can get it to rain in there shops when they run heat to work in them. I have woodworking equips with cast iron tables I would rather not chance making it rain.

Is insulation with paper backing considered a vapor barrier?

 

[stm317]

A proper insulation system usually has a moisture barrier on the outside (something like Tyvek/Housewrap/etc), and a vapor barrier on whichever side of the wall is warm most of the time. In your case, that would be the inside of the wall. The paper facing on insulation acts as a vapor barrier. Plastic sheeting is another commonly used vapor barrier.