insulating pole barn walls

[Fibersport]

I have a 30 x 54 x 10' pole barn with no insulation. I'm starting to install a ceiling that will be from the inside up - drywall, vapor barrier and blown in insulation eventually. I have an opportunity to buy some foam panels now that are either 3" or 4" thick that I might pick up for the walls. My posts are made of three 2x6's so my depth is about 5-1/2" to the girts (I think that's the name) with then another 1-1/2" for the girt thickness to the sheet metal siding. I plan on eventually finishing the inside of the walls too but with the insulation being thinner than the cavity, my question is if I need to have an air space in the walls, should it be on the outside or on the inside? I could build the walls with no cavity but I'm not sure if it really matters. I realize a cavity would probably become a home for mice and other critters so I'm thinking maybe it might be best to build it without any cavity, just wanted to get some other opinions.

 

[stm317]

I'd try and build it without any cavity, unless you need the cavity to run wiring, plumbing, etc. Air is a lousy insulator compared to insulation, so filling the cavity with as much insulation as possible will give you a better result.

 

[unionvillecountryboy]

Air is an excellent insulator, the movement of air is bad.

 

[bullnerd]

I would try to find blanket insulation in your area.

You can se how I did mine in my build in the sig.

I copied how Morton buildings does it.

Just my opinion, not a pro.

 

[earthmover1980]

Talk to a insulation contractor about sprayed in foam insulation! The best sealing characteristics, and highest R value. Well worth the money! We love ours

 

[d300]

I'd ask what your final goal is. Spray foam is the absolute best for many reasons but has a high up-front cost. As mentioned, air movement is the killer of R-value, regardless of the type of insulation. This is why spray works so well, it seals virtually every nook and cranny and there is no air movement. With that as a guide, use any insulation product you want and try to seal it up. With the surplus panels you have access to you can do a fair sealing job with lots-o-cans of touch-up foam. Assuming that the panels are hi-density foam then 3" will also be your vapor barrier.

 

[RGKSR]

I did spray foam in my pole barn. I also put up 5/8 Sheetrock on the walls.

 

[jack stand]

I'd ask what your final goal is. Spray foam is the absolute best for many reasons but has a high up-front cost. As mentioned, air movement is the killer of R-value, regardless of the type of insulation. This is why spray works so well, it seals virtually every nook and cranny and there is no air movement. With that as a guide, use any insulation product you want and try to seal it up. With the surplus panels you have access to you can do a fair sealing job with lots-o-cans of touch-up foam. Assuming that the panels are hi-density foam then 3" will also be your vapor barrier.

This^^
If you plan on staying there, I'd stuff all the rigid foam you can in there. If you put 4" up against your wall girts, then toenail in 2x4's flat ways you should "flush out" with your posts. It it were me, I'd pay retail if I had to for some 1 1/2" foam (ISO is the best r value) to cut (and foam all edges) in between your flat 2x4's. Cut tight & foamed you'll have 5.5" of foam that will make heating & cooling much easier. You'll need these 2x4's to hang your interior wall finish material (drywall) anyway. Your electrical can be installed first running on the outside of the posts under the siding in the 1 1/2" space and then through your insulation. Do it! well worth the expense (and time/hassle)

edit; I'd find some long screws to place a few through the flat 2x4's into the wall girts along with some construction adhesive to keep those flat "studs" from mis behaving.

 

[Buck41]

I put 4x8x 5 1/2” thick of styrofoam panels with osb strip every 24 inches full length. Just like SIPs panels. Just use long screws an screw in to the horizontal girts . Outstanding results. My ceiling was blown in at R-49 .My barn is 40x64x14’. It worked out very well and very fast. I didn’t have to do any framing

 

[Diesel Dan]

Look into PEBS blankets as well. R19 rolls up to 8' wide.