Pole Barn Insulation

[UpNorther]

Hello all,
Im new to the board, been catching up on older threads for a week now mostly about insulating. I saw many posts but none were the same 'hybrid' insulation I'm thinking about, so I wanted to ask all of you for thoughts and advice.
Recently got a 40x48' pole barn shell up and plan on heating it through the winter months at about 50 deg then a woodstove inside for occasional bumps up in heat.
I plan on installing radiant floor heat and slab in this summer. Then walls and ceiling insulated and sheeted after.
I live in central Minnesota, the last week the high temp has been -4 f, so insulation is important. Also like others, I checked spray closed cell foam and found how expensive it is.
If I strictly batted the walls, I'd worry about air gaps and moisture.
If I blew the walls, I'd worry about settling and moisture.
My thought is: from the inside, use 2" styrofoam nailed onto the existing girts, taped or foamed seams. Then nail on the (second) inside girts, and use 24" R19 between the inside of them.

The rigid styro will be my moisture barrier against the steel siding also have 1 1/2" gap away from it.
Total R value should be R10 styro + R19 batts = R29 sidewalls.

Hybrid R29 cost approx is $2,300 total
Closed cell 3" R21 was $5,700 bid

Any thoughts are appreciated, thanks

 

[matt_i]

Dont forget to insulate under the slab, and slab edges ideally, with XPS.

 

[carcajou]

If it was mine i would spray foam at least an inch thick to seal everything up well. If you want to lighten the final cost you could use fiberglass bats to finish up to the r rating your after. From experience, i live where it gets cold too.

 

[52wrench]

I did similar to you. Insulation board between the girts then studded between the posts with 2x6s and then glass batts then a plastic vapor barrier then drywall. You need a continuous plastic vapor barrier over all of the inside, don't rely on just the taped seams.

 

[bjcouche]

I have a 40dx64wx12h pole building in Ohio and I had the inside metal walls and roof spray foamed at about 2". That seemed to work very well. In addition I'm adding R19 batts on top of that but it may not be necessary. There's a reason spray foam is so much more expensive, It's worth it. As hard as you will try to air seal with plastic tape, fiberglass etc. you will still have lots of air blowing through your walls, especially in a pole building. Since I had it spray foamed, my building no longer bangs, pings and pops with every cloud that passes overhead or tiny gust of wind. The foam sprayed directly on the metal makes the metal on the building extremely sturdy. Take your fist and bang on your wall and it will sound like you're banging on a huge steel drum. Bang on my wall and all you hear is a dull thud, like banging on drywall.

Because the OP is in Minnesota, he will need a minimum of 2" of closed cell to be considered a vapor barrier.

It will take a lot of time to cut all those pieces of rigid foam, and a lot of time taping up all the cracks, installing the foam, and then the fiberglass... Remember your time is worth something, you could spend your time working with rigid foam, or work some more overtime at work and get a better insulated building with spray foam. After having my building spray foamed, I've become a fan.

Brian

 

[Autorotica]

The biggest value in spraying insulation is the continuous air leak barrier. Dont get hung up on the R value number. I did roofing foam boards in my shed because I am cheap and being the masochist that I am, I enjoy working on my shack.

I paid about a dime a board foot compared to a dollar a board foot for spray foam. Keep in mind that mine does have air leaks and is not as good as the spray. I probably have 300 hours in doing my building but I have no doubt I have the absolute best I could get for the $ I spent.

You will never regret spending good money on the right product. It just has to be right for you.

Chris

 

[Voi]

My thought is: from the inside, use 2" styrofoam nailed onto the existing girts, taped or foamed seams. Then nail on the (second) inside girts, and use 24" R19 between the inside of them.

Are your columns thick enough for 2" of foam plus R-19?

You mention R-10 for 2" of Styrofoam (EPS) but I assume you mean XPS? That's R-10 and better suited for what you want to do, IMO.

I don't know what your column spacing is or what you're considering for interior sheathing but I'd at least consider using the wide blankets instead of nailing in all those extra (bookshelf?) girts.

 

[bearskinner]

You are worth spending the $$ on yourself and your own comfort. You will not regret spray foaming the whole inside. Or save all your money, and when you pass on, your kids will spend it for you.

 

[wagspe208]

I have to agree on spray foam. I bit the bullet and did it. I also have radiant heat in the shop. You can walk into my shop right now, touch the foam insualtion... it is room temp. I find it amazing.
Air gaps is the other huge deal.
ALSO, lower ceiling as much as possible. I put metal under my trusses, sprayed 4" open cell on that. Easy to heat.
I tried heating it last year without the ceiling in... I could have burned a train load of wood a week and not be heated.
Wags

I have been there... done that... shop more sprayers. I think I paid about 6k for a 50 x 72 x 12' high.

 

[HemiRamOn22s]

2-3" of spray foam on the walls and then blow in insulation in the ceiling 18" thick. I barely have to heat my pole barn in the winter. Stays around 50 with barely any heat and its 60'x104' with 16' ceilings. Its not as cold as it is up north but we do get temperature in the single digits a few times throughout the winter.

The spray foam also increases the structural stability of the building 300%