Pole barn insulation - foam + batts?

[Dstyduhar]

Good afternoon,

I know this subject has been beaten to death but Im at a crossroads here and curious to hear from others about their insulation experience. Building is 40x50 with 14' sidewall. I'm in Northern NC and it only gets down to < 20 degree temps on occasion. I plan to heat with a wood stove. Metal working, wood working, car stuff, etc. Typical catch-all workshop for all the work around the farm.

Regarding the wall insulation, I initially planned to do the 1.5" thick foam between the girts and then frame an 8' 2x4 wall between posts and roll in R19, letting the fiberglass spill out behind the 2x4's. Above the 8 foot wall I would retrofit commerical girts in and roll fiberglass in horizontally. Foam (like everything) has really gone up in price so I'm trying to make sure I have a solid understanding of whether the foam is really worth the extra $$$? My building has that double bubble stuff between the tin and framing and although there is no real R value I think it did a good job keeping the drafts down. I have been out in the barn during some pretty heavy winds and can't feel much of anything inside the building.

I have a lead on some 4x8 Polyiso 1.5" foam at 20 bucks a sheet. Its around 8-9R value so that plus the R19 fiberglass is around R28 or so. I mean, is that overkill for a workshop? Our house has 2x4 walls with R15 Rockrool and its fine. What other benefits does the foam provide? Maybe prevent mice from using the girts are raceways in the building?

thanks for any feedback,

Drew

 

[Bears Fan]

Drew

I built a 30x40x12 pole building, I had 1 1/2" urethane R-10 closed cell foam sprayed on, then 5 1/2" R-19 fiberglass batt insulation installed, then covered it with visqueen and 1/2" OSB, with almost R-30 rating, this thing is awesome! I'm so glad I went this route it was well worth the extra money. the spray foam actual strengthens the structure, it is air tight, it made it so quiet inside you can't hear any noise outside and it heats up really quick, I installed a 125,000 BTU Modine Hot Dawg propane heater, I can go from near zero degrees inside to 60 in about 20 minutes.

I'm so glad I went this way after the fact and was well worth the extra money.

Here's a link to my insulation part of the build

https://www.garagejournal.com/forum/threads/dabarn.316577/page-3

 

[theoldwizard1]

Spray foam all the joints/penetration, specially corners. This will keep wind out. After that any type of batt insulation is good. If you are willing to hang skrim and later cover with sheet rock/plywood, you can use blown in insulation.

Polyiso is great but it is flammable ! You sometimes can find USED polyiso foam boards cheap. You typically have to haul it yourself and the edges may require trimming.

 

[billconner]

I don't quite understand what's above 8' but you should not leave kraft paper exposed or polyethylene exposed.

Whether you do spray foam or use the poly iso and seal seams and joints with foam-in-a-can, I would think bookshelf girts all the way up with batts make sense.

A lot of insulation for NC maybe.

 

[Natty Bumppo]

I mean, is that overkill for a workshop?

Simple answer...yes. I have a similar shop on a 2,000' cold, windy plateau in the Northeast and all I have is 2" Polyiso in my walls. I can work out there on even the coldest January days and its comfortable. By comparison, my house has 2x6 walls and R19 insulation and it's also fine. So IMHO having BOTH 1.5" polyiso AND R19 in North Carolina is probably overkill.

It's certainly not going to hurt anything by putting in the polyiso if you can find a good deal and you don't mind putting it in.

 

[billconner]

Put in the poly iso, foam the seams, and attach ply or OSB or gypsum to the girts. More floor space and simple.

 

[Dstyduhar]

Thanks for the reponses. Im trying to kill two birds with one stone by framing 8' walls between the posts and also interior and then using the walls to set 2x10 joists on for a loft area in the gable end of my building. Will be ~14x40 loft.

When framing between walls, how would you guys attach the sill plate considering I have 1.5" XPS around the perimeter. The laminated posts are 5.25" so that only leaves 5.25-1.5 = 3.75" of concrete. I think there is not enough edge distance for wedge anchors. Tapcons maybe? It going to be sub freezing so appears too cold for epoxy anchors.

I saw where someone mentioned drilling a hole and pounding a pair of nails into the hole....i need to find the thread where they discussed that? Ideas?

thanks.

Drew

 

[Snip]

When I started framing the inside of my pole barn, (40x66x14) I attached my 2x4 PT sill plates using Tapcon screws. I ran a small bead of liquid nails underneath them just as a little extra. 2x4 walls flush with the front of the posts using R-19 with hopes fo fanning out behind the 2x4's.

 

[kj_mustang]

My loft (32w x 24L) is over the full width of my building and is supported by 2x12s attached to the posts. I framed my interior walls using horizontal 2x4s attached to the posts so didn't have to attach one to the floor . Just another option to consider.

 

[billconner]

In planning, don't forget that fiberglass looses some of its insulating value if not mostly snug in a cavity. 2x6 batts in 2x4 walls and gaps between batts and siding sheathing reduces effectiveness.

 

[Dstyduhar]

Thanks for the responses.

Loft support

Although I can definitely see the appeal, I'd rather not load the posts in my building and prefer to set the loft joists on top of the framed wall for that portion of the building. I plan to store some heavier **** up in this loft so I'm waffling between 2x4 and 2x6 walls, both between posts and interior. 2x10 joists with 12' free span and cantilevered over the interior wall a foot or so.

Sill plate

Regarding the concern with attaching the sill directly to the concrete (comment about commercial girts), the frost line here in NC is less than a foot so not worried about the floor heaving. The perimeter of my slab (between the posts and attached to inside of second skirt board has 1.5" xps foam that extends down below the frost line a few inches.

BillConner - Good point there. I was also going to ask about the insulation stackup and whether the fiberglass should be FACED or UNFACED with the Double bubble **** stapled to outside of girts

From outside in:

Metal siding
Double bubble - is this considered a vapor barrier?
2x4 girts - what should I do with the gap between the girts? Consensus seemed to be that was xps was overkill for my climate.
2x6 walls with fiberglass - Should it faced or unfaced?
1/2" drywall

thanks,

Drew

 

[billconner]

I mentioned the fiberglass filling the cavity in regard to stud size and post size. I'd rather the fiberglass butted against the bubble wrap so there is no air movement behind it.

In NC, assuming bubble is there, I'd go with unfaced batts so it can dry to inside since bubble wrap prevents drying outward. But what is inner wall covering?

 

[Dstyduhar]

Hi Bill,

The inner wall covering would be 1/2" drywall unless im not understanding the question.

The thing about fiberglass filling the cavity is it would need to be for a depth of 5.5" (Laminated 2x6 post) + 1.5" (2x4 girt) = ~7" depth wall. Obviously where the girts are located the insulation would be compressed to a depth of just the laminated post.

Unfaced batts made sense to me also. I worry about faced batts and trapping moisture in the walls.

thanks,

Drew

 

[billconner]

Yes - drywall would be fine. Plywood or metal liner panel and I might think about it. The drywall will allow moisture - most like from humid days and cranking AC - to dry inward.

Were it me, I'd consider compressing 8" batts so they are tight against siding. And use 2x6s 24" oc to enclose the batt on all 6 sides. I might say the heck with it if it cost too much (?) extra, but I'd consider it.

 

[Dstyduhar]

How about 1.5" xps between the girts and some r19 for the 2x6 walls??

by 8" batts do you mean for a 2x8 wall? Not seeing 8" online

thanks,

Drew

 

[billconner]

Yes to the xps between gifts. Not inexpensive.

I see the 8" R25 used to be more common but rare today. Found it at Menards (8 1/4" R25).

 

[Dstyduhar]

yeah the XPS prices are way up.

What happens if I just put R19 in there and there was an air gap between the girts? Im sure the R19 will fluff up a bit.

 

[Jbullfrog]

I ripped 2x4's in half and used a Ramshot to drive nails into the concrete at the bottom of my wall. My pole shed posts are 8' on center with short posts 4' on center for the grain wall. It was originally a flat storage for grain 6' deep. I had 2" of foam sprayed on the steel and girts before installing 5" of fiberglass and OSB. I didn't frame behind the osb since the posts are 4' apart, but i did screw a 2/4 at the seams between sheets. I screwed 2/4's to the short posts that run up to the header.

 

[billconner]

yeah the XPS prices are way up.

What happens if I just put R19 in there and there was an air gap between the girts? Im sure the R19 will fluff up a bit.

You simply won't get R19. Is it 1% or 10% or more? I don't know. If it's my house on the artic circle, it would be important. May no matter in a garage in NC.

 

[Dstyduhar]

I was speaking not so much about the r value but if it would cause issues leaving an air gap between the vapor barrier and insulation.

 

[billconner]

I was speaking not so much about the r value but if it would cause issues leaving an air gap between the vapor barrier and insulation.

The issues are, I believe, just a loss of R value.

 

[Williebeeguy]

Foam is good to stop air movement. Fiberglass still allows air movement. We built our 40x80 pole barn. We did 2" of spray foam on the entire thing and it's fantastic. Holds heat in well. We have in floor boiler lines and back up wood stoves for getting rid of scrap

 

[Jakemedic]

I used 8’ wide rolls of insulation fit perfectly between posts and eliminated the need to build stud walls. Main benefit is minimizing thermal break. Obviously needed to use a vapor barrier, and horizontal fraining members . Did that 2+ years ago, and have been very pleased,with the results.

 

[BlindViper]

I used 8’ wide rolls of insulation fit perfectly between posts and eliminated the need to build stud walls. Main benefit is minimizing thermal break. Obviously needed to use a vapor barrier, and horizontal fraining members . Did that 2+ years ago, and have been very pleased,with the results.

What insulation did you use and what was the r value?

 

[Jakemedic]

hello! This is the product I used to insulate my walls in my shop. It is 8’ wide rolls, easily cut with my brides electric knife. Washed it up afterwards and still worked for cutting the holiday ham. It is R19 and with a vapor barrier before covering the walls, worked amazing. The downside is the dealer I purchased it from said it is out of production till March of 2023. Not sure why. It was the best decision I made, hands down. No 2x4 walls. my thought process was if I were going to build walls inside walls, I may as well have built a stick build versus a post frame. Here is a picture and company name as well as my install, prior to finishing the walls. Note, I also decided to run my electric inside the walls, cause my building is a wood shop. Didn’t need any conduit on the exterior of the walls to collect dust.

without hesitation, I would wait and get this insulation, it created a nice insulation blanket. I don’t get anything from the company for recommending it. Contact them directly, and they will tell you where your local dealer is. They literally got back to me within 15 minutes of contacting them. Great product!
Jake