Shop Wall Insulation

[Steve Goetz]

This may be a thread on here, but I couldn't find exactly what I'm looking for. I'm in the process of framing in and insulating my (new to me) pole barn. it is a typically constructed post/frame with 2x4 purlins every 2' o/c with metal siding. I'm planning to insulate and then put purlins on the inside to attach some sort of panel-metal siding, T1-11, plywood...not sure yet. For between the purlins, I'm planning to put up Rockwool batts that should give me a R-23 insulation factor, however, what should I do between the exterior purlins? Foamboard would be the cheaper option, but should I be concerned with moisture build-up between the back of the exterior metal siding and the foam? Any tips would be greatly appreciated.

[glenn bradley]

For an little extra I stepped up to 2x6 walls on my 30 x 40 shop building. The additional cost (lumber and insulation [R19 versus R13]) paid for itself in a few months. I have been enjoying the benefits of that decision ever since. Spray foam insulation is cost prohibitive out here. Apparently it is the low cost option in other parts of the country so I cannot really help with a material selection. Plenty of others on here who can chime in though. Enjoy.

[Brian Tymchak]

Jim Becker recently built his new shop which I believe is of similar construction as yours. He lives in eastern PA so he has similar seasonal weather as we do here in Ohio. He did an excellent job of documenting the build and all his design and construction decisions in this thread.

[Jim Becker]

I'm planning to insulate and then put purlins on the inside to attach some sort of panel-metal siding, T1-11, plywood...not sure yet. For between the purlins, I'm planning to put up Rockwool batts that should give me a R-23 insulation factor, however, what should I do between the exterior purlins? Foamboard would be the cheaper option, but should I be concerned with moisture build-up between the back of the exterior metal siding and the foam? Any tips would be greatly appreciated.

You should watch the current RR Buildings "HQ v2.0" videos...Kyle just installed Comfort Board between the exterior girts (purlins are on the roof) which not only filled up the space, it also tucked behind the posts to deal with thermal break. The 1.5" Comfort Board fits right into the space beautifully when cut accurately. (Hopefully your post frame building used a level on the girts. ) Had I known about this method last winter, I would have done the Rockwool for the walls on my own new post frame shop building instead of the spray foam. (I would have still done spray foam up top since I intended to keep it open)

BTW, when you get to laying in the R23 Rockwool, if you have any loosness at all, a few lengths of string or fishing line will keep it up until you put in your interior girts.

[Steve Goetz]

Jim, I'm currently watch RR's build also! I have considered this as an option, but not sure of its cost. I love his meticulous...almost OCD...ways! Thanks for the insight and I'll be sure to check out the thread on your build that Brian mentioned!

[Steve Goetz]

Glenn, I should have specified, I am using the full 2x6 walls on my build (coming flush with the inside 6" posts. Thanks

[Jim Becker]

Jim, I'm currently watch RR's build also! I have considered this as an option, but not sure of its cost. I love his meticulous...almost OCD...ways! Thanks for the insight and I'll be sure to check out the thread on your build that Brian mentioned!

The Comfort Board does add some cost, but it's one of the most elegant ways I've seen to do this. You certainly could stuff in some regular inch and a half Rockwool if you can find it, but the board is stiffer and stays put as you must have seen in Kyle's videos. Certainteed has a similar product as does the "pink brand". If you opt for the software stuff, a little spray adhesive might be necessary. One thing to note from Kyle's videos is how well you can stuff the corners which are the most difficult place to deal with in any building including a post frame structure because there's always space between the outer covering and the corner of the posts due to the girts.

[Steve Goetz]

The Comfort Board does add some cost, but it's one of the most elegant ways I've seen to do this. You certainly could stuff in some regular inch and a half Rockwool if you can find it, but the board is stiffer and stays put as you must have seen in Kyle's videos. Certainteed has a similar product as does the "pink brand". If you opt for the software stuff, a little spray adhesive might be necessary. One thing to note from Kyle's videos is how well you can stuff the corners which are the most difficult place to deal with in any building including a post frame structure because there's always space between the outer covering and the corner of the posts due to the girts.

Agree for sure. I'll have to look into this and see just how much it costs around here. Any insight on a vapor barrier? Unfortunately, unlike your build, they did not put up a vapor barrier on the outside purlins before putting up the metal. I'm going to be conditioning mine...with a mini-split like you have done and want to have a vapor barrier of some sorts, but there is so much conflicting information out there, I'm confused to say the least!

[glenn bradley]

Glenn, I should have specified, I am using the full 2x6 walls on my build (coming flush with the inside 6" posts. Thanks

Ah, got it. I am sure some of our members who live where pole barns are the norm (wish they were here) will be more help than I am . . . being SoCal weather-handicapped and all

[Jim Becker]

Agree for sure. I'll have to look into this and see just how much it costs around here. Any insight on a vapor barrier? Unfortunately, unlike your build, they did not put up a vapor barrier on the outside purlins before putting up the metal. I'm going to be conditioning mine...with a mini-split like you have done and want to have a vapor barrier of some sorts, but there is so much conflicting information out there, I'm confused to say the least!

If they did not do wrap before the steel, then it's worth considering a "flash" coat of closed cell spray foam to seal all the nooks and crannies relative to air infiltration which also brings the benefit of a vapor barrier. But if you only want vapor barrier, given you are in Ohio, that goes on the inside for a traditional insulation design in these latitudes so you can get your R-23 in the bays and then put a poly vapor barrier over it before installing your interior girts to support the inside wall coverings. That gives you clear horizontal channels inside the vapor barrier to run your wiring, etc. before cladding the walls with whatever you choose. If you are putting actual stud walls between your posts...wiring will be more difficult as you have to drill through the posts or bring everything down from above. Drilling posts is not recommended in a post frame building if it can be avoided other than for installing bolts, etc., for structural purposes. Stud walls between posts also raises the material costs in a meaningful way which takes away from the economics of doing post frame to begin with. It also brings thermal bridging that filling the entire bay between posts with Rockwool takes away. Nothing wrong with it, of course, but $$.

[Bill Dufour]

(lumber and insulation [R19 versus R13]) paid for itself in a few months.
Why does California still allow r13 and r19 instead of r15 and r21? I do not think there is much ,if any, extra cost.
Bill D