Pole building wall insulation

[mrbreeze71]

Hi Group-

My barn is a 36' X 50' x 12' pole type building with metal siding and roof. Side wall posts 8' centers.

The entire building is covered with Kimberley Clark "Block-It" housewrap.

The use of the building is mainly shop, not every day. Not looking for man-cave, or to heat it to 80 degrees. Just enough to take the edge off and hold a little heat.

I don't really want to stud the walls out flush between the post.

If I were going to use foam board on the walls.... am I better off to go with 1 1/2" foam board between the purlins or should I just go with 2" and go OVER the purlins? I'm not understanding the air gap issue well enough, or the thermal connection between the purlins and the outside (though as noted there is Block-It outside of the purlins.

Not sure yet what I will finish with, but am leaning toward an interior grade metal.

Thank you!

 

[jack stand]

I'd start with the 1 1/2" in between the purlins. If you later decide that you want more, add 2"to the inside.
I'd suggest buying a foam gun to fill the edges and any gaps around the edges of the foam and the purlins. The (expanding) foam "gun" takes a large foam can/cartridge and you can only use what you need unlike the can foam that you have to use the whole can or it will harden up. The gun has a rigid metal tube for positive placement of the foam vs the stupid "straw" that you get with the can.

 

[EngineerNate]

The non-stick coated guns are worth the upcharge.

 

[mrbreeze71]

I'd start with the 1 1/2" in between the purlins. If you later decide that you want more, add 2"to the inside.
I'd suggest buying a foam gun to fill the edges and any gaps around the edges of the foam and the purlins. The (expanding) foam "gun" takes a large foam can/cartridge and you can only use what you need unlike the can foam that you have to use the whole can or it will harden up. The gun has a rigid metal tube for positive placement of the foam vs the stupid "straw" that you get with the can.

Thanks for the tips. Maybe you can clear up a little confusion... I've seen some say that you should go "over" the purlins to leave an air space between the foam board and the housewrap/steel. That of course would be a 1.5" air space. I don't know what the theory is there. Some say a thermal break? Any thoughts? It seems like insulation questions are a hot topic here and the answers are all over the place.

 

[billconner]

the answers are all over the place.

Yup.

I don't see value in the air space and do like filling behind posts. Same a spray foam.

Later you could consider fibreglass - the 8' wide Batts with vinyl.

 

[purediesel]

I see you're in MI so our weather isn't too different here in Oh. I did 1.5" XPS to fill the void between the girts and used the spray foam cans to seal the edges and make it air tight. Get the pro gun, worth every penny. Just the foamboard works great, but I also have an R44 insulated ceiling.. I am in the process of installing an R19 unfaced batt over the foam board to complete the insulation for the shop area. This will give me roughly an R24 to R26 wall cavity at a reasonable cost. No matter what you decide, keep in mind the need for your vapor barrier. If you only do the 1.5" in between the girts you will still need a vapor barrier on the warm side of the wall cavity. Now if you do a full 2" or more foamboard you wont need the vapor barrier, some things to research and think about.

 

[lazyriverrat]

I insulated my building similar to the way you have described. Block it house wrap, then 1 1/2 eps between the perlins to fill the void. Then 2" XPS over the perlins, bought the spray foam gun and sealed all the seams. Then I finished filling the wall with unfaced R13 batts.
I am happy with how it turned out and how little it takes to heat my shed. Spray foam would have been a lot easier but I saved enough to pay for my lights +plus. There is no denying it was a boat load of time and labor but it kept me out of the house.

 

[purediesel]

I insulated my building similar to the way you have described. Block it house wrap, then 1 1/2 eps between the perlins to fill the void. Then 2" XPS over the perlins, bought the spray foam gun and sealed all the seams. Then I finished filling the wall with unfaced R13 batts.
I am happy with how it turned out and how little it takes to heat my shed. Spray foam would have been a lot easier but I saved enough to pay for my lights +plus. There is no denying it was a boat load of time and labor but it kept me out of the house.

This is the exact reason I chose the route I took. I was able the insulate with the 1.5" xps and an R19 batt, frame the walls and install electrical for thousands cheaper than my cheapest spray foam quote. At the end of the day mine is just a shop/barn, not my main living so the ROI didn't make sense.

 

[mrbreeze71]

I see you're in MI so our weather isn't too different here in Oh. I did 1.5" XPS to fill the void between the girts and used the spray foam cans to seal the edges and make it air tight. Get the pro gun, worth every penny. Just the foamboard works great, but I also have an R44 insulated ceiling.. I am in the process of installing an R19 unfaced batt over the foam board to complete the insulation for the shop area. This will give me roughly an R24 to R26 wall cavity at a reasonable cost. No matter what you decide, keep in mind the need for your vapor barrier. If you only do the 1.5" in between the girts you will still need a vapor barrier on the warm side of the wall cavity. Now if you do a full 2" or more foamboard you wont need the vapor barrier, some things to research and think about.

Did you finish off with OSB, metal or drywall over the batts, or just leave the batts exposed?

 

[Montyx5]

On my pole building with 10' centers, I also wrapped exterior, hung 10' wide one piece fiberglass blankets, covered ceiling and wall cavities with heavy plastic vapor barrier tapping the seams, then ran horizontal girts on walls for the wall covering. The 1.5 spacing of the interior girts gave me place to run my electric and air lines. I then covered the walls and ceiling followed by blow in insulation for the truss area. While the insulation blankets were some what pricey, the insulation, vapor barrier and girts went up with 2 friend and a rented platform lift in 8 hours. I have done it many other ways helping friends and it just seemed to be laborious with a lot of attention required to the details to get a good thermal break. The fiberglass blankets filled the cavity tightly between post and girts with a slight bulge. Its not just about insulation, half the battle is air movement. Tape your exterior wrap and vapor barrier seems and any punctures special tape designed for that purpose. The walls can be covered with OSB, metal or drywall or a combination of them.