Not the first polyiso insulation thread…

[rcthorpe]

Looking at insulating the walls of a standard 4”X6” pole constructed barn with 4” polyiso panels. Thinking about furring out the 2”X4”girts between the 4X6’s with vertical 2”X2”, adding 4” polyiso panels over the furring strips, and then finishing over the flush face of the 4X6’s with 7/16 OSB. Main concern is the gap I am creating between the exterior steel and the insulation panel. Thoughts?

 

[PWC Repair]

Been in mine about 6 years with an air gap......check out my build thread below. The air gap works out great to keep heat out in the summer.

 

[Firebrick43]

Looking at insulating the walls of a standard 4”X6” pole constructed barn with 4” polyiso panels. Thinking about furring out the 2”X4”girts between the 4X6’s with vertical 2”X2”, adding 4” polyiso panels over the furring strips, and then finishing over the flush face of the 4X6’s with 7/16 OSB. Main concern is the gap I am creating between the exterior steel and the insulation panel. Thoughts?

I wouldn't create such a gap because it gives a nice home to rodents.

It would be just fine against the face of the outside girts. But also, the question is why?

I advocate putting 1.5 xps or polyiso in-between the girts to add insulation, and could see adding another 0.5" layer over the face to seal everything off. Once you do that you have done a superb job weather sealing and moved the dew point into the foam(and added R7 or so to the assembly), use 6" fiberglass for the rest of the insulation. Its much cheaper per R value and the foam to the outside eliminated the huge negatives that fiberglass has on forming convection currents at high temp differentials

Some thinking where with spray foam they do flash and batt.

 

[rcthorpe]

I wouldn't create such a gap because it gives a nice home to rodents.

It would be just fine against the face of the outside girts. But also, the question is why?

I advocate putting 1.5 xps or polyiso in-between the girts to add insulation, and could see adding another 0.5" layer over the face to seal everything off. Once you do that you have done a superb job weather sealing and moved the dew point into the foam(and added R7 or so to the assembly), use 6" fiberglass for the rest of the insulation. Its much cheaper per R value and the foam to the outside eliminated the huge negatives that fiberglass has on forming convection currents at high temp differentials

Some thinking where with spray foam they do flash and batt.

My thoughts are that I can get 4" insulation relatively cheap, and by furring the insulation out 1.5" it gets me flush with the outside of my 4X6's to finish with OSB (without having to frame in all of the 4X6 cavities, as well cutting and filling all of the girt cavities). I feels like this would save some time and $$$. Not mentioned, but will certainly add a base plate.

Totally understand the rodent issue...

Thinking that by spray foaming around the edges of the 4" insulation, it should seal things off and keep any moisture issues at bay?

 

[billconner]

Is the poly iso cost effective? Have to wonder how sips would compare, considering it included inner wall covering, sheathing, and foam, all installed at one time. I would think it might replace girts too. Posts, sips, and metal panels.

 

[rcthorpe]

Getting the 4" polyiso for ~$40/sheet

 

[Firebrick43]

Getting the 4" polyiso for ~$40/sheet

That is cheap. Is it reclaimed or new?

 

[rcthorpe]

That is cheap. Is it reclaimed or new?

2nds

 

[davo727]

Anyone ever cut polyiso into 3inch wide strips and put it between the steel purlins and steel roof and wall sheeting as a thermal break? Im thinking 1 inch thick polyiso.

Im going to insulate from the inside after the building is up. I helped a friend build his 40x60 years ago with the giant fiberglass insulation rolls and vowed to never ever deal with that type again.