barndo wall insulation

[latemr2]

Hey all, long time lurker here. Always get great info here, so thought I would pose a question.
I have a barndo I'm in the middle of building. Since getting the radiant floor running, it's having a tough time keeping temperature. My exterior walls are 2x6 horizontal steel girts with zipboard, Keene Easy-Fur strips, and pine siding. I had two inches of closed cell sprayed inside the entire structure. My neighbor had a LOT of batt fiberglass sitting in his garage that I also put in. (see attached illustrations)
Since the steel girts are one heck of a thermal bridge, I have been considering installing 1/2" EPS sheets between the girts and the drywall. My concern is moisture and/or if this is a bad idea. I'm in the middle of Missouri and get all 4 seasons weather, sometimes within the same week. Any input would be great!



add a sheet of eps before drywall to reduce thermal bridging?

 

[kj_mustang]

With the 2" closed cell foam, you have created an air and water vapor barrier at that point. You would need to maintain moisture levels to the inside of it through allowing water vapor to pass to the interior and proper exterior venting or ac/dehumidifier control of the interior. Looks of factors can contribute to the heating issue, adequate radiant heat loops and supply BTUs, air leakage at doors/windows, etc.

 

[billconner]

I concur with kj - you don't want a separate interior side vapor barrier. I don't know if strips of rigid foam would stop the temperature difference of the steel studs from telegraphing through the drywall.

Convection and radiation still are the greater means of heat loss over conduction.

 

[Allan00]

The challenge you are going to have is the fiberglass insulation contains tiny air pockets by design and these air pockets hold moisture (as any air does). What you don't want to do is have a vapor barrier on both sides of this insulation since any increase in moisture will have no where to dry to. This means closed-cell spray foam is a no-go.

A separate but related concern I have is the fiberglass insulation directly against the steel girts. If I'm seeing the right, there is a large potential for condensation at this point. The closed cell spray foam should have encapsulated the steel girts.

 

[coldh2o]

No comments on the wall structure, other than agreeing you do not want to add a vapour barrier (EPS) on the inside if the fibreglass.

WRT the question of heating efficiency, what is your ceiling insulation situation? You lose a lot more heat out the top than the sides.

 

[loganb]

More insulation in walls will be better, but agree with prior comments on not to do another vapor barrier


Also agree with above...what is ceiling? Is there a ceiling or this open to roof? If no ceiling is in yet and it's planned...get moving there. The heat loss vertically is huge. If its goingto stay open, look at some big fans to get air movement going so you can help redistribute your hot air from the ceiling area back down where you can feel it.

 

[dcg9381]

I'm with others, no "double" moisture barrier. You've already got one and you don't want to create a problem. You have a really well insulated structure, with Zip (is it zip-R?) we're talking about very minor "Matt Risinger" level improvements but at the risk of a double moisture barrier. Wanna go nuts, I'd use a "thermal break" tape on the gurts before drywall.

This is a structure that we completed last year, it shows the insulation design of the roof, but it's very similar to yours. Additional bats were added in the floor.