Foam board over or between girts?

[Lucky-Ducky]

Does it matter if EPS is installed over the girts instead of between them?

The pole building has housewrap between the metal and girts/purlins.

Would the 1.5” air gap cause any problems?

 

[jack stand]

I actually did both.
But no, that gap won't matter and might result in a "tighter" building even with wrap.

 

[The Cobbler]

no issues as far as I know. infact a bit of breathing room may have benefits

 

[Lucky-Ducky]

I actually did both.
But no, that gap won't matter and might result in a "tighter" building even with wrap.

I have enough foam for 3 layers. I am debating between the girts and then stacking 2 layers or just doing 3 layers over the girts (staggered joints on all layers).

 

[jack stand]

Go for it!
It'll pay you back for the effort in energy costs and comfort.

 

[CraigStu]

I can't imagine fitting it between the girts. You know they are X inches apart +- an inch. I would bet you end up either cutting the foam or leaving a gap for at least half of them.

 

[Lucky-Ducky]

I can't imagine fitting it between the girts. You know they are X inches apart +- an inch. I would bet you end up either cutting the foam or leaving a gap for at least half of them.

I would cut the foam to fit between the girts and either tape/foam-fill the gaps

 

[cmandp]

Over the girts would help create a thermal break as well. No direct path from outside to inside.

 

[NUTTSGT]

I have enough foam for 3 layers. I am debating between the girts and then stacking 2 layers or just doing 3 layers over the girts (staggered joints on all layers).

If I had that much foam, (guessing you have 1.5" foam) I would put a layer between the girts before the metal goes up. The the the other 2 layers on the inside, alternating joints/seams.

I'd cut, or at least attempt to, with a table saw outside. If the girts are spaced appropriately, you should have to make no fence adjustments.

 

[jack stand]

I would cut the foam to fit between the girts and either tape/foam-fill the gaps

The foam guns are amazingly cheap on Amazon but you just as good at a local lumber yard or big box for the foam cans and cleaner.

 

[CraigStu]

I would cut the foam to fit between the girts and either tape/foam-fill the gaps

I understand, but how many hours do you want to spend doing that would be my concern. Vs quite a few replies here who feel that an airgap would actually be beneficial.

 

[PWC Repair]

Mine is all between the girts WITH an airgap to the metal. My ridge is vented and the small eaves have some venting as well. At some point I'm going back over the ceiling from the inside to cover the purlins up but haven't done it yet. I've been working out of my shop for about 8 years now and am CONVINCED the air gap helps A LOT in the hot weather. Pics and info are in my thread below.

 

[billconner]

I believe continuous insulation outside of the girts is worth it if you can afford it.

 

[wolfhawk73]

Over or both, not between. To loosely quote Joe Lstiburek, there's a reason we put a sweater on the outside of our body versus shoving wool between our ribs.