dcg9381
Well-known member
Inspired by reading another "insulation" thread, I wanted to share a word of warning on one design using spray foam. I am (and have been) for the last decade a spray foam fan-boy, as the resulting heating/cooling costs on the structures (3 total so far) that I've done with spray foam have been outstanding.
And given that construction techniques with foam seem to vary by climate, perhaps due to how much humidity control you need. I'm in the south and our AC runs 95% of the time, so we don't have much humidity to deal with. I spray directly to roof deck. There is quite a bit of "disagreement" especially within garage / barndo construction on if you spray to roof deck or steel panel. My vote is "yes".
This structure is up north, it's a 6-car garage with an apartment over-head. It's construction (framing) and workmanship are some of the best I've seen and a lot of money was spent adding R value. The insulation design is closed cell foam, but the design leaves an air barrier between the foam and the roof deck.
I was doing network wiring in this structure and noticed two huge cracks in the foam insulation. On on each end of the structure.. This is the "smaller" of the two insulation issues. You can see daylight (garage below) at the bottom, which definitely "unseals" the envelope. you can see roof deck.
Root cause of this is spraying closed cell foam not to the roof deck, but to a layer of what is essentially cardboard. Spray foam is only as good as what you attach it to...
And given that construction techniques with foam seem to vary by climate, perhaps due to how much humidity control you need. I'm in the south and our AC runs 95% of the time, so we don't have much humidity to deal with. I spray directly to roof deck. There is quite a bit of "disagreement" especially within garage / barndo construction on if you spray to roof deck or steel panel. My vote is "yes".
This structure is up north, it's a 6-car garage with an apartment over-head. It's construction (framing) and workmanship are some of the best I've seen and a lot of money was spent adding R value. The insulation design is closed cell foam, but the design leaves an air barrier between the foam and the roof deck.
I was doing network wiring in this structure and noticed two huge cracks in the foam insulation. On on each end of the structure.. This is the "smaller" of the two insulation issues. You can see daylight (garage below) at the bottom, which definitely "unseals" the envelope. you can see roof deck.
Root cause of this is spraying closed cell foam not to the roof deck, but to a layer of what is essentially cardboard. Spray foam is only as good as what you attach it to...
