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Started By
Message
Insulation opinions, blown in.
Posted on 9/5/23 at 2:26 pm
Posted on 9/5/23 at 2:26 pm
I've gotten 3 quotes for insulating the barndominium. two called for spraying exposed tin in attic with 2.5-3" closed cell and 3-4" open cell in walls, these quotes were for 17,500 and 19,850, the low quote called for 8" open cell against all tin surfaces in attic and filling the 2x6" exterior framing...so 5.25" on all exterior walls. This quote was 15,400.
building insulated size 50x56x15.5" walls, 4/12 roof with straight gable ends.
I thought I wanted the closed cell but at that difference I'm leaning to the open cell quote. How much humidity would open cell let in at those thicknesses. The wall construction is 2x6 with 3/8 osb and then 30# felt wrapped. I'm also considering the open cell because I always hear about these buildings not breathing enough. Am I off base here?
building insulated size 50x56x15.5" walls, 4/12 roof with straight gable ends.
I thought I wanted the closed cell but at that difference I'm leaning to the open cell quote. How much humidity would open cell let in at those thicknesses. The wall construction is 2x6 with 3/8 osb and then 30# felt wrapped. I'm also considering the open cell because I always hear about these buildings not breathing enough. Am I off base here?
3
Posted on 9/5/23 at 4:21 pm to Wraytex
Where are you located?
Posted on 9/5/23 at 4:23 pm to shoelessjoe
Central Tx, about 2miles SE of Buccees near Luling, so a bit lower humidity than the majority here see.
Posted on 9/5/23 at 4:30 pm to Wraytex
not a fan of spray foam on above grade applications but that is just me.
if there is any structural flex potential either from wind or freezing, do not use closed cell foam. it will detach from the substrate over time and lose the "tight" benefit from closed over open cell. Open cell is much more flexible and able to move with a structure.
I'd personally go dense packed blown cellulose. You'll get great performance and your infiltration numbers will be as good as it gets without needing venilation/makeup air. You do spray foam and you WILL need a more complex HVAC system with makeup/HRV/ERV functions to get air changes required for healthy interior spaces. If your HVAC system is not sized and equipped for a tight spray foam construction, you will get very poor interior air quality.
You also get better sound attenuation with cellulose over foam.
if there is any structural flex potential either from wind or freezing, do not use closed cell foam. it will detach from the substrate over time and lose the "tight" benefit from closed over open cell. Open cell is much more flexible and able to move with a structure.
I'd personally go dense packed blown cellulose. You'll get great performance and your infiltration numbers will be as good as it gets without needing venilation/makeup air. You do spray foam and you WILL need a more complex HVAC system with makeup/HRV/ERV functions to get air changes required for healthy interior spaces. If your HVAC system is not sized and equipped for a tight spray foam construction, you will get very poor interior air quality.
You also get better sound attenuation with cellulose over foam.
This post was edited on 9/5/23 at 4:32 pm
Posted on 9/5/23 at 4:36 pm to notsince98
How well does cellulose adhere to the backside of R panel?
....and thank you for the suggestion.
....and thank you for the suggestion.
This post was edited on 9/5/23 at 4:37 pm
Posted on 9/5/23 at 6:45 pm to Wraytex
Yeah, little different than South Louisiana. I went with blown insulation in attic and batts in the walls.
Posted on 9/6/23 at 8:39 am to Wraytex
quote:
How well does cellulose adhere to the backside of R panel?
....and thank you for the suggestion.
Dense packed cellulose is packed. It doesn't adhere.
Posted on 9/6/23 at 7:48 pm to Wraytex
I am no expert, but in my way of thinking, I would want closed cell everywhere but on the underside of a roof…where you need open cell in case of leakage. I may be way off, though!
Posted on 9/6/23 at 8:42 pm to Spankum
I know I want the roof underside sprayed and a cooler attic, as that's where the AC will be setting.
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