hybrid insulation for pole building house

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  #1  
Old 11-01-14, 07:28 PM
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Cool hybrid insulation for pole building house

Hi all,
I have recently built a 48x96x16 pole building. This will be split down the middle making it 48x48 house and 48x48 garage. Both will have two levels, but not full, just more or less lofts.
My question now is about insulating the walls. There is nothing there, just the outer metal then the 2x4 wall ties. I was thinking of 2" rigid board foam against the 2x4's, sealed at all the joints, then framing 2x4's across the posts for my interior walls and using r13 that will be up against the rigid board (no air space), then the interior wall. That will be drywall only in the garage, then drywall and board/batten in the house part. So the only airspace would be between the metal and the rigid foam, about 1.5".
-or-
Use double bubble against the 2x4's, then frame and put the fiberglass batts against that. The only airspace would be between the double bubble and the metal (about 1.5", the width of the wall ties). Outer metal, 2x4 wall ties, the double bubble, then the fiberglass batts, then the interior wall.
-or-
Frame and install r13 fiberglass batts, then use the double bubble as a vapor barrier, then install the drywall ontop of that.

I can't use the fiberglass up against the metal, and I have a ton of r13 already, so that is the main reason I'm looking to add to what I already have instead of just buying new higher grade R. My batts are faced with paper, not unfaced. I have read back and forth that the facing is a vapor retarder. Retarder or barrier?

I'm in southeaster ohio, humid summers and pretty cold winters. Combined with metal siding, I have to make sure I get the right combination. I also live in the middle of a field with LOTS of wind. No protection/shade.

Thanks all
 
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  #2  
Old 11-10-14, 10:24 AM
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So no one has done this before, or am I in the wrong forum or something?
 
  #3  
Old 11-10-14, 11:53 AM
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Hi high toned,
I'll be honest, when you mentioned using double bubble I went to the next post. We can work out a best practices approach for you but IMO it will not include radiant barriers in Ohio.

In addition, your building is not a standard building therefore I would need some more details. Currently I don't have a complete picture of what you are proposing. I have a link that covers many aspects of building construction so I'll start there. I'll try to get back this evening to do a better review and see where we can go from there.

Bud
 
  #4  
Old 11-10-14, 04:56 PM
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You will need 50% or more of the total R-value in the foam to prevent condensation from forming in the fiberglass.

I would opt for two layers or more of 1" foam. That way you will be able to overlap the seams and further reduce the ability for air to flow between the sheets.

I don't think you want the paper face on the batts if you are using the rigid foam. Bud will better be able to inform you on that.
 
  #5  
Old 11-11-14, 06:01 AM
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I guess that link would be easier to read if I attach it .
http://www.buildingscience.com/docum...build-renovate

There,
Bud
 
  #6  
Old 11-13-14, 08:35 AM
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The reason I was thinking of the double bubble was for a radiant heat barrier. The metal is dark, and attracts a lot of heat. Enough to where in the summer sun it's too hot to hold your hand on.
I figured the double bubble would reflect a lot of that heat instead of letting it radiate inward into the house.
 
  #7  
Old 11-13-14, 09:17 AM
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The atmosphere has been so poisoned from fraudulent marketing of foil bubble products that hope for any positive research has long been abandoned. I have applications in my cold climate where a radiant barrier is a cost effective solution, but it cannot be discussed among the most informed energy professionals, they just don't want to hear it. The ceiling of a cold crawl space is one.

That then leaves me to advise based upon my own due diligence and from that I would conclude it is probably a toss up. Using that money and space for insulation is about equal to the improvement that the bubble wrap would produce.

Then comes the moisture issue. Plastic bubble wrap is another vapor barrier and in many cases no vapor barrier is much better than risking two and although you are hoping for a summer improvement you must consider the effects on winter condensation within the wall.

Unfortunately I cannot point you towards any fruitful research as most all has already concluded one should never use those words, bubble wrap. Yes I'm annoyed with them as there are only 3 major modes of heat transfer, conduction, convection, and radiation, and I don't think we should be ignoring the latter.

End of my rant. Just be sure you have considered the Vb and moisture issues and make your best choice.

Bud
 
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