attic air sealing and vapor barrier

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  #1  
Old 09-28-16, 06:44 AM
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attic air sealing and vapor barrier

Hi,
I'm currently working on an old attic that looks like it's been properly air sealed and is filled with loose blown in insulation, but after a short inspection, i noticed there is no vapor barrier. Any recommendations on whether I should install a vapor barrier? I was thinking of moving the insulation and putting on an polyethylene vapor barrier, then putting the insulation back.

Thanks
 
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  #2  
Old 09-28-16, 06:53 AM
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Instead of installing a plastic vapor barrier I'd coat the ceiling with a vapor retarding primer sealer. Easier and possibly more effective since there won't be any voids if you cut the plastic for the joists cavities and a LOT easier than going up/down over the joists.
 
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Old 09-28-16, 12:03 PM
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I didn't know that was a possibility. I'll look it up. Thanks!
 
  #4  
Old 09-28-16, 04:26 PM
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With a location in your profile someone may well know if you even need a vapor barrier.
Just as important is to have proper amount of insulation and roof venting.
https://www.energystar.gov/index.cfm...sulation_table
Just a wild guess, but mine would be that at least 99% of the homes built in the last 50 plus years have no vapor barrier and there just fine.
 
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