garage insulation, FACINGS/BARRIER is put on one side or both side?

I am wondering when I use fiberglass R12 or R14 to insulate my garage ceiling and walls, the insulation does not come with facings, so I bought plastic vapor barrier separately , I saw this barrier has a FOLDING on one side in purpose (not like a sheet as paper without folding one side), I guessed I should wrap the insulation then put on walls and ceiling,After I read article that saying only put barrier on one side,also facings on home-side,BOTTOM of insulation no need the barrier, due to moisture moving from inside home to outside,AM I WRONG? when it comes to putting the plastic vapor barrier over the home-side (not wall-side) of insulation, using small piece as insulation size or whole huge sheet to cover ?? If I use two layers of plastic vapor barriers, it is possible to cause moisture get in between and hard to escape? thank you master! I need do the job done before winter coming, even right now.


when I put the plastic barrier on warmer side( the facings face/toward in-house's person) , cut it to insulation-size (in Ontario, Canada here size is 15 inches wide for 2x4 wood stud) or use big barrier sheet to cover the insulation materia area as big as possible.thx

5 Answers

  • ?
    Lv 7
    5 years ago

    Vapor barriers differ depending on where you live. Up here in New England they go to the conditioned side. You do not want to wrap that insulation nor have vapor barriers on both sides, it will trap moisture then start growing some very not nice stuff. The garage ceiling you want a higher r value if you can get it in there, the walls you are pretty much limited to your stud size.

  • Jim W
    Lv 7
    5 years ago

    The vapor barrier is designed to keep the higher humidity air from reaching into the insulation. When the wet air reaches a cooler surface it gets the surface wet and then you loose your insulating values. The vapor barrier should go on the side with the warmer air during the cold season. This will keep the insulation dry and keep you warmer.

  • XTX
    Lv 7
    5 years ago

    read more about this online as your question is not very clear ..... if you have a Lowe's or Home Depot Hardware Giant near your home it is good advice for you to visit the store and see some insulation displays and learn more about the use of plastic barriers and exactly how they are placed ......

  • 5 years ago

    if you put the barrio on the home side of the insulation, it will get ruined the first time it condensates. if that's any help. I wouldn't worry much about moisture going from inside the home to the outside. that's crazy.

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  • Irene
    Lv 6
    5 years ago

    Go to Home Depot and explain your problem. They will give you expert advice.

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