Vapor Barrier in Attic

Old 02-10-04, 05:02 PM
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Vapor Barrier in Attic

I have a building that is currently not heated or insulated. It's open up above all the way to the rafters. Besides the walls - I plan on putting drywall on the "ceiling" overlays - then insulating the "attic". Currently the ceiling is covered with heavy plastic sheathing. Can I leave this up there and put the drywall over the top? The plastic would then be a vapor barrier for the loose fill insulation or unfaced fiberglass. Would this work ??? Am I on track with this ??
Old 02-10-04, 08:44 PM
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I am not certain of the exact situation but if you are saying you have plastic sheet covering the ceiling joists, which you plan to cover with drywall, that's fine.

If you have multiple ceilings that you plan to cover with one last layer of sheetrock, I am not sure I would agree to that.

Multiple layers of anything (plaster, lath, sheetrock) tend to be uneven. Drywall fasteners are intended to hold up one layer of sheetrock, and expecting the fasteners to hold up much else ( insulation is OK) is not a good idea.

If you insist on veneering an existing ceiling use drywall screw and plenty of them.

I have laid plastic sheet from the attic side, and it's a pain in the butt. For those who have the need of a vapor barrier for a ceiling, you might be best served by the proper ceiling paint before you lay plastic sheet in the 'troughs' formed by the ceiling joists.
Old 02-11-04, 03:40 PM
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SteveBauch -
I ceiling is currently open all the way to the roof rafters - except for the plastic sheathing that I have on the ceiling joists. There are many seams. I wanted to put loose fill up there - but then thought about what about a vapor barrier.....then thought - hey not leave the plastic up and put sheetrock over it.

I know that a proper vapor barrier is important when insulating - so I'm glad that I'm on the right track. This way I can go with either loose fill or 6" unfaced fiberglass. I'll have to price it out.

Thanks for your help.
Old 02-14-04, 01:06 PM
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Dry wall right over the V/B on the ceiling go for it let the poly film there. BUT BUT BUT If its cold out put the drywall up dont tape it at all now. Have the insulation there to go on top of it right away.After the insulation is in then tape it. Boy have been there a few times the weather changes on you and the V /B will sweat bad when you tape it and there is no insulation there . the dry wall wont come down on you .But later on you will see the ceiling has cups in it from rafter to rafter ED

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