Vapor Barrier when finishing attic roof?

Old 01-04-01, 06:53 PM
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I'm finishing my attic and wondering if I need a vapor barrier between the sheetrock and insulation. I have a large attic, walk up stairs, 10 feet high at peak, soffit vents and gable vents near peak. I have the foam rafter vents stapled to the plywood roof (they ventilate the air from the soffits to the peak), and i have R19 insulation with kraft facing. I wonder if the kraft facing and sheetrock (taped and spackled) is enough of a vapor barrier to keep the indoor moisture from reaching the plywood roof. I live in Maryland and not having the sheetrock on there yet, I notice moisture condensing on the plywood (under the insulation) since i have snow on the roof now. I guess i should wait for spring to sheetrock, to allow the plywood to dry out first. Also I plan on framing out a duct at the peak to allow ventilation from the foam rafter vents to crossflow and exit out the gable vents. Any advice regarding vapor barrier or that ventilation duct? Thanks.
Old 01-04-01, 09:46 PM
some help
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The tighter the vapor barrier the better. You need to have lots of ventalation in the attic from side to side and end to end. use what ever will work for venting, ridge vent roof vents, and if need be a power vent to get cross venting between plywood roof and insolation.....You do not have to wait until spring for the plywood to dries out install a fan to the outside add heat and let it dry....and add the insolation and vapor barrier before it can get moisture in the insolation.. you can watch and see if the plasic should sweat on the back side. You may have some sweting on the inside of the plastic as you did before on the plywood untill the inside drys completley..
by the way you should install vaoper barrier on the side walls at the same time... Good Luck

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