# Vapor barrier in garage (room over) ceiling



## joecaption (Nov 30, 2011)

Always goes toward the conditioned side. (A/C Heat)


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## Gary in WA (Mar 11, 2009)

In a heating climate, to the inside. In a cooling climate, toward the outside. 

Because you are facing a cold garage space with outside air, I would use foil-faced foamboard on the joist bottoms. This will keep the dew point from condensing in the cavity and give an air break if you seal the joints. It also uncouples the joists from the outside temperature; fig. #7: http://www.buildingscience.com/documents/insights/bsi-009-new-light-in-crawlspaces/
Cover with 5/8" type X drywall, mud/tape the seams. 

Gary


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## joecaption (Nov 30, 2011)

http://insulation.owenscorning.com/uploadedFiles/HomeOwnersGuideToInsulating.pdf
I've never heard of install it according to it being a heating or cooling area.


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## Windows on Wash (Aug 30, 2011)

joecaption said:


> http://insulation.owenscorning.com/uploadedFiles/HomeOwnersGuideToInsulating.pdf
> I've never heard of install it according to it being a heating or cooling area.


He is referring to the climate zone not HVAC.

Heating climate (i.e. an area of the country where they have more heating degree days) vs. cooling climate.


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## Gary in WA (Mar 11, 2009)

On the *warm side*. When I see a picture of a crawlspace with paper facing down, first where they live……it may be correct.








Gary


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## wwsteel7 (Apr 14, 2009)

One solution is to provide a heat duct or two-depending on the size of the garage/living space, directed underneath the future living space.

Then, after the heat ducts are installed below the floor joists of the future living space, frame a 2 x 6 drop-ceiling in the garage below the floor joists of the future living space. 

Then, install your 6-mil poly on the bottom of the floor joists of the future living space, being careful to get underneath the ducts, so that the poly is under all ducts, stapled periodically to the floor joists but not too tight- you want the poly to be a little loose so as to allow air flow underneath the joists. Use tuck-tape on all joint seams and the perimeter.

Finally, install your insulation into the drop ceiling. R-28 insulation is the minimum I recommend.


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