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I live in Arkansas with mild winters, and really, really humid summers. I have 1/2″ ply sheathing on 2×6 walls, wrapped with Tyvek, and covered with vinyl. I currently plan to use wet-sprayed cellulose in the walls (higher effective R-value, quieter, actually cheaper). Should I use a vapor barrier (VB) on the walls, a vapor diffusion retarder (VDR), or just drywall with good paint (oil-based?). (In a nutshell, please — I’ve read every post on this subject I could find, and I’m still confused about this!)
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crusty... since i've been hanging out in BT.. i've rethought some of my strategies..
in your situation , with your climate... your 2x6, tyvek,& vinyl siding..
given that you are going to use sprayed cellulose..
i'd choose the VDR...
the cellulose can store excess moisture during high Rel.Hum. times... and then give it up to the exterior thru your Tyvek and the joints in the vinyl...
if you had fiberglass batts.... i would absolutely use the VAPOR BARRIER...
as you have already figured out.. the total combination of all the components is important... how they all work together...
.genel's book talks about VDR.. and lstiburek has three books ... one for cold climate (me).... one for mid-climates (you).. and one for the south....lots of good discussion there too...
how many Degree Days where you live ? average low temp. in January ?
hmmm....
*MikeThe very reason you suggest an interior vapor barrier in this situation is the exact same reason why I would not use one. The cellulose will "manage" the moisture levels and dry to inside and outside as the RH permits. Other wise the great performance features of the cell are not being taken advantage of. Funny, eh!
*tedd... we're on the same page but you're not reading what i wrote......i didn't say this ...((you suggest an interior vapor barrier in this situation is the exact same reason why I would not use one. ))...i told rusty that since he was using cellulose, i would NOT use a vapor barrier...(i would use a VDR..).. i then went on to say that if he had used fiberglass.. i would use a Vapor Barrier..now.. did you mistate your position .. or are we in agreement ?
*Sorry Mike, I misread your post. Guess I have some defensivenss on this topic after so many people have been bruised by it. Forgive me, we do agree.
*tedd... group hug... ... you get one raseanna roesanna danna......(never mind )...
*Wonder where the antagonists are on this issue ?
*I agree a VDR is probably what I need; no one puts poly on the inside around here -- there must be a reason. But what exactly qualifies as a VDR (for use on an inside wall)? Gene seems to think that kraft facing (NOT stapled on the sides of the studs) is quite effective, but I'm not using batts. What else is there? (Be specific, please).
*Go with the paint solution (advanced drywall approach - ADA - look it up).
*I disagree!!!!there, we all feel better now that there's an arguement.Just kidding about the disagreement thing.ok, I'll shut up
*I feel better now, even if the disagreement was only in the first line of your post.
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I live in Arkansas with mild winters, and really, really humid summers. I have 1/2" ply sheathing on 2x6 walls, wrapped with Tyvek, and covered with vinyl. I currently plan to use wet-sprayed cellulose in the walls (higher effective R-value, quieter, actually cheaper). Should I use a vapor barrier (VB) on the walls, a vapor diffusion retarder (VDR), or just drywall with good paint (oil-based?). (In a nutshell, please -- I've read every post on this subject I could find, and I'm still confused about this!)