Vapor Barrier use in western WV


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Old 04-07-14, 06:24 AM
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Vapor Barrier use in western WV

Hello all -
This has been the most confusing topic in home improvement, in my opinion. I have a 1962 brick ranch-style house. I found out when I first bought the house that back in the 60's they thought brick was a good insulator. They were WRONG! I decided to tear down the drywall of my exterior walls and put in Roxul mineral wool insulation. While I had the walls down, I decided to also update the electrical.

When it came time for me to re-drywall, I noticed a lot of people recommended vapor barrier. Problem is... a lot of people also recommended against it. I already bought the plastic rolls so I decided to do three bedrooms worth of drywall and put up 6-mil plastic as a vapor barrier. The guy I hired came in and drywalled those bedrooms without a peep.

Im now to the living room and the insulation is up. I get a different guy in here and he tells me that they stopped doing vapor barrier in the 80's here in WV because it wasn't recommended because of our moderate climates. We have cold winters but we also have hot summers.

What do I do? Do I put up vapor barrier? Should I have not put it up in the three bedrooms? Should I rip down the new drywall and take OUT the vapor barrier I put up? Any help would be most appreciated!!!
 
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Old 04-07-14, 07:19 AM
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Welcome to the forums. Cold winters and hot summers would be a good reason to have the vapor barrier. Roxul is both flame retardant and moisture resistant, thereby making it one of the best insulation materials available, IMO. I don't think you have done any harm in applying the barrier in the rooms. Roxul does indicate a vapor barrier is to be applied on the warm side of the house, or on the interior stud faces of exterior walls.
 
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Old 04-07-14, 08:40 AM
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Hi exhausted and welcome to the forum, and don't feel alone.

I'll add to Chandler's comment, "a vapor barrier is to be applied on the warm side of the house", but the question in your climate is, which side is that? Inside in the winter and outside in the summer, if you use air conditioning. Since installing one in the middle is really not practical what does everyone who lives in a mixed climate do. Simple, air seal and omit the vapor barrier.

Air flow transports far more moisture than diffusion so if you have eliminated 99% of the leakage then you will have sufficiently limited the potential for a moisture problem. For the existing areas where you have already installed the plastic, new construction with attention to sealing penetrations will have resolved most of the concerns. Drywall and that plastic, if sealed, form a good air barrier.

In the energy trade there is a phrase "the house works as a system", and all of the other details add up to give you a final answer and those details are the reason there are so many variations in the advice you can run into. What works for one home in one region may not be good advice for another.

I'll tack on a link on vapor barriers that may help. Bottom line is, the completed work is just fine as Chandler stated and if air sealed, no vb is necessary to the new work. A big "unless" is whether code requires it. Codes are farther behind than we would like.
Vapor Barriers or Vapor Diffusion Retarders | Department of Energy

Bud
 
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Old 04-07-14, 04:41 PM
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I might add, if you monitor and control indoor moisture generation then a good deal of the potential for a problem is eliminated. Do you have any idea what the RH is in the heating season?

Is the house on a crawl space or basement that is wet/damp? There are a variety of moisture contributing sources in a home and I'm sure if you just think about it you will be able to develop a list of those potential sources. The more moisture you generate....the more you have to deal with it.

You should also realize that an acceptable vapor diffusion retarder can be implemented utilizing various primer and finish paint coats. Some paints are going to be more impermeable than others.
 
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Old 04-08-14, 06:50 AM
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Many thanks!

Hey all -
Thank you for the replies! It has eased my mind a bit.

As far as air leakage, I was intending to spray foam my walls but the only contractor in my area that would do it was way too expensive and when I saw that I could buy Roxul pretty cheap (I work at Lowe's *wink*) I figured it would be the easiest to install myself. I do have a basement but I have 2 dehums running during the summer and do intend on finishing it up in the next year - waterproofing and the like. The basement windows are the old fashioned aluminum crank-style and they were leaking air so bad that weeds were growing thru and into the space of the house. I took 2 in rigid foam board, screwed it into the frame of the windows and caulked around that to seal the window space completely. Don't need the windows right now so why accept all that air leakage into the house?
We have a newer A/C unit - just purchased last year - so the house shouldn't have too much humidity infiltrating. The brown fiber-like board that is used for the exterior of the house just before the brick is put up I believe is supposed to be a vapor retardant of sorts. It had several holes in it so I patched it up with caulking before insulating and sealing the space. I think I will continue to vapor barrier the house just because I haven't seen any signs in the last year of doing so that it is counterproductive to what Im doing.
Again, I really appreciate the input and look forward to future topics and maybe even supplying my own help on the forums!
 
 

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