Anybody used Certainteed \"MemBrain\" vapor retarder
??????? It's too late to ask now(since I've already bought and installed a lot of it)....but more or less to make others aware of the product. I've been very concerned about any moisture being caught behind the drywall but in front of a 6 mil poly barrier since the poly does not "breath"...have read too many cases of mold build up and rotting walls, etc. In PA we not only have the less humid but very cold winters...but also the VERY humid summers. This stuff(recently patented in USA) has been used in Europe for several years.....made of a material that changes it's permiability with humidity....closes up in dry conditions to block moisture(mainly in our heating season) but opens up slightly in humid conditions to allow moisture to pass through. I've installed in all exterior walls...will not install in ceiling as it seems the current theory is to not have any barrier in the ceiling as long as adequate ventilation is there..............any thoughts? [img]/forums/images/icons/crazy.gif[/img]
Re: Anybody used Certainteed \"MemBrain\" vapor retarder
Muncy,
Here are my thoughts. Keep in mind, this is only my thinking, and it may not apply to you at all. I used 6 mil plastic as my vapor barrier. I did so because it's on the outside of my construction, covering my sheathing. I'm going to spray insulation on the inside walls behind my drywall. Now, I don't know, but it seems to me that any moisture from the inside is going to have to penetrate all of that sprayed foam, not to mention the drywall barrier, and I'm not so sure that it can do that. I don't want any moisture penetrating from the outside and the plastic should keep that from happening, correct? So why do you need a breathable material for a vapor barrier? It's kind of like gore-tex to me. The most expensive rain coat I have is gore tex and that sucker leaks like a sieve. It does opposite of what it's supposed to do which is keep the outside moisture out and let inside moisture escape. Anyway, this is my 'thinking' which may be crazy thinking, but I put plastic up for less than half the cost of house wrap. I'm in a part of Texas where humidity isn't usually an issue, but I am going to use evaporative cooling for air conditioning inside my home, so I will be creating humidity there.
Re: Anybody used Certainteed \"MemBrain\" vapor retarder
I don't think this barrier is meant for the spary in foam insulation...that would be a vapor barrier in itself, yes? And in your climate you need the barrier on the outside of the home and even if moisture does condense there you have a drain field...here the moisture would condense on the exterior of the inside wall...and no drain field, this would encourage mold, rot, etc. This stuff allows the moisture to pass through ..migrating to the outside...at least I hope it does! [img]/forums/images/icons/confused.gif[/img]
Re: Anybody used Certainteed \"MemBrain\" vapor retarder
It's always been my understanding that the reason for housewrap over plastic is that the housewrap will allow moisture to flow out. Once it is beyond the housewrap and away from the wood, it can run down and out of the wall. With plastic, moisture can't pass through and stays inside the wall, soaking into the sheathing. Housewrap is not intended to stop water from coming in from the outside. That is siding's job. It will make a second line of defense in the event the siding leaks, though.
I haven't seen the "mem-brane" stuff yet. Is it an interior or exterior treatment?
Re: Anybody used Certainteed \"MemBrain\" vapor retarder
this is an interior material used in conjunction with mainly fiberglass...but I guess it would be suitable to any insulation that needs a vapor retarder. In our climate conditions you would have the vapor retarder on the heated side of the insulation(interior) behind the finished interior wall(drywall, etc) and then the insulation, then the sheathing, housewrap and finally the extereior wall(siding, etc). In warmer climates the vapor retarder would be on the opposite side of the insulation....and as I understand it, way down south where it's humid most of the time they don't install the vapor retarder at all?? This stuff is thinner than 6mil poly but it's very tough stuff, had to remove a staple with a screwdriver and no damage to the material at all.
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