Encapsulated batt insulation = reversed vapor retarder?

[Michael Thomas]

Any experience/opinions of whether this type of insulation creates enough of a reversed vapor retarder to be a significant problem?

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[John Kogel]

I don't see that product here, but know it comes in a roll, handy to install.

I would be inclined to stick my hand in there and check for moisture. My handy moisture meter. :D

If the poly was punctured water vapor could get in with no way out. No punctures, no problemo.
I suppose the poly could be slashed if it is a concern or if moisture is found in there.

[Jerry Peck]

Looks like I see built-in elongated slot perforations along the edges, two rows of them.

I would think that should suffice to allow moisture to migrate out, given that it is sealed and moisture is restricted from migrating in.

i like the Handy Dandy Always With You Moisture Meter John referred to ... ;)

[Jay Urish]

I used some of this in my attic. It has micro perforations on each side. I put it in 5 years ago and now the outer plastic as biodegraded in the texas attic heat.

[Don Horn]

I installed some of this stuff 20 years ago. Do not know if still on the market. As I remember, the pink "plastic" envelope is NOT​ a vapor barrier. It is intended for the comfort of the installer only. Marketed to the do-it-yourself-er who was sensitive to the feel of fiberglass.

[kenny martin]

The name is Pink Plus by Owens Corning, with Mira-Flex fiberglass insulation, it is considered unfaced due to the perforations and can be googled for more info, here is a short explanation through Oikos website.. Miraflex Insulation - Oikos (http://oikos.com/esb/39/PinkPlus.html) we used it alot here and liked it due to the less itch application.

[H.G. Watson, Sr.]

Owens Corning, 'Pink Plus' - pink perforated plastic sleeves over miraflex (that may be what is pictued).
Johns Manville, 'Comfort Therm' - White perforated plastic sleeve.

I believe both made versions with or without one-side barrier vs. four sides perf'd (example J.M.'s "Sound Control" and R-25 products were perf'd on all four sides) depending on additional insulation retrofit, application side, vs. replacement or new construction.

IIRC there was a knock-off version at Menards and the former Builders Square in your market, recalling one more red than pink with standard yellow fiberglass batt inside, and recall "bag tubes" on continuous roll for DIY filling unfaced batt rolls.

perforated plastic is not a vapor barrier, was considered vapor perm-able, holes (openings) allow passage of vapor may still retain liquid (condensed, etc.) water.

plstic perforated sleeves still considered exposed by some jurisdictions and required cover esp. in storage, air hndled & mechnical environments. I don't recall either still offered in local stores for a while...haven't actually looked in some time for such though. A TIJ poster claimed OC hadn't produced since '-03 but I'm not so sure about that.

Here is a link to a 2007 discussion on TIJ...

Bagged/Plastic Wrapped Batt Questions - The Inspector's Journal Forums (http://inspectorsjournal.com/forum/topic.asp?TOPIC_ID=4319)

Here's a link to a 1997 J.M. news release:

Johns Manville Offers Complete System of Poly-Encapsulated ComfortTherm™ Fiber Glass Insulation (http://www.jm.com/insulation/news/414.htm)

Attached (attempt) pdf to product page on JM's comfort therm here is the link (discusses both PSK (Polypropylene-Scrim-Kraft) faced non-perforated (perm = 0.1) and PSK perforated versions (perm = 30+), as well as unfaced insulation) was for "the basement" version, There was an attic, interior wall, and exterior-above grade wall version IIRC, as well (at one time) The document is dated 2002: http://www.jm.com/insulation/building_insulation/products/bic447_basement_wall_insulation.pdf



HTH, Michael.

[tom harding jr]

Jay you had mentioned having noticed deteriorated moisture barrier on insulation from attic over heating problems, you may want to inspect the roof system for issues too.